Participants, Title of Talks and Poster
Contributions
- Abraão Jessé Capistrano de
Souza (Fundação Universidade Federal do Tocantins (UFT),
Palmas, Brazil)
- Tittle of Talk (STARS2011): On the Geometrical Effect
of Dark Matter
Abraão Jessé Capistrano de Souza, Pedro Ivo Odon and
Luis A. Cabral
Abstract: We
study the effect of the extrinsic curvature on the rotation
curves within the context of brane-world, in a 5-d bulk with
constant curvature. The covariant equations of motion for the
brane-world are applied to determine the modified Newtonian
potential approximation and the velocity curve. Two cases are
examined: first, we consider a galaxy predominantly dominated
by a spherical mass distribution leading to a small correction
to the usual Newtonian potential. Secondly, we consider a
static disk galaxy which is composed only by the ordinary
visible matter. Using the Weyl static metric as a model, we
find that the velocity curve is given by the square root of a
small power of the distance to the galactic center,
representing the brane-world warp caused by the disk edge.
- Alain Blanchard
(Institut de Recherche en Astrophysiqué et Planetology (IRAP),
Toulouse, France)
- Tittle of Talk (STARS2011): The Cluster
Conundrum
Alain Blanchard
Abstract: The
abundance of clusters and its variation with redshift has been
proposed as a powerful cosmological test. Recent studies have
shown that it may be used to bring critical information on
modified theory of gravity. However, existing data on x-ray
clusters abundance have been analyzed by different teams and
lead to contradictory results. I will discuss our latest
analysis of this question and show that indeed the abundance of
x-ray clusters seems to be at odd with expectation within a
standard concordance model.Solutions to this problem will also
be proposed.
- Alain Ulacia Rey
(Instituto de Cibernética, Matemática y Física (ICIMAF), La Habana,
Cuba)
- Title of Talk (STARS2011): Contributions of Riemann
invariants to the Entropy of Extremal Black Holes
Alain Ulacia Rey
Abstract: We
use the entropy function formalism introduced by A. Sen to
obtain the entropy of AdS2 X Sd-2
extremal and static black holes(BH) in four and five
dimensions, with higher derivative terms of a general type.
Starting from a generalized Einstein-Maxwell action with
nonzero cosmological constant, we examine all possible scalar
invariants that can be formed from the complete set of Riemann
invariants (up to order 10 in derivatives). The resulting
entropies show the deviation from the well know
Bekenstein-Hawking area law S=A/(4G) for Einstein's gravity up
to second order derivatives.
- Title of Talk (SMFNS2011): Perturbed Bianchi-I
Space-time with Magnetic Sources
Alain Ulacia Rey
Abstract: In
this work we calculate the complete set of cinematic variables
for a perturbed Bianchi-I space-time. In this order, we used
these general results on the Raychaudihuri equation that
physically could shed light for several physical conditions of
collapse, on a perturbed background.
- Alejandro Cabo Montes de Oca
(Instituto de Cibernética, Matemática y Física (ICIMAF), La Habana,
Cuba)
- Title of Talk (STARS2011):
Dilaton Stabilization by Massive Fermions
Alejandro Cabo, Robert Brandenberger, Matts Roos and
Encieh Erfani
Abstract: The
Dilaton stabilization problem is investigated when the
effective potential for this field is generated by the
existence of a massive fermion. The previously evaluated two
loop correction for this quantity indicates that the Dilaton
field tends to be fixed at a high value close to the Planck
scale, in accord with the needs for predicting Einstein gravity
from string theory. Moreover, the mass of the Dilaton is
evaluated to be close to the Planck mass, which assures the
absence of Dilaton scalar signals in modern cosmological
observations. These properties arise when the fermion mass is
chosen to be either at a lower bound corresponding to the top
quark mass, or alternatively, at a very much higher value
assumed to be in the grand unification energy range. The
renormalization scale μ is chosen to be given by the Z
particle mass. We also consider the case when μ is a
dynamical parameter fixed by minimization of the effective
potential. The results rest on the basic assumption that the
higher three or more loop calculations do not drastically
affect the two loop potential. Higher loop sample calculations
are expected to be considered elsewhere in order to give full
ground to the conclusions.
- Alexandre Mesquita
(Universidade de Caxias do Sul (UCS), Caxias do Sul, Brazil)
- Title of Poster Contribution
(STARS2011) (proposal): The Role of Isovector Mesons
and Antikaon Condensates in Pulsars
Alexandre Mesquita, Moisés Razeira,
Francisco Fernández, César A. Zen Vasconcellos and Dimiter
Hadijimichef
Abstract: In
this contribution we study the effects in the structure of
pulsars of isovector mesons and antikaons degrees of freedom.
For this task we consider a phase transition of nuclear matter
to nuclear matter containing a condensate of antikaons using an
effective model with derivative couplings. In our formalism,
nucleons interact through the exchange of sigma, omega, rho,
and delta meson fields in the presence of a background of
electrons to accomplish electric charge neutrality and beta
equilibrium. The phase transition to the antikaons condensate
was implemented through the Gibbs conditions combined with the
mean-field approximation, giving rise to a mixed phase of
coexistence between nuclear matter and the condensed of
antikaons. Pulsar rotation, in our approach, is implemented
considering interior solutions for the dragging frequency. Our
results confirm that isovector mesons operate to restore the
isospin symmetry of nuclear matter and to reduce the value of
the effective mass of baryons, a result that is independent of
the depth of the optical potential for antikaons. Also, as
expected, it was found that increasing the depth of the optical
potential favors the increase of antikaons population.
Moreover, assuming neutrino-free matter, we observe a rapid
decrease of the electron chemical potential produced by the
gradual substitution of electrons by kaons to accomplish
electric charge neutrality. The effects of rotation in the
equation of state are synthesized in this contribution.
- Title of Poster Contribution (STARS2011) (proposal):
Glueball-Dilaton as an Alternative to Dark Matter in
Neutron Stars
Alexandre Mesquita, José Eduardo Costa, César A. Zen
Vasconcellos, Moisés Razeira, Francisco Fernández and Dimiter
Hadjimichef
Abstract: We
study cold nuclear matter based on a mean field description of
baryons bound by the exchange of scalar-isoscalar,
vector-isoscalar, scalar-isovector and vector-isovector meson
fields as well as the glueball field. For this task, we use an
extended version of the effective model with derivative
couplings with genuine many-body forces simulated by nonlinear
self-couplings involving meson-meson interaction terms and the
glueball fields. In our approach, the realization of the broken
scale invariance of quantum chromodynamics is achieved through
the introduction of the dilaton field. The effective model with
dilatons is then applied to the description of neutron
stars.
- Title of Poster Contribution
(SMFNS2011) (proposal): Relativistic URCA Process in
Neutron Star with Antikaons
Alexandre Mesquita,
Moises Razeira, Francisco Fernández, Cesar Z. Vasconcellos and
Dimiter Hadjimichef
Abstract: Under
the framework of a relativistic mean field description of
nuclear matter with baryons bound by the exchange of
scalar-isoscalar, vector-isoscalar, scalar-isovector and
vector-isovector meson fields as well as antikaons degrees of
freedom, we study the cooling process of neutron stars and
pulsars.
- Andres Escala
(Universidad de Chile, Santiago, Chile)
- Title of Talk (STARS2011): Gas induced Mergers of
Massive Black Holes
Andres Escala
Abstract: Using
high-resolution SPH numerical simulations, we investigate the
effects of gas on the inspiral and merger of a massive black
hole binary. This study is motivated by both observational and
theoretical work that indicate the presence of large amounts of
gas in the central regions of merging galaxies. I will focus on
the role of tidal (ellipsoidal) torques in the MBHs dynamics.
In particular, I will discuss under which disk models the
formation of a circumbinary gap wil l be prevented and the
tidal torques will efficiently extract angular momentum from
the MBH binary, and under which models a stable circumbinary
gap will be opened. The final coalescence of the black holes
leads to gravitational radiation emission that would be
detectable up to high redshift by LISA, and will provide
spectacular insights into the formation and co-evolution of
galaxies and central black holes.
- Anna Maria Freire
Endler (Centro Brasileiro de Pesquisas Físicas (CBPF), Rio
de Janeiro, Brazil)
- Title of Talk (STARS2011): About the Unimaginably
Small and the Incredibly Large
Anna Maria Freire
Endler
Abstract: We
are the first generation of human beings to glimpse the full
run of cosmic history, from the universe’s origin in the
Big Bang to the silent flight of galaxies through the
intergalactic space. We are the first to make the connection
between the inner space of elementary particles and the outer
space, about planets, stars and galaxies. We can say, we can
now better understand about the entire universe. The detailed
information on sub-nuclear phenomena helps very much to
understand the evolution of the Universe, formation of Stars
and Galaxies. This talk has the intention to show how it can be
enjoyable the inner space and outer space adventure and to see
how they are connected. In the inner space, the elementary
particles and the different fundamental forces in the nature
are described and the attempts for a great unification
mentioned. In the outer space, it is mentioned the evolution of
the universe with the creation of galaxies and stars with the
different kinds of their deaths, resulting the black holes,
neutron stars and white dwarfs.
- Aurora Pérez
Martínez (Instituto de Cibernética, Matemática y Física
(ICIMAF), La Habana, Cuba)
- Title of Talk (SMFNS2011):
Compact Stars and Magnetized Color Flavor Locked
State
Aurora Pérez Martínez, R. Gonzalez
and Daryel Manreza Paret
Abstract: The
stability of the color flavor locked phase in the presence of a
strong magnetic field is investigated within the
phenomenological MIT bag model, taking into account the
variation of the strange quark mass, the baryon density, the
magnetic field, as well as the bag and gap parameters. It is
found that the minimum value of the energy per baryon in a
color flavor locked state at vanishing pressure is lower than
the corresponding one for unpaired magnetized strange quark
matter and, as the magnetic field increases, the energy per
baryon decreases. This implies that magnetized color flavor
locked matter is more stable and could become the ground state
inside neutron stars. The mass-radius relation for such stars
is also studied.
- Title of Poster Contribution (SMFNS2011) (proposal):
The Role of Isovector Mesons, Antikaon Condensates and
Strong Magnetic Fields in Pulsars
Aurora Pérez Martínez, Hugo Pérez Rojas, Daryel
Manreza Paret, Rosana Oliveira Gomes, Alexandre Mesquita,
Moisés Razeira and César Zen Vasconcellos
Abstract: In
this contribution we study the effects of isovector mesons,
antikaon condensates and strong magnetic fields in the
structure of pulsars. We consider, for this task, a phase
transition to nuclear matter containing an antikaon condensate
using an effective model with derivative couplings. Nucleon
fields interact in this formalism through the exchange of
sigma, omega, rho, and delta meson fields in the presence of a
background of electrons to accomplish electric charge
neutrality and beta equilibrium. As conventionally assumed,
Landau diamagnetism and Pauli paramagnetism interaction terms
are properly introduced in our lagrangian formalism in order to
consider the interaction of charged and neutral baryons with
the magnetic field. We then seek for stationary-state solutions
of the modified Dirac equation in the presence of strong
magnetic fields. In order to implement the phase transition we
use the Gibbs conditions combined with the mean-field
approximation, giving rise to a mixed phase of coexistence
between nuclear matter and the condensed of antikaons. Pulsar
rotation, in our approach, is implemented considering interior
solutions for the dragging frequency. Then we analyze the
consequences of our approach on already known properties of
nuclear matter, ie, the compression modulus, the effective
nucleon mass and the maximum neutron star mass predicted by
integrating the TOV equations as well as on rotation properties
of the pulsar.
- Carola Dobrigkeit
(Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil)
- Title of Talk (STARS2011): Recent results from the
Pierre Auger Observatory
Carola Dobrigkeit (for the
Pierre Auger Collaboration)
Abstract: The
Pierre Auger Observatory in Argentina is the largest cosmic ray
detector array ever built. Its main goal is to study cosmic
rays above 1 ~ 10 EeV. Although the construction of its
baseline design was completed in mid 2008, the Observatory is
taking data continuously since January 2004. The main results
obtained with the Pierre Auger Observatory will be presented,
with emphasis on the energy spectrum, composition and arrival
directions of the ultra-high energy cosmic rays. Features
observed in the energy spectrum will be discussed. Results
about the composition obtained from systematic studies of the
average depth of shower maximum and its fluctuations will be
reviewed. Recent results of studies of correlations with nearby
extragalactic objects, including evidences of an excess in the
direction of Centaurus A, will be presented.
- César Augusto Zen
Vasconcellos (Universidade Federal do Rio Grande do Sul
(UFRGS), Porto Alegre, Brazil)
- César A. Terrero
Escalante (Universidad de Colima, Colima, Mexico)
- Title of Talk (STARS2011):
Out of this World Darkness
César A. Terrero Escalante,
Leopoldo A. Pando Zayas and Norma Quiróz
Abstract: A
cosmological model is developed without exotic, unobservable
matter components in the effective 4-dimensional energy-stress
tensor. The model is based on the scenario of the so called
mirage cosmology. The accelerated expansions assumed to be
caused by the inflaton or the dark energy are consequences of
the motion of our universe (a D3-brane) in a 10-dimensional
type IIB supergravity background. In turn, the dark matter may
come from a hidden sector which couples to the matter in the
brane-universe only via higher-dimension operators.
- Christian Motch
(CNRS Observatoire Astronomique, Université de Strasbourg,
Strasbourg, France)
- Daryel Manreza Paret
(Instituto de Cibernética, Matemática y Física (ICIMAF), La Habana,
Cuba)
- Title of Talk (SMFNS2011):
Astrophysical Properties of Magnetized Quark
Stars
Daryel Manreza Paret and Aurora
Pérez Martínez
Abstract: This
work aims to study how amending certain astrophysical
observable of quark stars due to presence of magnetic field. We
will work using the phenomenological MIT Bag model. The
stability of the Magnetized Strange Quark Matter (MSQM) is
studied taking into account the variation of parameters from
the model: s quark mass, baryonic density, magnetic field and
the Bag parameter. Results obtained were compared with those of
magnetized normal quark matter (only u and d quarks in beta
equilibrium) as well as the Strange Quark Matter (SQM). It is
found that the energy per baryon decreases with the increasing
magnetic field which implies that the MSQM is more stable than
SQM. The Equations of State previously obtained are used to
obtain stable configurations of magnetized strange stars
checking that the magnetic field helps to reduce Mass-Radius
(M-R) ratio of the star.
- Debora Péres Menezes
(Universidade Federal de Santa Catarina (UFSC), Florianópolis,
Brazil)
- Title of Talk (STARS2011): Neutrino Opacities and the
Pasta Phase Structure
Debora Péres Menezes and M.D.
Alloy
Abstract: The
diffusion coefficients, related to the neutrino opacities, are
calculated considering the formation of nuclear pasta and
homogeneous matter at low densities. The obtained mean free
paths are significantly altered by the presence of nuclear
pasta in stellar matter when compared with the results obtained
with homogeneous matter. These differences in neutrino
opacities will influence the Kelvin-Helmholtz phase of
protoneutron stars and consequently the results of their
evolution.
- Title of Talk (SMFNS2011):
Finite Temperature Matter Subject to Strong Magnetic
Fields
Debora Péres Menezes, Sidney S.
Avancini and C. Providencia
Abstract: We
know that the energy per baryon of magnetized quark matter
becomes more bound than nuclear matter made of iron nuclei, for
a magnetic field around 2 X 1019 G. We use the mean
field approximation to investigate quark matter described by
the su(3) Nambu--Jona-Lasinio model subject to a strong
magnetic field both at zero and finite temperature.
- Donald B. Melrose
(School of Physic, The University of Sydney, Australia)
- Title of Talk (STARS2011):
Magnetic Explosions, with Application
to Magnetar Outbursts and to Solar Flares
Don Melrose
Abstract:
Magnetars are slowly rotating neutron stars with much stronger
magnetic fields than in normal pulsars. Magnetar outbursts
involve explosive release of magnetic energy. Two more familiar
examples of explosive magnetic energy release are in solar
flares and magnetospheric substorms. In this talk I will
concentrate on the similarities between these phenomena,
arguing that they are three examples of "magnetic explosions".
Magnetic explosions need to be understood on at least three
different scales: a global scale, that determines the
energetics; a macro scale that involves separate energy-release
and particle-acceleration regions and propagation between them;
and a micro scale on which collisionless dissipation occurs.
- Title of Talk (SMFNS2011):
Dispersion in a Spin-dependent Magnetized Relativistic
Quantum Electron Gas
Don Melrosse
Abstract: An
electron gas in a magnetic field can be magnetised due to a
preferred alignment of the spins. The response of such an
electron gas to an electromagnetic perturbation leads to a
spin-dependent contribution to the dielectric tensor. The
properties of the wave modes of a cold spin-dependent electron
gas are derived using a quasi-classical theory based on the BMT
equation. The spin-dependent result is calculated exactly using
Dirac's equation for a magnetized electron. The approximations
that need to be made to reduce the general result to the
quasi-classical case are discussed.
- Eduardo Guendelman
(Ben Gurion University, Negev, Israel)
- Title of Talk (STARS2011):
Bags and Confinement Governed by S.S.B. of Scale
Invariance
Eduardo Guendelman
Abstract: A
general coordinate invariant theory is constructed where
confinement of gauge fields and gauge dynamics in general is
governed by the spontaneous symmetry breaking (s.s.b.) of scale
invariance. The model uses two measures of integration in the
action, the standard (√-g), where g is the determinant of
the metric and another measure, Phi, independent of the metric.
To implement scale invariance (S.I.), a dilaton field is
introduced. Using the first order formalism, curvature (Phi.R
and (√-g) R2)) terms, gauge field term and
dilaton kinetic terms are introduced in a conformally invariant
way. Exponential potentials for the dilaton break down (softly)
the conformal invariance down to global scale invariance, which
also suffers s.s.b. after integrating the equations of motion.
The model has a well-defined flat space limit. As a result of
the s.s.b. of scale invariance phases with different vacuum
energy density appear. Inside the bags, that is in the regions
of larger vacuum energy density, the gauge dynamics is normal,
that is non-confining, while for the region of smaller vacuum
energy density, the gauge field dynamics is confining.
Likewise, the dynamics of scalars, like would be Goldstone
bosons, is suppressed inside the bags.
- Title of Talk (SMFNS2011):
Cosmic Analogues of the Stern-Gerlach Experiment and
the Detection of Light Bosons
Author: Eduardo Guendelman
Abstract: We
show that, by studying the arrival times of radio pulses from
highly-magnetized pulsars, it may be possible to detect light
spin-0 bosons (such as axions and axion-like particles) with a
much greater sensitivity, over a broad particle mass range than
is currently reachable by terrestrial experiments and indirect
astrophysical bounds. In particular, we study the effect of
splitting of photon-boson beams under intense magnetic field
gradients in magnetars and show that radio pulses (at meter
wavelengths) may be split and shift by a discernible phase down
to a photon-boson coupling constant of g ~ 1e-14
[1/GeV]; i.e., about four orders of magnitude lower than
current upper limits on g. The effect increases linearly with
photon wavelength with split pulses having equal fluxes and
similar polarizations. These properties make the identification
of beam-splitting and beam deflection effects straightforward
with currently available data. Better understanding of radio
emission from magnetars is, however, required to confidently
exclude regions in the parameter space when such effects are
not observed.
- Elizabeth Rodrigues
Querts (Instituto de Cibernética, Matemática y Física
(ICIMAF), La Habana, Cuba)
- Title of Talk (SMFNS2011): About QED Magnetized
Vacuum Decay in Large Fields
Elizabeth Rodrigues Querts and Hugo Pérez
Rojas
- Title of Poster Contribution (SMFNS2011):
Self-magnetization in Electroweak Vacuum and in Very
Dense Systems
Elizabeth Rodriguez Querts and H. Perez
Rojas
Abstract: For
charged vector bosons (W bosons) of mass MW , their
vacuum energy density diverges for some B=Bc where
Bc is a critical value, leading to a instability.
The vacuum magnetization also diverges for B →
Bc which suggests that if the magnetic field is
large enough, it can be self-consistently maintained, and this
mechanism actually prevents B from reaching the critical
unstable value Bc. For neutral vector bosons bearing
an anomalous magnetic moment, the instability of the ground
state is produced also for some critical field. We discuss
these models in connection to the case of radiation in
equilibrium at high temperature (T~ mc2) coexisting
with hot magnetized electron-positron pairs. Their bosonization
would lead to physical conditions for the applicability of the
previous neutral bosons model to describe a possible
self-magnetization of the system.
- Eloy Ayón Beato
(Centro de Investigación y de Estudios Avanzados del Instituto
Politécnico Nacional (CINVESTAV), Ciudad de México, México)
- Title of Talk (STARS2011): Analytic Lifshitz Black
Holes in Higher Dimensions
Eloy Ayón Beato
Abstract: We
generalize the four-dimensional R2-corrected z=3/2
Lifshitz black hole to a two-parameter family of black hole
solutions with asymptotic Lifshitz symmetry for any dynamical
exponent z and for any dimension D. For a particular relation
between the parameters, we find the first example of an
extremal Lifshitz black hole. An asymptotically Lifshitz black
hole with a logarithmic decay is also exhibited for a specific
critical exponent depending on the dimension. Additionally, we
show how to generalize the two-parameter family of black holes
to include other horizont topologies. We extend this analysis
to the more general quadratic curvature corrections for which
we present three new families of higher-dimensional D≥5
analytic Lifshitz black holes for generic z. One of these
higher-dimensional families contains as critical limits the z=3
three-dimensional Lifshitz black hole and a new z=6
four-dimensional black hole. The variety of analytic solutions
presented here encourages exploring these gravity models within
the context of non-relativistic holographic correspondence.
- Title of Talk (SMFNS2011): Nonlinearly Charged
Regular Black Holes
Eloy Ayón Beato
Abstract: It is
clear now that black holes are not necessarily singular. We
review some of the aspects that led to this conclusion,
allowing the discovery of the first regular exact black hole
solutions by means of nonlinearly charged sources.
- Ernesto Kemp
(Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil)
- Title of Talk (STARS2011):
Extracting Limits for the Diffuse Non-Electron Neutrino
Flux from SNO Data
Bruno Miguez, Orlando L.G. Peres, Ernesto
Kemp
Abstract: There
is a predicted diffuse neutrino flux originated by all
supernova already exploded in the past. This flux is weighted
by stellar formation and supernovae occurrence rates. The
expected energy spectrum of these neutrinos differs from those
from recent supernova mainly by their energy
“redshift” due the expansion of the universe. Thus,
despite the fact that one single supernova is a transient
state; their cumulative effect produces a steady flux of
diffuse neutrinos everywhere in universe. These neutrinos have
never been observed before. Only upper limits on their fluxes
have been reported by the collaborations operating neutrino
telescopes. The SNO experiment published an analysis where the
total flux of diffuse electron neutrinos has an upper limit of
φe ≤ 61-93 cm-2.s-1, depending on
a specific supernova model. At the present, the best limit for
the diffuse flux of non-electron neutrinos is φx ≤ 10³
cm-2.s-1, resulted from an analysis of
the Super-Kamiokande data. In this work we have extended the
SNO analysis including the elastic scattering on electrons via
neutral current interactions to extract information on diffuse
flux of the non-electron neutrino flavors (i.e. muon and tau
neutrinos). Our analysis yield as limits to non-electron
neutrinos flux above to 21 MeV φx ≤ (2.1-17) 10³
cm-2.s-1 and φx ≤ (6.5-23) 10³
cm-2.s-1 as limit to non-electron
antineutrinos flux.
- Title of Poster Contribution
(STARS2011): Estimating the Distances of Stellar
Collapses in the Galaxy Analyzing the Energy Spectrum of
Neutrino Bursts
Ernesto Kemp, Bruno Miguez and Walter
Fulgione
Abstract: There
is a rather good consensus both in theoretical and experimental
basis, coming from observations of the SN1987A, that a
supernova explosion is preceded by a huge flux of neutrinos
from the three flavors and their antiparticles. In principle,
large neutrino telescopes are able disentangle the neutrino
burst signal from the background fluctuations. If a minimum
number of collected events is enough to build the energy
spectrum, further analysis can be carried out to get spectrum
parameters providing astrophysical information from the
innermost regions of the collapsed object. In this work we show
some preliminary results about the method we are proposing to
determine the distance from the collapsing star, using only the
information of the spectral shape from expected antinu-e events
on neutrino telescopes, such as the LVD at the LNGS - Italy,
and assumptions on the total binding energy of the stellar core
released in the collapsing process. In this preliminary phase
we focus the discussion on the errors of the method related to
the theoretical uncertainties concerning the energy released in
the formation of the compact object resulting from the
collapse.
- Title of Talk (SMFNS2011):
Wavelets Applied to the Detection of Point Sources of
UHECRs
Rafael Alves Batista, Ernesto Kemp, Bruno Daniel and
Rogério M. de Almeida
Abstract: In
this work we analyze the effect of smoothing sky maps
containing arrival directions of cosmic rays with a Gaussian
kernel and also kernels of the Mexican hat wavelets of orders
1, 2 and 3. The analysis were performed by calculating the
amplification of the signal-to-noise ratio for several
background patterns (noise) and different number of events
coming from a simulated source (signal). In the simulations we
have considered different scenarios of UHECRs detection, for
instance an ideal detector capable of observing the full sky
with equal probability in all directions as well as a detector
with limited acceptance law (a standard formulation
sin(theta)*cos(theta) ). The geographical position of our
virtual detector was chose to optimize its exposure to the sky.
The results are discussed in terms of signal/noise ratio
achieved for different angular scales and the effects of the
limited acceptance of the detector in comparison of a
homogeneous coverage of the sky.
- Ernesto López Fune
(Instituto de Cibernética, Matemática y Física (ICIMAF), La Habana,
Cuba)
- Title of Talk (SMFNS2011): Magnetized Strangelets at
Finite Temperature
Ernesto López Fune
Abstract: The
main properties of magnetized strangelets such as the energy
per baryon, radii and electric charge are studied. Temperature
effects are also taken into account, in order to study their
stability compared to the 56Fe isotope and
non-magnetized strangelets using the Liquid Drop Model. Massive
quarks are considered with the aim to have a more realistic
description for strangelets in the astrophysical context, and
also the environment of heavy ion colliders, playing an
important role in the thermodynamical magnitudes of the quark
gas. The presence of a magnetic field, tends to stabilize more
strangelets, even when temperature effects are taken into
account. MSQM strangelets in a paired superconductor phase, are
also studied, where we also checked that they are more stable
than ordinary MSQM strangelets for a typical gap of 100 MeV.
- Felix Mirabel
(Commissariat a l'Energie Atomique (CEA), France and CONICET,
Argentina)
- Title of Talk (STARS2011): Astrophysical Black Holes
and their Role in Cosmic Evolution
Felix Mirabel
Abstract: I
will review the present status of the observations of
astrophysical black holes (stellar and supermassive), with
particular emphasis on the relativistic phenomena.
- Title of Talk (SMFNS2011): The Role of Black Holes in
Cosmic Evolution
Felix Mirabel
Abstract: I
will show that feedback in the form of high energy radiation,
jets and massive winds from accreting black holes played
important roles in the re-ionization epoch of the universe, as
well as in the formation of galaxies of all mass scales.
- Fernando Silveira
Navarra (Universidade de São Paulo (USP), São Paulo,
Brazil)
- Title of Talk (STARS2011): Gluon Condensates in Dense
Stars
Fernando S. Navarra and David A. Fogaça
Abstract: Quark
gluon plasma with high chemical potential and almost zero
temperature may exist in the core of compact stars. Most likely
it is a strongly interacting system. The strong interactions
may be partly due to non-perturbative effects, which survive
after the deconfinement transition and which can be related
with the non-vanishing gluon condensates in the sQGP. In this
work, starting from the QCD Lagrangian we perform a gluon field
decomposition in low ("soft") and high ("hard") momentum
components, we make a mean field approximation for the hard
gluons and take the matrix elements of the soft gluon fields in
the plasma. The latter are related to the condensates of
dimension two and four. With these approximations we derive an
analytical expression for the equation of state, which is
compared to the MIT bag model one. The effect of the
condensates is to soften the equation of state whereas the hard
gluons significantly increase the energy density and the
pressure.
- Genly Leon Torres
(Universidade Central Marta Abreu de Las Villas,
Cuba) -
- Title of Talk (STARS2011): Phase Space of Anisotropic
Rn Cosmologies
Genly Leon Torres and Emmanuel N
Saridakis
Abstract: We
construct general anisotropic cosmological scenarios governed
by an f(R) gravitational sector. Focusing then on some specific
geometry in the case of Rn-gravity, and modeling the
matter content as a perfect fluid, we perform a detailed
phase-space analysis. We analyze the possibility of
accelerating expansion at late times, and additionally, we
determine conditions for the parameter n for the existence of
phantom behavior, contracting solutions as well as of cyclic
cosmology. Furthermore, we analyze if the universe evolves
torwards the future isotropization. This result has been
achieved by us for Kantowsky-Sachs geometries without relying
on a cosmic no-hair theorem. Our results indicate that
anisotropic geometries in modified gravitational frameworks
present radically different cosmological behaviors compared to
the simple isotropic scenarios.
- German Lugones
(Universidade Federal do ABC (UFABC), Santo André, Brazil)
- Title of Talk (STARS2011): Quark Matter Deconfinement
in Compact Stars
German Lugones
Abstract: In
this work we present new results on the deconfinement
transition in old neutron stars and in protoneutron stars. We
impose color and flavor conservation during the transition in
such a way that just deconfined quark matter is transitorily
out of equilibrium with respect to weak interactions. The
hadronic phase is described through a relativistic mean field
model and quark matter through the Nambu-Jona-Lasinio model and
the MIT Bag model. We study the effect of color
superconductivity and neutrino trapping on the critical density
for deconfinement. We explore some astrophysical consequences
of the results, in particular, the possible generation of short
gamma ray bursts.
- Hugo Celso Pérez
Rojas (Instituto de Cibernética, Matemática y Física
(ICIMAF), La Habana, Cuba)
- Title of Talk (SMFNS2011): Photon Redshift in a
Magnetic Field
Hugo Celso Pérez Rojas, Elizabeth Rodriguez Querts
and José Helayel Netto
Abstract:
Previous results concerning the arising a tiny photon anomalous
paramagnetic moment are also interpreted as a red-shift in
analogy to the gravitational known effect. It is due to the
photon interaction with the magnetized virtual
electron-positron background which withdraws transverse
momentum from photons and is polarization-dependent. The photon
frequency red-shift implies a change in time and a clock would
go faster for increasing magnetic field intensity
- Title of Poster Contribution
(SMFNS2011) (proposal): Naturalness and Magnetic
Constraining of the Equation of State of the Double Pulsar
J07373039
Hugo Pérez Rojas, Aurora Pérez Martínez, Daryel
Manreza Paret, Rosana Oliveira Gomes, Alexandre Mesquita,
Moisés Razeira and César Zen Vasconcellos
Abstract: We
investigate the role of naturalness and magnetization in an
extended version of the parametric coupling effective model
which includes the whole fundamental baryon octet and genuine
many-body forces simulated by nonlinear self-couplings and
meson-meson interaction terms involving scalar-isoscalar,
vector-isoscalar, vector-isovector and scalar-isovector meson
fields. Additionally, in order to describe the properties of
neutron stars, the lagrangian density of the model includes the
light lepton fields, which are essential to accomplish in the
star charge neutrality and chemical equilibrium. In the
framework of this parametric coupling Lagrangian model, we use
our knowledge about the gravitational and baryon masses as well
as on the intensity of the magnetic field of pulsar B of the
double pulsar J07373039 to place constraints on the equation of
state of nuclear matter under the assumption that pulsar B is
formed in an electron-capture supernova event. With this aim,
as a new formal feature, we introduce a systematic theoretical
procedure to include many body nuclear interaction components
in relativistic effective theories with derivative couplings in
the presence of intense magnetic fields. Using recent
observational data related to the gravitational and baryon
masses of pulsar B of the double pulsar J07373039 as well as on
its surface magnetic field, we impose new constraints on the
mathematical parameters of the model, restricting and testing
our parametric coupling approach in a broad range of values.
Upon adjusting the parameters of the theory in order to
describe bulk static properties of ordinary nuclear matter, we
show that our approach represents a natural modeling of dense
matter under the extreme physical conditions found in the
interior of neutron stars. We then use the resulting approach
to describe global static properties as well as the
gravitational and baryon masses of neutron stars. Our
predictions indicate an intimate connection between the
criterion of naturalness and the exhaustion of the phase space
of meson fields and genuine many-body forces: the addition of
the whole fundamental baryon octet and many-body forces
simulated by nonlinear self-couplings and meson-meson
interaction terms improves the scope and the degree of
naturalness of our effective model. On basis of our results, we
advocate that naturalness plays a fundamental role in effective
field theory and may represent a relevant criterion for model
selection in the description of the properties of neutron
stars.
- Ignacio Francisco
Ranea-Sandoval (Facultad de Ciencias Astronómicas y
Geofísicas, Universidad Nacional de La Plata, La Plata, Argentina)
- Title of Poster Contribution (STARS2011):
Instabilities in Kerr Spacetimes
Gustavo Dotti, Reinaldo J. Gleiser and Ignacio
Francisco Ranea Sandoval
Abstract: In
this work we generalize previous results regarding the
stability under gravitational perturbations (s = ± 2) of
super-extreme Kerr space-time which has a naked singularity and
black hole interior beyond the Cauchy horizon. To do so we
study solutions to the radial and angular Teukolsky's equations
with different spin weight, particularly s= ±1 representing
electromagnetic perturbations, s = ± 1/2 representing a
perturbation by a Dirac field and s=0 representing
perturbations by a scalar field. By analyzing the properties of
radial and angular eigenvalues we prove the existence of an
infinite family of unstable modes.
- Title of Poster Contribution (SMFNS2011):
Magnetars as Highly Magnetized Quark Stars: an
analytical treatment
Milva Orsaria, Ignacio Francisco Ranea Sandoval and
Héctor Vucetich
Abstract: We
present an analytical model of a magnetar as a high density
magnetized quark bag. The effect of strong magnetic fields (B
> 5 1016 G) in the equation of state is
considered. An analytic expression for the Mass-Radius
relationship is found from the energy variational principle in
general relativity. Our results are compared with observational
evidences of possible quark and/or hybrid stars.
- Ignatios Antoniadis
(Theory Division of CERN in Geneva, Switzerland)
- Title of Talk (STARS2011): Physics from Extra
Dimensions
Ignatios Antoniadis
- Jason Nordhaus
(Princeton University, Princeton, USA)
- Title of Talk (SMFNS2011): Formation of High-Field
Magnetic White Dwarfs from Common Envelopes
Jason Nordhaus
Abstract: The
origin of highly magnetized white dwarfs has remained a mystery
since their initial discovery. Recent observations indicate
that the formation of high-field magnetic white dwarfs is
intimately related to strong binary interactions during
post-main-sequence phases of stellar evolution. If a low-mass
companion, such as a planet, brown dwarf, or low-mass star, is
engulfed by a post-main-sequence giant, gravitational torques
in the envelope of the giant lead to a reduction of the
companion’s orbit. Sufficiently low-mass companions
in-spiral until they are shredded by the strong gravitational
tides near the white dwarf core. Subsequent formation of a
super-Eddington accretion disk from the disrupted companion
inside a common envelope can dramatically amplify magnetic
fields via a dynamo. Here, we show that these disk-generated
fields are sufficiently strong to explain the observed range of
magnetic field strengths for isolated, high-field magnetic
white dwarfs. A higher-mass binary analogue may also contribute
to the origin of magnetar fields.
- Javier Pardo Vega
(Facultad de Física, Universidad de La Habana, Cuba)
- Title of Poster Contribution (SMFNS2011): Photon
Propagation in Casimir Vacuum
Javier Pardo Vega and Hugo Pérez Rojas
Abstract: By
starting from the formal analogy with the temperature case, the
dispersion equations for photons in a Casimir cavity are
studied. The eigenvalues and eigenvectors are found in an
approximation independent form. It is found two different
eigenvalues and three eigenmodes. By using one-loop
calculations, physical consequences are discussed.
- Joerg Aichelin
(Université de Nantes/SUBATECH, Nantes, France)
- Title of Talk (STARS2011): Kaon Condensates
Joerg Aichelin
- Title of Talk (SMFNS2011): News from Kaons in
Matter
Joerg Aichelin, C. Hartnack and A. Sood
Abstract: We report about the recent findings in heavy ion
experiments which explicitly exclude Kaon condensates at
densities lower than 3ρ0.
- Jonathan Braithwaite
(Universitaet Bonn, Bonn, Germany))
- Title of Talk (SMFNS2011): Magnetic Deformation of
Neutron Stars and Gravitational Radiation
Jonathan Braithwaite
Abstract: The
magnetic field inside a star affects the mass distribution
which, assuming the field is not symmetrical about the rotation
axis, gives rise to the emission of gravitational radiation. I
discuss simulations of various magnetic equilibrium, the
induced change to the moments of inertia, and possible other
observables such as the energy of supernovae and the angle of
inclination between magnetic and rotation axes.
- Jorge Alfaro
(Pontifícia Universidad Católica de Chile (PUC), Santiago, Chile)
- Title of Talk (STARS2011): Delta Gravity and Dark
Energy
Jorge Alfaro
Abstract: We
present a model of the gravitational field based on two
symmetric tensors. Outside matter, the predictions of the model
coincide exactly with General Relativity, so all classical
tests are satisfied. In Cosmology, we get accelerated expansion
without a cosmological constant.
- Title of Talk (SMFNS2011): Gauge Invariant
Electrodynamics Motivated by a Spontaneous Breaking of the
Lorentz Symmetry
Jorge Alfaro
Abstract: We
introduce a new version of non-linear electrodynamics which is
produced by a spontaneous symmetry breaking of Lorentz
invariance induced by the non-zero expectation value of the
gauge invariant electromagnetic field strength. The symmetry
breaking potential is argued to effectively arise from the
integration of massive gauge bosons and fermions in an
underlying fundamental theory. All possible choices of the
vacuum lead only to the remaining invariant subgroups T(2) and
HOM(2). We explore in detail the plane wave solutions of the
linearized sector of the model for an arbitrary vacuum. They
present two types of dispersion relations. One is the usual
one, with fields similar to the Maxwell fields. The other
dispersion relation involves anisotropies determined by the
structure of the vacuum. The corresponding fields reflect these
anisotropies. The model is stable in the small Lorentz
invariance violation approximation. We have also embedded our
model in the photon sector of the Standard Model Extension, in
order to translate the many bounds obtained in the latter into
corresponding limits for our parameters. The one-way
anisotropic speed of light is calculated for a general vacuum
and its isotropic component is strongly bounded by \tilde
\delta c/c < 2 X 10-32. The anisotropic violation
contribution is estimated by introducing an alternative
definition for the difference of the two-way speed of light in
perpendicular directions, \Delta c, that is relevant to
Michelson-Morley type of experiments and which turns out to be
also strongly bounded by \Delta c/c < 10-32.
Finally, we speculate on the relation of the vacuum energy of
the model with the cosmological constant and propose a
connection between the vacuum fields and the intergalactic
magnetic fields.
- Jorge Armando Rueda
Hernandez (Università degli Studi di Roma "La Sapienza",
Roma, Italy)
- Title of Talk (STARS2011):
Neutron Star Equilibrium Configurations including Weak,
Electromagnetic and Strong Interactions within General
Relativity
Jorge Armando Rueda Hernandez, Remo Ruffini and
She-Sheng Xue
Abstract: The
equilibrium equations of neutron stars including weak,
electromagnetic and strong interactions within general
relativity are presented and solved numerically. It is
emphasized the crucial role of the constancy of the generalized
Fermi energies of particles in determining the core-crust
boundary conditions.
- Jorge E. Horvath
(Instituto Astronômico e Geofísico da Universidade de São Paulo
(IAG/USP), São Paulo, Brazil)
- Title of Talk (STARS2011): Open Problems
Jorge E. Horvath
- Title of Talk (STARS2011): The Mass Distribution of
Neutron Stars
Jorge E. Horvath, R. Valentim and E.
Rangel
- Title of Talk (SMFNS2011): Final Discussion (Round
Table)
Jorge E. Horvath
- Title of Talk (SMFNS2011): Self-bound Stars are/are
not Severely Limited by New Data
Laura Paulucci, M.G.B. de Avellar and Jorge E.
Horvath
- José Antonio de Freitas
Pacheco (Observatoire de la Côte d'Azur (OCA), Nice,
France)
- Title of Talk (STARS2011): The Evolution of the
Distribution of Baryons in the Universe from Cosmological
Simulations
José Antonio de Freitas Pacheco and F.
Durier
Abstract:
Baryons are found locked in stars and in a gaseous phase
forming the interstellar gas and the intergalactic medium. The
fraction of hydrogen and metals in these different components
evolves in time, reflecting the action of different processes
like star formation and feedback either from supernovae and
AGNs. The evolution of these different components resulting
from cosmological simulations will be reported and compared
with recent observational data.
- Karl Jansen ( NIC,
DESY, Zeuthen, Germany)
- Title of Talk (STARS2011): The Strange Content of the
Nucleon
Karl Jansen
Abstract: We
give an overview about lattice computations of the strange
quark content of the nucleon. Such calculations are important
for super-symmetric dark matter scenarios.
- Title of Talk (SMFNS2011): Strange Quark
Physics
Karl Jansen
Abstract:
Various aspects of strange quark physics as computed from
lattice calculations are discussed. Topics include the strange
quark mass, decay constants and meson and baryon masses.
- Karsten Jedamzik
(University of Montpellier, France)
- Title of Talk (STARS2011): Big Bang
Nucleosynthesis
Karsten Jedamzik
Abstract: The
status of Big Bang nucleosynthesis is discussed. After
establishing that their is a factor three-five discrepancy
between the predicted and observationally inferred primordial
7Li abundance, I discuss possible stellar physics,
nuclear physics, and physics beyond the standard model
resolutions to this problem.
- Kuantay Boshkayev (Università degli Studi di
Roma "La Sapienza", Roma, Italy)
- Title of Poster Contribution (STARS2011): On the
Minimum Rotation Period of Rotating White Dwarfs
Kuantay Boshkayev, Jorge Rueda, and Remo
Ruffini
Abstract: The
properties of rotating white dwarfs are calculated within the
framework of general relativity. The Hartle-Thorne formalism is
applied to construct self-consistently the internal and the
external solution to the Einstein equations. Within this
formalism we calculate the mass, the radius, the moment of
inertia, the eccentricity and the quadrupole moment of rotating
white dwarfs as a function both of the central density and the
rotational period of the star. The minimum rotation period
(maximum angular velocity) for stable configurations has been
obtained as well as the contribution of rotation to the maximum
mass of white dwarfs.
- Lauro Tomio
(Universidade Federal Fluminense (UFF), Niterói, Brazil)
- Title of Talk (STARS2011): Exotic Carbon Systems in
Two-neutron Halo Three-body Models
Lauro Tomio, Antonio Delfino, M. T. Yamashita, and
Tobias Frederico
Abstract:
Within a renormalized zero-ranged three-body model, we discuss
the general properties of exotic carbon systems, considering
them as a core with two-neutron halo. The qualitative
properties of such systems can be studied within a three-body
model with a s-wave zero-range interaction, suitable for large
two-body scattering lengths, or weakly bound subsystems. The
low-energy properties of large three-body systems are universal
and dominated by the Efimov effect, where the details of the
interaction are less important. The three-body properties are
set by low-energy parameters (scales), as the binding energy of
the halo to the core, which is assumed to be structureless, and
the corresponding scattering lengths of the two-body
subsystems. The condition for the appearance of one excited
state in the maximally symmetric configuration of a three-body
halo system in the Efimov limit (infinite scattering lengths)
defines a universal map. The boundary separates a region in the
parametric space where excited states are possible. By crossing
the critical boundary, a bound subsystem becomes a virtual
state. We study the particular case of Carbon-20, modeled as
n-n-Carbon-18 system, where Carbon-19 is bound; and also the
Carbon-22, which is a Borromean system with all subsystems
unbound.
- Liuba Peñate
(Universidad Central de Las Villas, Santa Clara, Cuba)
- Title of Poster Contribution (SMFNS2011):
Environmental Effects of Flares from Red Dwarf
Stars
Liuba Peñate, Rolando Cárdenas and Osmel
Martín
Abstract: We
examine some environmental effects appearing on exoplanets in
the habitable zone of red dwarfs, during the first billion
years of the star evolution. We focus on the radiative
perturbation that the frequent stellar flares would cause on
the planet surface and down the assumed planetary ocean, with
some insight on the affectation of potential life forms.
- Luciano Rezzolla
(Albert Einstein Institute, Max Planck Institute for Gravitational
Physics, Potsdam, Germany)
- Title of Talk (STARS2011): Modeling the Inspiral and
Merger of Binary Neutron Stars
Luciano Rezzolla
Abstract:
Investigating the final evolution of neutron stars binaries
promises to be particularly rewarding. These systems are in
fact excellent sources of gravitational waves, they are thought
to behind the powerful engines powering short gamma-ray bursts,
and they can unveil the behaviour of matter at extreme
densities and temperatures. I will review the present
understanding in the modeling the inspiral and merger of binary
neutron stars in full general relativity, underlining the
considerable recent progress both in hydrodynamics and in MHD.
Finally, I will discuss the steps that still need to be taken
to use this progress to model the central engine of short
gamma-ray bursts.
- Luis Antonio Cabral
(Universidade Federal de Tocantins (UFT), Palmas, Brazil)
- Title of Poster Contribution (STARS2011): Conserved
Quantities and Dualities for Particles in Curved
Spacetime
Luis Antonio Cabral
Abstract: We
consider particles moving in curved spacetime and symmetries in
such gravitational background. According to spacetime
isometries, we obtain the Killing vectors corresponding to a
specific spacetime metric. We use a generalized Killing
equation and search for solutions involving Killing tensors
associated with the metric. With these tensors some conserved
quantities are constructed and they are valid along particles
geodesic. In the Hamiltonian formalism for these particles, the
conserved quantities can generate a dual description of the
metric. We construct nontrivial dual metrics and consider a
kind of geometric duality that involves completely different
spacetimes. From these metrics we consider geometric invariants
and examine the singularity structure of the dual spacetime.
- Magno V.T. Machado
(Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre,
Brazil)
- Title of Talk (STARS2011): Geometric Scaling in
Ultrahigh Energy Neutrinos and Nonlinear Perturbative
QCD
Magno V.T. Machado
Abstract: It is
shown that in ultrahigh energy inelastic
neutrino-nucleon(nucleus) scattering the cross sections for the
boson-hadron(nucleus) reactions should exhibit geometric
scaling on the single variable tauA
=Q2/Q2sat,A. The dependence on energy and atomic
number of the charged/neutral current cross sections are
encoded in the saturation momentum Qsat,A. This fact
allows an analytical computation of the neutrino scattering on
nucleon/nucleus at high energies, providing a theoretical
parameterization based on the scaling property.
- Marcus Bleicher
(Institut für Theoretische Physik, Universitaet Frankfurt, Germany)
- Title of Talk (STARS2011): Micro Black Holes in the
Laboratory
Marcus Bleicher
Abstract: We
present a short overview on the ideas of large extra-dimensions
and their implications for the possible production of micro
black holes in the next generation particle accelerators, e.g.
the LHC at CERN. In fact, the possibility of black hole
production on earth is currently one of the most exciting
predictions for the LHC accelerator and would change our
current understanding of physics radically. We will also
discuss possible other observables for colliders and for cosmic
ray physics.
- Martin Sprenger
(Institut für Theoretische Physik, Universitaet Frankfurt, Germany)
- Title of Poster Contribution (STARS2011): Neutrino
Oscillations as a Novel Probefor a Minimal Length
Martin Sprenger, P.Nicolini and
Marcus Bleicher
Abstract: In
quantum gravity, the smooth picture of space-time we are
familiar with should be replaced by a space-time that is
subject to quantum fluctuations. Even though no complete
description yet exists, most candidate theories of quantum
gravity agree on the emergence of a minimal length at the
fundamental scale. Structures smaller than this length scale
lose operational meaning which introduces radical changes in
particle and black hole physics. In this talk, we present a
phenomenological, model-independent description of the effects
of a minimal length and propose neutrino oscillations as a
viable probe for these effects.The modifications of the
oscillation probabilities allow a comparison with experimental
data and we will present bounds on the value of the minimal
length.
- Miriani G. Pastoriza
(Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre,
Brazil)
- Title of Talk (STARS2011): The Eco-system of Active
Galactic Nuclei: perspective from the Infrared light
Miriani G. Pastoriza, Rogeiro Riffel and Dinalva
Sales
Abstract: The infrared spectral
region is a very adequate window to study the eco-system formed
by the stars, ionized and molecular gas, and the super-massive
black hole hosted in the central few parsecs of active galactic
nuclei. From image and spectroscopic observations we searched
the chronology of the star formation events and its connection
with the central energy source. The observed continuum emission
in the Near Infrared ( 0.8- 2.4 µm) together with the Silicates
absorption at 10 µm, is used to determine the geometry and
dimension of the dusty torus, which hide the accretion disk and
the ionized turbulent clouds of Seyfert 1 galaxies. The
chemical composition and physical conditions of the dust are
derived from the observation of the Polycyclic Aromatic
Hydrocarbons emission bands at 6.2μm, 7.7μm, 8.6μm,
11.2μm and 12.7μm. Finally the role played by the
accretion (dust, gas and stars) and interaction between
galaxies is analyzed as a mechanism to feed and grow the
central super-massive Black Hole.
- Moisés Razeira
(Universidade de Caxias do Sul (UCS), Caxias do Sul, Brazil)
- Title of Poster Contribution (STARS2011) (proposal):
A Relativistic Effective Model with Parameterized
Couplings for Neutron Stars
Moisés Razeira, Alexandre Mesquita, and César Zen
Vasconcellos
Abstract: We
present a relativistic effective model with derivative
couplings which includes genuine many-body forces simulated by
nonlinear interaction terms involving scalar-isoscalar,
vector-isoscalar, vector-isovector, scalar-isovector mesons.
The effective model presented in this work has a philosophy
quite similar to the original version of the model with
parameterized couplings. But unlike that, in which the
parametrization is directly inserted in the coupling constants
of the Glendenning model, we present here a method for the
derivation of the parametric dependence of the coupling terms,
in a way that allows in one side to consistently justify this
parametrization and in the other to extend in a coherent way
the range of possibilities of parameterizations in effective
models with derivative couplings. The extended model is then
applied to the description of neutron stars.
- Title of Poster Contribution (STARS2011) (proposal):
Dispersion Relations for Gluononium
Moisés Razeira,
Alexandre Mesquita, Marcos Rodriguez, Mário Luiz Lopes da
Silva, Francisco Fernández, and César Zen
Vasconcellos
Abstract: We
investigate relativistic bound states for a hypothetical light
scalar gluino pair (gluinonium), in the framework of the
covariant Bethe-Salpeter equation (BSE). In this paper, we
derive, from the covariant BSE for a fermion-anti-fermion
system, using charge conjugation, the corresponding bound-state
equation for a gluino pair and we then formulate, for a static
harmonic kernel the coupled differential equations for the
corresponding static Bethe-Salpeter amplitude. The steps of our
approach then include a numerical solution of the
Bethe-Salpeter amplitude for a two-body interaction consisting
of scalar, pseudo-scalar, and four-vector components and the
determination of the energy spectrum for the ground and the
radially excited states of massive gluinonium. We found the
energy spectrum and radial distributions of fundamental and
excited states of gluinonium. Our results show striking
similarities of two non relativistic constituent quark
model.
- Title of Poster Contribution (STARS2011) (proposal):
Neutron Stars as Dark Matter
Moisés Razeira, Alexandre Mesquita, José Eduardo
Costa, César Zen Vasconcellos, and Francisco
Fernández
Abstract: We
examine theoretical possibilities of extending the range of
maximum and minimum mass values of stable configurations of
neutron stars and pulsars using Le Chatelier Principle. Guided
by the ``observed'' values of hadronic masses of dark matter
(MACHOs), we go one step beyond other hadrodynamics approaches
still studying global properties of possible sequences of
compact stars in hydrostatic equilibrium. Our treatment leads
to equilibrium configurations whose properties are more complex
than those predicted by other treatments. Using an extended
version of the effective relativistic parameterized coupling
model we determined the limits of stable configurations of
neutron stars and pulsars by considering different possible
choices of effective parameters, enlarging the scope of the
theory and the presence of mesons of the light and heavy
sectors as well as nucleons, hyperons and leptons. We find in
this work stable configurations of neutron stars with masses
larger than 2 times the solar mass. These objects, when present
in sufficient quantities in the halo of the galaxy, could be
observed through the gravitational microlensing method as dark
matter.
- Osmel Martín
(Universidad Central de Las Villas, Santa Clara, Cuba)
- Title of Poster Contribution (SMFNS2011): Effects of
Galactic Gamma Ray Bursts on Planetary Atmospheres and
Biospheres
Osmel Martín, Rolando Cárdenas Ortiz, Jorge Horvath
and Liuba Peñate
Abstract: We
examine the effects that a galactic gamma ray burst would cause
on planetary atmospheres with and without ultraviolet
screeners. We assume a spectrum of the gamma ray burst coming
from a massive star and use a radiative transfer model in the
atmospheres considering mainly photo-absorption and Compton
scattering. Then we focus on the re-emission of aurora like
spectra due to the action of secondary electrons and finally
estimate the distances at which highly evolved massive stars
can be dangerous for planetary atmospheres and biospheres.
- Ovidiu Tesileanu
(University of Bucharest, Romania)
- Title of Talk (SMFNS2011): Magnetic Fields and
Radiative MHD Simulations of YSO Jets
Ovidiu Tesileanu, Silvano Massaglia, and Andrea
Mignone
Abstract:
During star formation, there is a phase when the emission of
jets is likely to occur. Many efforts were done lately, with
the increase in available computational power, towards the
numerical modeling of these flows. Magnetic field seems to be a
key ingredient not only in jet formation, but also in
large-scale propagation, affecting the radiative emission
properties of the jet plasma. We will present the results of
such radiative MHD simulations, including a complex ionization
network and cooling function, and our approach to "synthetic
observations" of stellar jets.
- Owen Pavel Fernández
Piedra (Universidad de Cienfuegos, Cuatro Caminos,
Cienfuegos, Cuba)
- Title of Poster Contribution
(STARS2011): Vacuum Polarization Effects on Quasinormal
Modes
Owen Pavel Fernández Piedra and Jeferson de
Oliveira
Abstract: In
this work we studied the influence of vacuum polarization of
quantum massive fields on the quasinormal spectrum of
four-dimensional Reissner-Nordström black holes. First, we
consider a mixture of quantum massive fields interacting with
gravity near a black hole in order to calculate its quantum
stress-energy tensor using the Schwinger-De Witt expansion.
Having the expression the stress-energy tensor we solve
perturbatively the back reaction problem due to these quantum
fields upon the background space-time, obtaining a
semi-classical charged black hole solution that take into
account the gravitational vacuum polarization of the quantum
fields. As a next step we consider the evolution of a probe
classical massless scalar field in the background of the
semi-classical black hole, and determine, using a sixth order
WKB expansion of the effective potential, the quasi-normal
frequencies of the perturbation through the solutions of the
wave equation with the specific boundary conditions requiring
pure outgoing waves at spatial infinity and pure incoming waves
on the event horizon. As a remarkable result, we observed a
shift in the quasi-normal spectrum due to the vacuum
polarization of quantum fields in semiclassical
Reissner-Nordström black holes, more pronounced for the
fundamental mode. Through the calculation of the quality factor
of the oscillations, we conclude that the semi-classical black
hole is a better oscillator than their bare classical
partner.
- Title of Poster Contribution
(STARS2011): Spinor Perturbations in Four Dimensional
Stringy Black Holes
Owen Pavel Fernández Piedra and Jeferson de
Oliveira
Abstract: In
this work we study Weyl fermion perturbations in four
dimensional black holes of string theory, obtained either from
a non-extreme configuration of three intersecting five-branes
with a boost along the common string or from a non-extreme
intersecting system of two two-branes and two five-branes. We
obtain the Dirac equation for Weyl spinor field evolving near a
four-dimensional stringy black hole, and after conformal
re-scaling of the metric, we perform a numerical integration of
it to observe the time evolution of the fermion perturbation in
this particular spacetime. Specifying as boundary conditions
the presence of only pure outgoing waves at spatial infinity
and pure incoming waves on the event horizon, we compute the
complex frequencies that dominate quasi-normal ringing using
two methods: a numerical Prony fitting of the time domain data
and a semi-analytical sixth order WKB approach, and present an
analytical expression for the quasi-normal frequencies in the
limit of large angular momentum. We also perform a numerical
investigation of the relaxation of spinor perturbations in
stringy black holes at very long times, and show that the
falloff is identical to those appeared for massless fields
outside other four-dimensional black hole solutions in
classical general relativity.
- Title of Poster Contribution
(STARS2011): Object Picture, Quasinormal Modes and Long
Time Relaxation of Rarita-Schwinger Perturbations in Four
Dimensional Static Black Holes
Owen Pavel Fernández Piedra
Abstract: The
evolution of massless gravitino perturbations in four
dimensional static black holes is studied in detail. First, we
write the perturbation equations for Rarita-Schwinger fields in
a general background spacetime corresponding to a static
solution of Einstein fields equations without cosmological
constant. In the specific case of Schwarzschild and
Reissner-Nordström black holes, we perform a separation of
variables to leave the problem in a form suitable for numerical
integration of the evolution equations. Using a characteristic
integration scheme, we obtain the profiles that describe the
evolution of gravitino perturbations outside static black
holes, and concludes that this evolution involves the usual
three stages developed by fields of other spin: a transient
epoch strongly dependent on the initial conditions, a
quasi-normal ringing state for intermediate times and a very
long time power law fall-off. We determine the quasi-normal
frequencies numerically using an adequate fitting method of the
data profile, and also using a semi-analytical sixth order WKB
approximation. We also make similar calculations to determine
the response of a static black hole for boson and Dirac
perturbing fields and show that the quality factor becomes a
decreasing function of the spin for boson perturbations,
whereas the opposite situation appears for fermion ones. With
respect to the late-time behaviour, we found numerical evidence
of a faster decay of gravitino perturbations, a result in
constrast to that known for the other neutral fields.
- Title of Poster Contribution
(STARS2011): The Evolution
of Dirac fields in the Horowitz-Maldacena-Strominger Black Hole
with U(1) Charges
Owen Pavel Fernández
Piedra, Yulier Jiménez Santana and Fidel Sosa
Abstract: The
aim of this report is to discuss results concerning the study
of weak Weyl fermion waves propagating outside five dimensional
black hole solutions with U(1) charges constructed from
string-brane theory. We solve the Dirac equation for spin 1/2
fields in general d-dimensional spherically symmetric
spacetimes, and uses this results to determine numerically the
complete time evolution of this massless perturbations in the
given metric. Quasi-normal ringing followed by long time tails
are clearly observed for all values of charges, and constitutes
a good evidence for the stability of this higher dimensional
compact objects under fermion perturbations. Specifying as
boundary conditions the presence of only pure outgoing waves at
spatial infinity and pure incoming waves on the event horizon,
we compute numerically and semi-analytically the quasi-normal
frequencies. We also present an analytical expression for the
quasi-normal frequencies in the large angular momentum limit
obtained using the first order WKB approximation that gives the
exact result in this case. The power law exponents that
describes the relaxation of the field at very long times are
numerically computed, showing that fermion and boson fields
decay identically in this particular gravitational
background.
- Title of Poster Contribution
(STARS2011):Scalar Field
Evolution in d-dimensional Black Holes from String
Theory
Elcio Abdalla, Owen Pavel Fernández Piedra and
Jeferson de Oliveira
- Peter O. Hess
(Universidad Nacional Autónoma de México (UNAM), Mexico)
- Title of Talk (STARS2011): Pseudo-Complex General
Relativity
Peter O. Hess and Walter Greiner
Abstract:
General Relativity is extended to the pseudo-complex
coordinates. We discuss the formulation of the theory and the
projection to real numbers. The case of a central massive body
(Schwarzschild) and of the Robertson-Walker universe. It is
shown that the pseudo-complex formulation introduces a dark
energy, which accumulates around massive bodies and finally
prevents the formation of a black hole. In the case of the
Robertson-Walker universe, the dark energy accelerates the
universe. Several new solutions are found.
- Title of Talk (to SMFNS2011): Solvable Models and
Hidden Symmetries in QCD
Peter O. Hess
Abstract: The
Hamiltonian of QCD at low energy is divided in a main and a
perturbative part. The main restriction is to a finite volume.
For the main part of the Hamiltonian analytic solutions can be
found, including up to three orbital levels. For an arbitrary
number of orbitals, two successive unitary transformations are
applied leading again to an analytic solution.
- Peter Schiffer (RWTH
Aachen Universitaet, Aachen, Germany)
- Title of Talk (SMFNS2011): Constraining Cosmic
Magnetic Fields Using the Pierre Auger Observatory
Peter Schiffer (for the Pierre Auger
Collaboration)
Abstract: Being
most likely charged particles, ultra high energy cosmic rays
(UHECRs) are deflected in cosmic magnetic fields and thus offer
the possibility for constraining these fields. As the
deflection strength depends on the energies of the UHECRs, an
energy ordering in the arrival directions of UHECRs is expected
for a wide range of source and magnetic field scenarios. The
Pierre Auger Observatory, as the world´s largest experiment for
the measurement of UHECRs, offers the opportunity for the
search of structure in their arrival directions. The results of
anisotropy searches at the Pierre Auger Observatory are
reviewed with a special emphasis on cosmic magnetic fields. In
addition to that novel methods for constraining these magnetic
fields are discussed and their prospect is explored by using
Monte Carlo models of cosmic magnetic fields and UHECR source
distribution.
- Remo Ruffini
(Università degli Studi di Roma "La Sapienza", Roma, Italy)
- Title of Talk (STARS2011): The Need of Critical
Fields in Neutron Stars and Black Holes from Gamma Ray
Bursts
Remo Ruffini
- Renxin Xu (Peking
University, Beijing, China)
- Title of Talk (STARS2011): Pulsars: Gigantic
Nuclei
Renxin Xu
Abstract:
Because of the strong coupling between quarks of cold matter in
realistic compact stars, quarks could be clustered together
there, even in a solid state. Although such kind of matter
would be similar to nuclear matter,we call it still as "quark"
matter since quark degree of freedom appears during the
formation and stars composed by this matter behavior like
conventional quark stars rather than normal neutron stars in
astrophysics. Arguments from a model in-dependent point of view
are presented, that realistic quark matter could be in a solid
state which could be necessary to understand different
manifestations of pulsar-like stars. One of the key differences
between fluid and solid quark stars is relevant to starquakes:
the former cannot have while the latter can.
- Title of Talk (SMFNS2011): Magnetars: fact or
fiction?
Renxin Xu
Abstract: It is
a hot topic that compact stars with extremely strong magnetic
fields,~ 10[14-16]G, so called "magnetars" would
exist in the Universe; however, we are questioning this
speculation from both theory and observation. The power source
of AXPs/SGRs is actually the magnetic energy through
field-reconnection in magnetar model, while we think that star
quake-induced elastic and gravitational energies could possibly
power the bursts of SGRs and AXPs in a solid compact star
model. An AIQ (accretion-induced star-quarke) model is
presented and discussed.
- Ricardo Gonzalez
Felipe (Instituto Superior de Engenharia de Lisboa (ISEL)
and Instituto Superior Técnico (IST), Lisboa, Portugal)
- Title of Talk (STARS2011): Neutrinos and the
Matter-antimatter Asymmetry in the Universe
Ricardo Gonzalez Felipe
- Riccardo Belvedere
(Università degli Studi di Roma "La Sapienza", Roma, Italy)
- Roberto A. Sussman (Universidad Nacional
Autónoma de México (UNAM), Mexico)
- Title of Talk (STARS2011): Non-spherical Voids: the
best available challenge to the dark energy paradigm
Roberto A. Sussman
- Rodrigo Picanço
Negreiros (Frankfurt Institute for Advanced Studies
(FIAS), Johann Wolfgang Goethe University, Frankfurt am Main,
Germany)
- Rolando Cardenas
Ortiz (Universidad Central de Las Villas, Santa Clara,
Cuba)
- Title of Talk (STARS2011): Effects of Galactic Gamma
Ray Bursts on Planetary Atmospheres and Biospheres
Osmel Martín, Rolando Cárdenas Ortiz, Jorge Horvath
and Liuba Peñate
Abstract: We
examine the effects that a galactic gamma ray burst would cause
on planetary atmospheres with and without ultraviolet
screeners. We assume a spectrum of the gamma ray burst coming
from a massive star and use a radiative transfer model in the
atmospheres considering mainly photo-absorption and Compton
scattering. Then we focus on the re-emission of aurora like
spectra due to the action of secondary electrons and finally
estimate the distances at which highly evolved massive stars
can be dangerous for planetary atmospheres and biospheres.
- Rosana de Oliveira
Gomes (Universidade Federal do Rio Grande do Sul (UFRGS),
Porto Alegre, Brazil)
- Ttile of Poster Contribution (STARS2011): Mass-Radius
Relation for Hybrid Stars Under Deconfinment Phase
Transition
Rosana de Oliveira Gomes, Moisés Razeira, Alexandre
Mesquita, Francisco Fernández and César Zen
Vasconcellos
- Sérgio
Szpigel (Universidade Presbiteriana Mackenzie, São Paulo,
Brazil)
- Title of Poster Contribution (STARS2011): Subtractive
Renormalization in Effective Field Theories for Nuclear
Forces
Sérgio Szpigel, Varese S. Timóteo and Francisco de
O. Durães
Abstract: The
standard procedure for the renormalization of nucleon-nucleon
(NN) interactions in the context of Weinberg’s approach
to chiral effective field theory (ChEFT) consists of two steps.
The first step is to solve the Lippmann-Schwinger (LS) equation
for the scattering amplitude with an effective NN potential
which consists of pion-exchange interactions and contact
interaction terms. This requires the use of a regularization
scheme in order to overcome the ultraviolet divergences
generated in the momentum integrals when the NN potential is
iterated. The second step is to determine the strengths of the
contact interactions, the so called low-energy constants
(LEC's), by fitting a set of low-energy scattering data. Once
the LEC´s are fixed for a given regularization scale, the LS
equation can be solved to evaluate other observables. The most
common scheme used to regularize the LS equation is to
introduce a cutoff regularizing function that suppresses the
contributions from the potential matrix elements for momenta
larger than a given cutoff scale, thus eliminating the
ultraviolet divergences in the momentum integrals. An
alternative approach is the subtractive renormalization or
subtracted kernel method (SKM) in which, instead of using a
cutoff function, the LS equation is regularized by performing
subtractions in the kernel at a given energy scale. An
advantage of the SKM approach is that it can be extended to any
derivative order of the contact interactions through a
recursive process involving multiple subtractions. In this work
we study the subtractive renormalization of NN interactions
both in pionless EFT and in ChEFT up to next-to-next-to-leading
order (NNLO). We apply the SKM approach to describe the NN
scattering in the 1S0 partial-wave channel and show by explicit
numerical calculations that the procedure is fully
renormalization group invariant with respect to the change of
the subtraction scale through a non-relativistic
Callan-Symanzik equation.
- Title of Talk (SMFNS2011): Similarity Renormalization
Group Evolution of Nuclear Forces
Sérgio Szpigel, Varese S. Timóteo and Francisco de
O. Durães
Abstract: The
Similarity Renormalization Group (SRG) is a method based on a
series of continuous unitary transformations that evolve
hamiltonians with a cutoff on energy differences. Viewing the
hamiltonian as a matrix in a given basis, the SRG
transformations suppress off-diagonal matrix elements as the
cutoff is lowered, driving the Hamiltonian towards a
band-diagonal form. Recently, the SRG has been used as a tool
to evolve both phenomenological and chiral effective field
theory (ChEFT) nucleon-nucleon (NN) potentials to phase-shift
equivalent softer forms, effectively decoupling low-energy
observables from high-energy degrees of freedom. It has been
shown that such a decoupling leads to more perturbative NN
potentials, improving convergence and simplifying calculations
in nuclear few- and many-body problems. An alternative
renormalization group method that has been applied in this
context is the Vlow-k approach, in which the hamiltonians are
evolved with a cutoff on momenta. In this work we study the SRG
evolution of ChEFT NN interactions at leading order (LO)
derived within the framework of the Subtracted Kernel Method
(SKM), a renormalization scheme based on a subtracted
scattering equation. We apply the SRG transformation to evolve
the SKM-LO ChEFT potential in the 1S0 and the 3S1-3D1
partial-wave channels and analyze the decoupling pattern
between low- and high-momentum components. The results are
compared with those obtained for other NN potentials, such as
the Nijmegen II, the Argonne V18 and the chiral N3LO potential
of Entem and Machleidt.
- Stefan Schramm
(Frankfurt Institute for Advanced Studies (FIAS), Johann Wolfgang
Goethe University, Frankfurt am Main, Germany)
- Title of Talk (STARS2011): Dense Matter and Neutron
Stars in Parity-Doublet Formulations of Chiral
Symmetry
Stefan Schramm
Abstract: There
are various formulations of chirally symmetric systems of
hadrons. In this talk I will discuss the so-called
parity-doublet formulation, where in addition to the nucleon
its corresponding state with opposite parity is included. One
advantage of this approach is the possibility of defining a
chirally symmetric effective mass term in the Lagrangian. In
this formulation the signal for chiral symmetry breaking is the
onset of mass degeneracy of the parity partners. I will show
results for dense isospin-symmetric hadronic matter and the
possibility of first-order chiral phase transitions or a smooth
cross-over depending on parameters. In addition I will discuss
neutron star matter in beta equilibrium and the resulting
properties of neutron stars. In an extension of this
calculation I will present a SU(3) formulation of the parity
doublet model, its phase structure as well as the resulting
neutron star properties.
- Title of Talk (SMFNS2011): Nuclear Matter, Nuclei and
Neutron Stars in a Quark-Hadron Model
Stefan Schramm
Abstract: One
of the difficulties in describing chiral symmetry and
deconfinement phase transitions in strongly interacting matter
at high temperatures as well as at high densities stems from
the fact that one has to deal with very different degrees of
freedom at both sides of the phase transition, i.e. hadrons at
low temperatures/densities and quarks and gluons in the other
extreme. Glueing two separate equations of state together will
necessarily lead to first-order phase transitions (which are
not expected, at least not at small densities and high
temperatures). In order to remedy this problem a unified model
of quarks and hadrons (the QH model) has been developed that
integrates both degrees of freedom in an effective chiral
flavor-SU(3) ansatz. I will show results for nuclear matter,
nuclei and neutron stars, including effects of strong magnetic
fields, for the purely hadronic part of the theory and then
results for excited matter and stars for the full QH model.
Various extensions of this approach will be discussed.
- Thomas Boller
(Max-Planck-Institut fuer extraterrestrische Physik, Garching,
Germany)
- Title of Talk (STARS2011): Precision Measurements in
the Galactic Center
Thomas Boller
Abstract: The
Galactic Center (GC) is a uniquely accessible laboratory for
exploring a broad range of scientific questions related to the
interaction of a massive black hole (MBH) with its environment.
I highlight two central aspects: The stellar orbits and the
flares from the MBH. Stellar orbits show that the gravitational
potential to a scale of a few light hours is dominated by a
concentrated mass associated with the compact radio source Sgr
A*. I discuss the strong observational facts that Sgr A* is a
MBH but also still alternative explanations. Once per day Sgr
A* exhibits infrared flares during which its flux increases by
a factor 10-50. Flares are probably due to synchrotron emission
of transiently heated electrons in the innermost accretion
zone.
- Title of Talk (SMFNS2011): Probing the Strong and
Weak Field Limit in Active Galaxies
with Soft X-rays
Thomas Boller
Abstract:
Strong X-ray reflection is a natural consequence for the
existence of a compact corona close to the central black hole
disc system in active galaxies. Recently we (Boller, Mueller
2010) showed that a very close reflector is described by high
emissivity indices of about 6, inner disc radii of about 3 RG,
resulting into black hole spins of about 0.8, high
metallicities and strong Compton broadening effects. The FWHM
values of the emission of many unresolved lines centred at line
blends at around 0.33 and 0.6 keV are of the order of c/3. The
very nearby reflector probes the strong field limit in active
galaxies. Furthermore, an acceptable data fit requires
additional less broadened soft X-ray lines which are farther
away from the black hole and which probe the weaker field
limit. The current generation of X-ray observatories,
particularly Chandra and XMM-Newton, have provided new insights
into the astrophysics and the demographics matter under strong
gravity. I will review this progress, and look forward to how
this work may be taken forward in the future with eROSITA, the
International X-ray Observatory (IXO), and a new X-ray
observatory concept, GRAVITAS.
- Walter Greiner
(Frankfurt Institute for Advanced Studies (FIAS), Johann Wolfgang
Goethe University, Frankfurt am Main, Germany)
- Title of Talk (STARS2011): Extension of the Periodic
System: Superneutronic, Superheavy, Superstrange
Elements
Walter Greiner
Abstract: The
extension of the periodic system into various new areas is
investigated. Experiments for the synthesis of super-heavy
elements and the predictions of magic numbers are reviewed.
Different ways of nuclear decay are discussed like cluster
radioactivity, cold fission and cold multi-fragmentation. Up to
now super-heavy nuclei were only produced close to the proton
drip line. The recent Dubna experiments utilizing a
48Ca beam have been confirmed at an essential
intermediate decay at GSI. Thus we can state that super-heavy
nuclei up to Z = 118 have been found. In order to make
super-heavies closer to the stable valley by increasing the
neutron number we investigate the bombardment of e.g. U+Cm and
its decay down to the super-heavy island around Z = 114 and
120. In this connection also the time delay in the formation of
the giant nuclear system U+Cm up to 10-19 sec is
found. This is most important for studying the decay of the
super-critical electron-positron vacuum. A trigger for such
giant nuclear systems with long delay times (~
10-19s) is e.g. large mass transfer, e.g. U+Cm
→Pb+rest. In this connection the basics of the decay of
the vacuum in super-critical Coulomb fields is reminded. A very
important, novel idea came up a number of years ago in work
with K. Gridnev, D. Gridnev, V. Tarasov and St. Schramm. We
suggested that extremely neutron rich nuclei might exist, i.e.
nuclei like 42O, 42Mg, 42Al,
260Pb, etc. Meanwhile we extended this investigation
along the neutron drip line and found extended riches and
islands of extreme neutron nuclei. This opens the door to an
extremely wide and new field of research, which is very
important in nuclear astrophysics. Long living super-heavy
nuclei with sufficiently large neutron number can be produced
in macroscopic quantities by double-atomic-bomb explosions in
deep underground or by pulsed reactors with sufficiently high
neutron flux. A perspective for future research is given. This
includes also a theoretical study of super-heavy element (SHE)
formation by supernova explosions and thus the possible
occurrence of SHE in nature. Furthermore, investigations on
hyper-nuclei and the possible production of antimatter-clusters
in heavy-ion collisions are reported. Various versions of the
meson field theory serve as effective field theories as the
basis of modern nuclear structure and suggest structure in the
vacuum which might be important for the production of hyper-
and antimatter. I also discuss the possibility of producing a
new kind of nuclear systems by putting a few antibaryons inside
ordinary nuclei. This leads to surprising results: in
particular to cold compression of nuclear matter- in contrast
to hot compression via nuclear shock waves.
- Xiaoyu Lai (Peking
University, Beijing, China)
- Title of Talk (STARS2011): Quark Matter in the Early
Universe
Xiaoyu Lai
Abstract:
Strange quark nuggets (SQNs) could be the relics of the
cosmological QCD phase transition, and they could very likely
be the candidate of cold quark matter if survived the cooling
of the later Universe, although the formation and evolution of
these SQNs depend on the physical state of the hot QGP
(quark-gluon plasma) phase and the state of cold quark matter.
We reconsider the possibility of SQNs as cold dark matter, and
find that the formation of black holes in primordial halos
could be significantly different from the standard scenario.
The SQNs could lead to the formation of black holes with mass
as high as 103 Msun, which could be the
seeds for the supermassive black holes at redshift z ~ 6.
- Ttile of Talk (SMFNS2011): Primordial Strange Quark
Matter: creation and consequences
Xiaoyu Lai
- Abstract:
Cosmological QCD phase transition could have abundant
consequences on astrophysics. If it is of first-order, strange
quark nuggets could form. They could very likely be the
candidate of cold quark matter if survived the cooling of the
later Universe, although the formation and evolution of these
SQNs depend on the physical state of the hot QGP (quark-gluon
plasma) and the state of cold quark matter. We revisit the
possibility of SQNs as cold dark matter and study the possible
consequences. The assembling of SQNs in the center of
primordial halos could make it easier to form the supermassive
black holes at redshift as high as 6, and the SQNs diffused in
the present galaxy could trigger star-quakes of pulsars which
result in pulsar-glitches.
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