September 30 to October 03
Geometric Aspects of Venus Transit Alberto Carlos Bertuola IFSP
We obtain the values of the Venus` diameter and the distance Venus-Earth through a geometric study of the picture of the Venus´ transit ocorred in June of the year of 2012. A image treatment of the transit photos was done and two geometrical parameters were defined which numerical values were used in the geometrical model for the triangulation that takes in account Venus translation, Earth translation and Earth rotation. The results were satisfactory and they will be presented as medium and estimated values.
Galaxy morphology in large surveys: quality assessment of SExtractor and PSFex Aldée Charbonnier Centro Brasileiro de Pesquisas Físicas
The determination of structural parameters of galaxies provides key information for studies of galaxy evolution and leads to robust photometrical and mophometrical measures that may be useful for photometric redshits and weak lensing, among other applications. The upcoming wide-field surveys will provide an unprecedented number of objects for which their morphology can be determined, enabling several statistical studies. However, fast tools to carry out the automated analysis of these objects, at the same time accounting for the point spread function (PSF) across the observed field are required. The SExtractor software (Bertin & Arnouts, 1996) is widely used in the community for the production of detection catalogs. Its functionality has been recently extended to the characterization of the morphology of objects. It allows to fit a set of brightness profiles automatically for each object on the images (de Vaucouleurs, exponential, more generally the Sersic profile, and a combination thereof). The PSF of the images may be estimated via the PSFex software, also developed by E. Bertin. These two codes have several advantages: they are compatible in terms of data format (i.e. they can be directly concatenated) and their speed allows for their practical use in large surveys. We have used and tested them on a recent survey conducted with CFHT (the CFHT/MegaCam Stripe-82 Survey - CS82), consisting of ~170 square degrees observed in the i-band down to mag ~ 24, with median seeing of ~0.65" in the so called SDSS "Stripe-82" equatorial region. The results of the structural parameters for various profiles for around 16.10^6 objects in this survey will be presented by M. E. Pereira. The performance of the two codes combined has also been assessed on the COSMOS field observed by the ACS camera on the Hubble Telescope and by CFHT MegaCam (comprising the CFHTLS Deep 2 field - D2), which will be the subject of this presentation. The combined tests on the deep D2 field and the wide CS82 survey provide a good indicative of what may be achieved with the next generation wide-field surveys from the ground such as DES or LSST and pave the way for the exploitation of structural parameters in these surveys. The SExtractor and PSFex suite appear to be up to the task in providing reliable structural parameters for the galaxies in these surveys with a manageable computational time.
Light Dark Matter Production Alexander Lunkes dos Santos UFRGS
We investigate a production of light dark matter in a double extension of Standard Model (SM). This extension is made adding two extra gauge group symmetry $U(1)$ to the Standard Model, one via Stueckelberg mechanism and another via minimal coupling. The Stueckelberg mechanism is one of the ways to give mass to the particles. So we get two new gauge bosons, one called $Z $ which is massive and the other $gamma$ or dark photon, which is massless and doesn t interact with the standard model particles. Therefore we can calculate the creation process of dark particles $e^- e^+ ightarrow ar{chi} chi $, where $chi$ is a dark fermion and the process is mediated by three bosons: $gamma, Z, Z $. Some results and perspectives are presented.
From “Ultrahigh to Extreme” Energy cosmic rays Angela Olinto Univ. of Chicago
The origin of cosmic rays is still a great mystery. A century of observations have given us great insight into the properties of the cosmic ray flux and composition on Earth, but strong anisotropies are still elusive. The lower energy Galactic sources are beginning to be identified by gamma-ray observations and careful simulations of cosmic ray acceleration and propagation. The first observations of high-energy neutrinos were recently announcement and they may be due to intermediate energy cosmic ray propagation or sources. At the highest energies, sources should be among the most powerful extragalactic objects. Great progress over the last decade has confirmed the expected behavior of the spectrum but has found surprises by the lack of strong anisotropies and a possible change of composition. Not a single source of these extremely energetic events has been identified. Next generation detectors will be capable of detecting a large number of extreme energy cosmic rays that can finally lead to a identification of the mysterious extreme accelerators. In Lecture 1: I will review the basics of cosmic ray observations and the ingredients of models used to explain them.
Systematic neutrino nucleus cross sections in GTBD Arturo Samana UESC
In this work we performed a systematic study of the inclusive neutrino cross sections for 1498 nuclei with 6 < A <210. The set of nuclei were selected to have ft-values corresponding essentially to allowed and first forbidden beta decay rates. As in Ref. [1], the nuclear gross theory, originally formulated by Takahashi and Yamada [2] for the beta-decay, is applied to the electronic-neutrino nucleus reactions, employing a more realistic description of the energetics of the Gamow Teller resonances. The model parameters were gauged from the most recent experimental data, both for beta-decay and electron capture, separately for even-even, even-odd, odd-odd and odd-even nuclei. An extension to nuclei with A > 70 is implemented improving the previous calculation with A < 70 [1]. A numerical fitting of the cross sections as function of incident neutrino energy E_ u, atomic number Z and mass number A is performed to have in view astrophysical applications as such as the r-process nucleosynthesis. References. References [1] A. R. Samana, C. A. Barbero, S. B. Duarte, A. J. Dimarco e F Krmpoti¶c, New Journal of Physics 10, 033007 (2008). [2] K. Takahashi e M. Yamada, Prog. Theor. Phys. 41,1470 (1969).
On the effect of the Anomalous-Magnetic-Moment in the EoS of the Magnetized Dense System Aurora Perez Martinez ICMF
Quantum corrections of the anomalous magnetic moment (AMM) for fermions in the presence of a strong magnetic field using the Ritus`s approach are investigated. At strong fields the particles get different AMM`s depending on the LL`s. At weak field the AMM is independent of the LL (Schwinger approximation for AMM). The significance of the AMM contribution to the Equation of State (EoS) of the magnetized system, in the weak and strong field approximations is studied.
Effective mass, nuclear matter incompressibility, symmetry energy and slope correlations. Bianca Martins Santos Universidade Federal Fluminense
In this work we show how the effective mass of relativistic mean-field (RMF) models can reveal correlations with the nuclear matter incompressibility. We have verified a linear dependence of the incompressibility ($K$) as a function of the skewness parameter at the saturation density for fixed values of the effective mass. The results confirm the findings of Khan and Margueron~[1]. The same result is found when the dependence of $K$ as a function of its first derivative is analyzed. Such a quantity is strongly related to the experimental data of the centroid energy of the giant monopole resonance. In order to have analytical expressions in our study, we consider the Point-Coupling version of the usual RMF models added with the approximation of equal scalar and vector densities in the models. Such an approximation is very robust when the densities ($ ho$) are lower than the nuclear matter saturation density ($ ho_{o}$). In the same regime we discuss the crossing density ($ ho_{c}$) for different effective masses. The results are very promising to further investigations about correlations among nuclear matter observables at a low density regime where expansions for incompressibility, symmetry energy and its slope are important. oindent [1] E. Khan and J. Margueron, arXiv:1304.4721v1 [nucl-th].
Decay of the magnetic field in "black widow" pulsars Camile Mendes Castilho IAG - Universidade de São Paulo
A small fraction of the binary relativistic systems display the “black widow” effect: the companion is being ablated by the (recycled) pulsar wind. In these binary systems the evolution of the companion star (of the solar-type) reaches the point of filling its Roche lobe, thus initiating the process of mass accretion onto the pulsar. Accretion is generally believed to result in magnetic field decay [1], while isolated neutron star fields decay very slowly , if at all [2]. We shall show that the very long evolution of the “black widow” system, starting from a solar-type star and lasting > 5 Gyr to reach the observed position in the P_orb-M_donor plane, allows us to conclude that the magnetic field does not decay below the “bottom” value 〖~2×10〗^8 G, extending the previous conclusions drawn from younger systems. In addition, the masses of the “black widow” pulsars are naturally predicted to be > 2 Mo due to the accretion history, in full agreement with recent measurements [3,4] 1]N. Shibazaki, T. Murakami, J. Shaham, K. Nomoto, Nature 342, 656 (1989) 2] C. M. Zhang, Proceedings IAU Symposium, 291 (2013) 3] M. van Kerkwijk, R.P. Breton and S.R. Kulkarni, ApJ 728, 95 (2011) 4] R. Romani et al., ApJ 760, L36 (2012)
STUDY OF SIX MECHANICAL TWO-MODE IMPEDANCE MATCHERS IN SCHENBERG DETECTOR USING FEM Carlos Frajuca Sao Paulo Federal Institute
A spherical gravitational wave (GW) detector has a heavy ball-shaped mass which vibrates when a GW passes through it. Such motion is monitored by transducers and its respective electronic signal is digitally analyzed. One of such detectors is Mario Schenberg Detector - that will have resonant frequencies around 3.2 kHz making the transducer development for this higher frequency detector somewhat more complex. In this work we present a series of finite study elements of a sphere coupled to two-mode mechanical oscillators that will work as mechanical impedance matchers between the sphere and the microwave transducer. We describe the search for a shape of the impedance matcher that might improve the performance of the detector. We found that the normal modes of the coupled system are not exactly degenerative, although theoretical calculation predicts that they should be. This work also reports improvements made in the modelling of mechanical impedance matchers using finite elements method when shell elements type were used instead of tetrahedron elements type, showing that this method works as a very reliable approximation, confirmed by the approximated symmetries restoration in the frequency mode peaks.
Linearised regime of the Einstein s field equations in the characteristic outgoing formulation of general relativity Carlos Eduardo Cedeño Montaña INPE
We present the Einstein s field equations in the characteristic outgoing formulation of general relativity in the linearised regime. As a test of validity of the equations we found, from the News function, the power emitted in gravitational waves by a binary system of two equal masses in eccentric orbit. Also, we show that this result is in agreement with the conventional approach
Casimir effect in Lense-Thirring-DeSitter spacetime Celio Muniz Univ. Estadual do Ceará e Univ.Federal da Paraíb
We calculate the renormalized vacuum energy of a massless scalar field confined between two nearby parallel plates formed by ideal discharged conductors, placed at the equatorial region of and tangentially to a rotating sphere with mass $M$ and radius $R$, in both low rotation and weak field approximations of the Kerr metric (i.e., Lense-Thirring one) with the presence of a cosmological constant. Corrections to the Casimir energy of the cavity formed by the plates in Minkowski spacetime are obtained in first order of approximation of $M/R$. The found results, unlike the case in which the massive sphere is in rest, even in first order approximation already exhibit an important modification in Casimir energy, which depends on surface gravity combined with spacetime rotation and non-inertial effects, as well as on cosmological constant. Is shown that such additional effects attenuate the Casimir force between the plates.
Implications of PSR J1614-2230 for NJL hybrid star Cesar Lenzi UTFPR
The recent determination of the mass of the pulsar PSR J1614-2230 with 1.97 solar mass, renewed the discussions about the possibility of exotic matter being present at the core of neutron stars. Since the description of matter at densities beyond nuclear saturation is model dependent, several works have explored different aspects of the fact that the maximum neutron star mass implied by any equation of state must exceed the mass of PSR J1614-2230. In this work we present an extensive study of hybrid star masses using several parametrizations of a relativistic mean-field hadronic EoS together with a typical three-flavor NJL model with scalar, vector and t Hooft interactions as realized.
A Relativistic Effective Field Theory (EFT for Nuclear Matter With Many-Body Forces Cezar Augusto Zen Vasconcellos UFRGS
Nuclear science has developed many excellent descriptions that embody various properties of the nucleus, and nuclear matter at low, medium and high densities. However, a full microscopic understanding of nuclear systems is still lacking. The aim of our research is to shed some light on such challenges and particularly on open questions facing the high density nuclear many-body problem. Here we focus our attention on the conceptual issues of analyticity, unitarity, causality, cluster decomposition, symmetries of the strong interaction (Lorentz invariance, parity conservation, isospin, and spontaneously broken chiral symmetry) and naturalness and their role in shaping the baryon-meson phase space dynamics in the description of the equation of state (EoS) of nuclear matter. In particular, in order to stimulate possible new directions of research, we discuss relevant aspects of a recently developed relativistic effective theory for nuclear matter with parametric couplings and genuine many-body forces. Among other topics we discuss in this work the connection of this theory with other known effective QHD models of the literature and its potentiality in describing a new physics for dense matter
Automated detection of gravitational arcs in wide field surveys: the Mediatrix Arcfinder and comparison to other methods Clecio Roque De Bom Brazilian Center for Research in Physics
Gravitational arcs are powerful tools to study the matter distribution in galaxies and clusters. They are also useful probes to constrain cosmological parameters. A critical step in the gravitational arcs program it is the identification of arc systems. At present, of order of 102 arcs systems have been discovered in homogeneous samples. This number is expected to increase by an order of magnitude in the next few years due to the upcoming wide fields surveys that will cover several thousands square-degrees, such as the Dark Energy Survey (DES). Finding arcs in such large areas requires automated algorithms to select arc candidates among hundreds of millions of galaxies and other objects. In this contribution we present a new automated arcfinding method that uses a combination of novel methods to measure objects in images and a neural network to select arc candidates, named MediatrixArcfinder. Objects are identified by SExtractor (Bertin & Arnouts 1996) and have their morphological properties derived from the Mediatrix decomposition (Bom et al. 2013) and derived parameters, which are used as input for the neural network. We also present a systematic comparison between this method and three other arcfinders available in the literature: Lenzen et al. (2004), Horesh et al. (2005), More et al. (2012). We determine the efficiency of these arcfinders as a function of arc properties for a sample containing thousands of simulated arcs. We attempt to understand the false positive population using simulated images for DES.
The Figure of the Sun from Ground-based Experiments Constantino Sigismondi ICRA Itália
The figure of the Sun has been investigated to assess the quadrupole moment of the Sun and its influence on the Mercury s perihelion precession. It has been carefully studied observationally from R.H.Dicke and collaborators in Princeton in a framework of possible modified theories of General Relativity since the late 60s. J.P.Rozelot and collaborators continued the studies at Pic du Midi Observatory aiming to uncover the internal structure of the Sun. Nowadays the interest of these studies covers also space and Earth climate issues, with the micro-variations of the solar diameter related to corresponding variations of the irradiance, and to coronal mass ejections. The Heliometer operating at the Observatorio Nacional in Rio de Janeiro has been conceived to obtain the measurement of the solar diameter at all heliolatitudes with an accuracy of one part over 100000. The first results (2010-2013) are discussed along with the data from the solar Astrolabe which observed from Rio during the period 1998-2009, covering a whole solar cycle. Finally the diameters coming from the observations of the transits of Venus in 2012 (China) and 2004 (Athens) are presented.
General Relativistic Anisotropic Hydrostatic Equilibrium Equations for a Magnetized Compact Object Daryel Manreza Paret Universidad de La Habana
We discuss the static solution of Einstein´s equations with cylindrical symmetry which could be a more suitable space-time symmetry for a magnetized compact object. The existence of high values of magnetic fields inside compact objects breaks the spherical symmetry and produce an anisotropy in the pressures inside the object. Einstein´s equations with cylindrical symmetry and an anisotropic energy-momentum tensor as a source are numerically solved to find Mass-Radius relations of compact objects.
Large scale renormalization group effects in gravity and their contribution to the kinematics and lensing of galaxies Davi Rodrigues UFES
The renormalization group framework can be applied to Quantum Field Theory on curved space-time, but (contrary to QED, for instance) there is no proof whether the beta-function of the gravitational coupling indeed goes to zero in the far infrared (large scales) or not. In accordance with the covariance of the Effective Action, we consider the possibility that this running may lead to observational effects at astrophysical distances, and evaluate the kinematics of diverse types galaxies (dwarf, giant, disk or elliptical) and lensing effects. If such effects are indeed real, we find that the amount of dark matter in galaxies may be significantly lower than usually estimated. Based on D.C. Rodrigues, JCAP 2012; D.C. Rodrigues, I.L. Shapiro, P. Letelier, JCAP 2010; and works in progress in collaboration with J. Fabris, B. Koch, O. Piattella, P. de Oliveira and I. Shapiro.
ESTIMATING THE SLOPE OF AVERAGE ROTATIONAL AXES STARS IN OPEN CLUSTER PLEIADES DAYVID MIRANDA UERN
The true rotational velocity of star, $ V $, can be measured from the radius and period of the star. However, determination of the angle of inclination of the rotational axis with the sight line i, is possible only in special cases (eg, star or measured rotation period in binary systems with rotation and translation synchronized). Often, the average equatorial speed, $langle V angle$, for a sample of stars is usually estimated by the ratio between the projected average speed, $langle V sin i angle$, and the sine of the angle of inclination, $langle sin i angle$. The latter is assumed to always equal to $pi/4=0,79$ chance of random distribution of rotational axes irrespective of the particular stellar population or sample. While this procedure has rarely led to discrepancies between theoretical models and the data observations. This work uses the radius star and the period of rotation to determine the equatorial velocity actual best fit with the curve of distribution of velocities equatorial actual procedure by which to determine the index q Tsallis entropy which allows to estimate the average $langle sin i angle$ based on a sample of radius, rotation periods and projected. This method is used to estimate the average $langle sin i angle$ of a database containing 217 stars in the Pleiades open cluster, whose rotation periods are available. The result shows an excellent agreement with the observational data.
Stochastic Background of Gravitational Waves Generated by Compact Binaries in Eccentric Orbits Edgard Freitas Diniz Evangelista INPE
It is well known that binary systems lose energy and momentum via emission of gravitational waves. Particularly, short-period systems formed by compact objects are among the most probable sources to have their signals detected in the near future by the interferometric detectors, such as the Advanced LIGO and the Einstein Telescope. Here, we are concerned with systems in eccentric orbits, which emit gravitational waves in a particular pattern: the radiation is split in harmonics, where the fundamental one is the quadrupole term, whose frequency is twice the orbital frequency. Our aim here is to obtain the stochastic background of gravitational waves generated by the population of cosmological compact binaries in eccentric orbits at the periodic and quasi-periodic phases.
Pion and kaon elastic form factors in the light-front model Edson Otoniel Instituto Tecnológico da Aeronáutica
In this work we calculated in an otimized way the electromagnetic form factors, of the pion and kaon mesons, by using the nonsymmetrical vertex model (NSVM) in the light-front formalism. The range of energy values used to describe the available experimental data at lower energy. By varying and analyzing the best value of NSVM parameters, we were able to verify the validity of the model and obtain an otimization of the numerical results for the radius of the pion and kaon, the decay constant and for the electromagnetic form factor. We show that such models can describe the experimental data at low energies very well. Varying the regulator mass of the model, we also showed the limits of application of the model utilized here
Effects of neutrino emissivity on the cooling of neutron stars in the present of a strong magnetic field Eduardo Lenho Coelho Universidade do Estado do Rio de Janeiro (UERJ)
Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. It is believed to be the process responsible for the cooling of young neutron stars after the first 100 years of life. One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars, with fields up to 10^14 G at the surface. It is natural then to inquiry about the modifications in the cooling due to Urca process in pulsars. In this work we investigate the influence of strong magnetic fields on the cooling of pulsars due to the neutrino emissivity coming from direct Urca process. The matter is described using a relativistic mean-field model at zero temperature. We calculate numerically the emissivity of neutrinos for different magnetic fields as a function of the baryon density and compare the results for the case without a magnetic field.
Resonant circuit to control pulsed ion beams Eduardo Guy Perpétuo Bock Sao Paulo Federal Institute
A resonant circuit is being studied in Federal Institute of Technology in Sao Paulo in partnership with Particle Linear Accelerator (LINAC) at the Institute of Physics in University of Sao Paulo . This work presents design, simulation and construction of an electronic controller of pulsed ion beams. Obtaining the sinusoidal electrical signal to control phase is a primary step in order to control pulsed ion beams in LINAC. The mathematical behavior of a phase modulator was studied and modeled using computational numerical simulation. Simulations were conducted in Mathematica (Mathematica, Wolfram Research, Champaign, Illinois) to determine parameters of control. The electronic circuit was designed based on those parameters to control the sinusoidal signal with phase quadrature modulation (I/Q). The proposed controller was assembled with splitter/combiner and mixers (MiniCircuits, Brooklyn, New York). The simulated adaptation was implemented in order to change the operating region (phase difference) circuit. The adaptations made it more suited to the purposes of the signal controlling carried by the modulator. The results point to a circuit with consistent response. The strategy adopted in the simulations and the modulator was considered satisfactory. As future works, we intend to improve the control applied in electronic circuit phase modulator and evaluate its operation "in loco" to control pulsed ion beams.
Ignition Mass for Supernova Explosion with an Effective Lagrangian Description Elvis Soares IF-UFRJ
We used a semi-anaytical approach to for the problem of the dynamical evolution of the explosion of a supernova to study the ignition mass for its explosion. The relevant coordinates of the dynamical problem are chosen to be the radii of the mass shells that compose the supernova and describe the global aspects of the process. The equations of motion are obtained from this Lagrangian and then integrated numerically. In this study, the pre-supernova stars considered are white dwarfs composed by carbon and oxygen. We have studied the ignition mass as a function of the mass of the star around the Chandrasekhar limit. We have also examined the influence of several equations of state in the dynamics of the star.
The current development of the Schenberg gravitational wave antenna s transducers Elvis Camilo Ferreira INPE
The Brazilian gravitational wave detector Mario Schenberg is installed at Physics Institute of the University of São Paulo. It consists of a spherical antenna made of 1150 kg of an alloy of CuAl(6%). Detection could be registered if the resonant normal modes of the sphere oscillate due to the passage of a gravitational wave. In order to amplify and transduce the mechanical vibrations into electrical signals, a set of eight parametric transducers were designed and constructed. We present the current development of these transducers, the process of adjusting their microwave cavities to resonate at 9.6 GHz and other challenges concerning this commissioning phase.
Refining the deformation noise spectral density for the detector Schenberg using FEM Fabio S Bortoli São Paulo Federal Institute (IFSP)
Schenberg is a spherical resonant mass gravitational wave detector. Its center operation frequency is 3200 Hz. Transducers located on the surface of ressonant sphere according to an semididecahedral distribution, are used to monitor the amplitude of displacement. The development of mechanical impedance matchers that function as sensory mechanics of the transducers in the Mário Schenberg detector, consists in such a way in a challenge for its conception as confection, this, to a large extent, had to its so great reduced size. There are times we are developing and optimizing a format matcher. The objective of this study is to obtain the noise spectral density for detector Mario Schenberg using this matcher, through finite element modeling (FEM).
Exclusive vector meson photoproduction in pA collisions at the LHC Glauber Sampaio dos Santos Universidade Federal do Rio Grande do Sul
In this work we study the exclusive photoproduction of J/Ψ and Υ mesons in the ultrarelativistic proton-nucleus interactions at the LHC energies and analyze if these processes can be used to determine the QCD dynamics at high energies. Exclusive vector meson production is a useful process providing important information on the transition region between soft and hard QCD regime. It is expected that eletromagnetic interactions be dominant at ultrarelativistic heavy ion collisions at large impact parameter of interaction. These collisions are characterized by restricting in the impact parameter b, where the requirement can be done for b to be larger than the sum of the hadron and nuclear target radius. The gain in studying photon induced interactions is the high equivalent photon energies that is achieved at LHC kinematic range. The theoretical approach considered in the present work is the color dipole picture, describing the quasi-real photon interaction with the nucleus target. In such a scenario, the projectile has just enough energy to fluctuate into a quark-antiquark pair long before the scattering. Furthermore, these pairs with transverse separation r interacts with the target as color singlet dipole. We calculate the integrated cross section and rapidity distribution within the QCD color dipole approach, providing theoretical prediction for the recent proton-lead run at the LHC for the energy of 5 TeV. A comparison with the linear dynamics predictions is also presented. Our results indicate that the nonlinear dynamics can be proven in those reactions, which are well suited for studing saturation effects.
Hadron-Quark phase transition in high-mass neutron stars Gustavo Contrera IFLP-CONICET & FCAG-UNLP
The recent discovery of the two-solar mass neutron stars J1614-2230 ($1.97 pm 0.04 M_{odot}$) and J0348+0432 ($2.01 pm 0.04 M_{odot}$) allows to consider the possible existence of deconfined quarks in the cores of neutron stars. Based on a non-local extension of the SU(3) Nambu Jona-Lasinio model with vector interactions to describe the quark matter phase, and a non-linear Walecka model to represent the hadronic phase, a phase transition between these two phases can be constructed via the Gibbs conditions and imposing global electric charge neutrality condition. Depending on the strength of quark vector repulsion, we find that an extended region made of a mixed phase of quarks and hadrons may exist in high-mass neutron stars with masses up to $2.1-2.4 M_{odot}$. The radii of these objects are between 12 and 13 km, as expected for neutron stars.
A Systematic Study of the Singular Isothermal Elliptical Lens Models in the Strong Regime HABIB SALOMON DUMET MONTOYA CBPF
We present some recent progresses on gravitational lens models based on the Singular Isothermal Sphere (SIS), widely used to represent lenses at galactic mass scale. We derive analytic solutions for the Singular Isothermal Ellipsoid (SIE) and Singular Isothermal with Elliptic Potential (SIEP), including constant convergence and shear fields. These solutions include i) expressions for the lensing of finite elliptical sources giving rise to arcs, ii) iso-convergence contours, constant magnification curves and constant distortion curves (including critical curves), iii) the magnification cross section and iv) deformation cross section. The solutions presented here, can be used to speed up numerical codes in applications to arc statistics, for the inverse modelling of the mass distribution from arcs, and other lensing observables.
Black hole Scalar Field Interactions: Characteristic Evolution and Evidence of Nonextensivity Henrique P. de Oliveira Universidade do Estado do Rio de Janeiro
We have studied the interaction of a black hole with a cloud of massless scalar field in spherical symmetry. The field equations were written in the characteristic formulation and integrated numerically with an accurate spectral code. The final outcome will be another black hole with a greater mass than the original one and formed after that an amount of scalar field mass falls into the hole. In this interaction a fraction of the scalar field is always radiated away. By evaluating carefully the black hole masses for distinct initial scalar field amplitudes, we have found that the distribution relating these quantities is a $q$-Gaussian function, which is a typical distribution of the nonextensive statistics. We present some discussion concerning this distribution in connection with the nonextensive character of the black hole entropy.
The Klein-Gordon equation in the spacetime of Kerr-Newman Horácio Santana Vieira Universidade Federal da Paraíba
This work deals with the influence of the gravitational field produced by a charged and rotating black hole on quantum systems. More specifically, are considered scalar quantum particles, which are described by the Klein-Gordon equation. We obtain an exact solution of the Klein-Gordon equation in the spacetime of Kerr-Newman, which is given in terms of the confluent Heun functions. Also, we recover the results already know in the literature for the regions near of the event horizon and at infinity provided that certain restrictions to parameters of the confluent Heun functions are imposed.
Science at FAiR Horst Stoecker GSI
The status of the international facility for antiproton and ion research in europe is presented. Emphasis is given to the four scientific pillars of FAiR: - Atomic-, applied and plasma physics (APPA ), - Relativistic heavy ion physics at highest baryon densities (CBM+HADES), - Nuclear Astrophysics and -Structure (NUSTAR) and - Antiproton science (PANDA)
Kinetic theory of collisionless self-gravitating gases: Relativistic corrections in galactic dynamics Javier Ramos-Caro Universidade Federal de São Carlos
We study the kinetic theory of many-particle astrophysical systems imposing axial symmetry and extending our previous analysis in Phys. Rev. D 83, 123007 (2011). Starting from a Newtonian model describing a collisionless self-gravitating gas, we develop a framework to include systematically the first general relativistic corrections to the matter distribution and gravitational potentials for general stationary systems. Then, we use our method to obtain particular solutions for the case of the Morgan and Morgan disks. The models obtained are fully analytical and correspond to the post-Newtonian generalizations of classical ones. We explore some properties of the models in order to estimate the importance of post-Newtonian corrections and we find that, contrary to the expectations, the main modifications appear far from the galaxy cores. As a by-product of this investigation we derive the corrected version of the tensor virial theorem. For stationary systems we recover the same result as in the Newtonian theory. However, for time dependent backgrounds we find that there is an extra piece that contributes to the variation of the inertia tensor.
A different nature between the radio AXPs in comparison to the others SGRs/AXPs Jaziel Goulart Coelho ITA
SGRs/AXPs are assumed to be a class of neutron stars (NS) powered by magnetic energy and not by rotation, as normal radio pulsars. However, the recent discovery of radio-pulsed emission in four of this class of sources, where the spin-down rotational energy lost $dot{E}_{ m rot}$ is larger than the X-ray luminosity $L_X$ during the quiescent state - as in normal pulsars - opens the question of the nature of these radio AXPs in comparison to the others of this class. In this work, we show that the radio SGRs/AXPs obey a linear log-log relation between $L_X$ and $dot{E}_{ m rot}$, very similar to the one of normal X-ray pulsars, a correlation not seen for the others SGRs/AXPs. This result suggests a different nature between the radio AXPs comparing to the others SGRs/AXPs.
A full study of solar analogs and twins: chromospheric activity and magnetic field Jefferson da Costa UFRN
Since the 1960ies a large number of studies were developed with the goal to find stars very similar with the Sun, the called solar analogs and solar twins. The rigor to classify these objects was increasing on the last years as a result of the observational instrumentation development. On this context, our study proposes an analysis of a bona find sample composed by 118 solar analogs and twins selected through photometric criteria. We analyzed several stellar parameters like: Stellar magnetic field, chromospheric activity, coronal abundance, and angular momentum for this stellar group. Our results reveal the evolution of chromospheric activity, stellar magnetic field, coronal activity, and chemical abundances in the HR diagram, we also study the distribution of stellar angular momentum as a function of mass for our stars. From our results we can highlight the development of others conditions to classify the solar analogs and twins stars.
Measurements and theory of neutron star masses Jorge Horvath IAG-USP
I review the most recent determinations of neutron star masses, pointing out that very heavy objects have been suggested in at least three binary systems. The equation of state that supports these masses must be very stiff, although it is far from clear how so. We discuss the consistency of high masses with our own "black widow" system evolution calculations.
A New Design for Connecting Transducers in Schenberg Detector José Alves de Amorim Sao Paulo Federal Institute
A spherical gravitational wave (GW) detector has a heavy ball-shaped mass which vibrates when a GW passes through it. Such motion is monitored by transducers and the respective electronic signal is digitally analysed One of such detectors, SCHENBERG, will have resonant frequencies around 3.2 kHz with a bandwidth near 200 Hz weighting 1.15ton, built in the Department of Materials at the University of Sao Paulo. The sphere with 65cm in diameter will be made of a copper-aluminum alloy with 6% Al. In this work a new design for the connecting the microwave parametric transducers is proposed. This design has many capabilities that the present does not have, for instance the capability to change the size of the gap during operation and improving the vibration seismic isolation.
Domain Wall Model in the Galactic Bose-Einstein Condensate Halo José Cleriston Campos de Souza Universidade Federal do ABC
We assume that the galactic dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate, can present topological defects, namely domain walls, arising as the dark soliton solution for the Gross-Pitaevskii equation in a self-graviting potential. We investigate the influence that such substructures would have in the gravitational interactions within a galaxy. We find that, for the simple domain wall model proposed, the effects are too small to be identified, either by means of a local measurement of the gradient of the gravitational field or by analysing galaxy rotation curves. In the first case, the gradient of the gravitational field in the vicinity of the domain wall would be $10^{-31}; (m/s^2)/m$. In the second case, the ratio of the tangential velocity correction of a star due to the presence of the domain wall to the velocity in the spherical symmetric case would be $10^{-8}$.
A new method of calculating the stochastic background of gravitational waves generated by compact binaries Jose C N de Araujo INPE
In the study of gravitational waves, the stochastic background generated by compact binary systems are among the most important kind of signals. The reason of such importance is the high probability of detection by the interferometric detectors (such as Advanced LIGO and Einstein Telescope) in the near future. In this paper we are concerned with the stochastic background of gravitational waves generated by double neutron star systems (DNS) in circular orbits during their periodic and quasi--periodic phases. Our aim here is to describe a new method of calculating such spectra, which is based on an analogy with a problem of Statistical Mechanics. Besides, an important characteristic of our method is to consider the time evolution of the orbital parameters.
Deconfinement and chiral restoration in nonlocal SU(3) chiral quark models Juan Pablo Carlomagno IFLP - CONICET
We study the features of nonlocal SU(3) chiral quark models with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. In this context we analyze the characteristics of the deconfinement and chiral restoration transitions at finite temperature, introducing the couplings of fermions to the Polyakov loop. We analyze the results obtained for various thermodynamical quantities considering different Polyakov loop potentials and nonlocal form factors, in comparison with data obtained from lattice QCD calculations.
Calibration device for Schenberg Detector Kaue AP. M. Santos Sao Paulo Federal Institute
Since the creation of the theory of relativity by Einstein in 1916, believes in the existence of gravitational waves. To make the direct detection in recent years have been developed several detectors around the world, but none of them achieved a positive result yet. One of these detectors is the Brazilian project called Schenberg detector. In this work a device for helping calibrate Schenberg detector is propose. It consists of two masses rotating at a frequency that excites the quadruple modes of the gravitational wave detector Mario Schenberg. The big challenge is to get the two masses rotating at a speed of 1600Hz supported by magnetic bearings.
Observational signatures of photon interactions in a gamma-ray burst environment Laura Paulucci UFABC
Photonuclear reactions are usually disregarded in any analysis of radiation effects in astrophysical environments due to small number of high energy photons, low ISM density and low cross section for this process. Nevertheless, in a gamma ray burst the amount of photons in the energy range consistent with the nuclear giant resonance, for which the photonuclear reaction cross section is substantially enhanced, specially for high mass nuclei, is quite significant. We analyze the passage of photons with energies in the range 7 - 30 MeV, with distribution consistent with a Band function in matter with characteristics similar to the one thought to exist in a gamma ray burst environment. We present results of the expected change in the relative abundance of elements in a shell surrounding the GRB obtained by using the Geant4 package. We discuss the possibility of observable effects (emission lines from decaying elements in short, medium and long timescales) and compare our results with the predicted nucleossinthesys in the supernova scenario. We show that the effects of photonuclear reactions should not be neglected.
Cosmological simulations of galaxy formation Leonardo Pellizza IAFE
Cosmological simulations of galaxy formation According to the standard cosmological model, the structure observed in the Universe arised from the growth of primordial density fluctuations. The process was mainly driven by gravitation, that produced the collapse of dark matter into halos. These halos grew and merged, clustering in a hierarchical way. Within them, baryonic matter cooled down and produced stars, leading to the formation of galaxies. The whole process is highly non-linear, involving the coupled dynamics of dark matter and baryons, and the thermodynamics of the latter. Hence, the best way to study it is through numerical simulations. In this talk, I will discuss the physics of the formation and evolution of galaxies, and give an overview of the numerical tools developed to describe the process. Finally, I will present the most relevant results in the area. Stellar-mass compact objects in comological simulations Stellar-mass compact objects are the engines driving the emission of different kind of sources, such as gamma-ray bursts or X-ray binaries. Recent works claim that the emission of these sources are a major component of the energy feedback of the stellar populations into the interstellar and intergalactic media. Hence, it should play an important role in different processes, such as the formation of galaxies or the ionization and thermal history of the Universe. The importance of this feedback component depends on the rate of production of stellar-mass compact objects, and the luminosity of the sources powered by them. Recent observational and theoretical works claim that both of these depend on the chemical enrichment of the stellar populations from which compact objects form. Using numerical simulations of galaxy formation in a cosmological framework, our group developed models to describe the populations of stellar-mass compact objects at different stages of the evolution of the Universe, and assess their influence on the surrounding medium. In this talk I will describe these models, and present our preliminary results.
COSMIC RAY SIGNALS IN THE MASS RESONANT MARIO SCHENBERG GRAVITATIONAL WAVE DETECTOR Luiz Augusto Stuani Pereira INPE
One of the phenomena predicted by Einstein in the derivation of general relativity is the existence of small perturbations of the metric that he named gravitational waves. The direct detection of gravitational waves is one of the main objectives of science of the XXI century. To increase the chance of this detection we need to increase the experimental apparatus detection sensitivity to measure the spacetime deformation and learn about the different noises present in these complex experiments. Among them there are those from cosmic rays in mass resonant gravitational wave detectors. Therefore one of the systems coupled with the detector with the purpose to minimize the noise from cosmic ray particles is the veto system of cosmic rays, as the one installed at the gravitational detector NAUTILUS, in Italy. The cosmic ray veto does not only identify the signals due to cosmic rays, but also allows the study of the gravitational antenna performance through acoustic signals produced by cosmic radiation, aiding the development of more accurate detection systems. This work aims the study of the noise generated by cosmic rays in the Mario Schenberg gravitational wave detector, located at the IF-USP São Paulo. Single hadron flux measurements held in the northern hemisphere were used to calculate the expected flux of these particles in São Paulo city. It is made a Monte Carlo simulation of the passage of this flux through the antenna and the building where it is installed using the Geant4 toolkit from CERN in order to determine the energy deposited in the antenna normal mode using the multipoint thermo-acoustic model. Through this study we get a better knowledge of the noise generated by cosmic rays in gravitational wave detector and how this signal can be used to calibrate the antenna response function.
Dynamical instability of white dwarfs and breaking of spherical symmetry under the presence of extreme magnetic fields Manuel Malheiro ITA
In this work we discuss some basic properties of the equilibrium of magnetized white dwarfs, in particular the condition for dynamical instability of the star in the presence of an extremely large magnetic field. This will be done in the context of the virial theorem extended to include a magnetic term. We show, following the work of Chandrasekhar and Fermi of 1953, that when the star magnetic energy exceeds its gravitational potential energy, the system becomes dynamically unstable. In that seminal work it was shown that for extreme magnetic fields, a sphere is not the equilibrium configuration, and the star will become an oblate spheroid contracted along the symmetry axis. In light of this, the new mass limit for very magnetized and spherical white dwarf M = 2.58 solar Masses, recently calculated, should be considered carefully, since these objects are unstable and unbound, and also because the extreme magnetic fields violate the spherical symmetry assumed to obtain the aforementioned limit.
Stellar entropy and stellar evolution: a brief review Marcio de Avellar LAG
We review the concepts of thermodynamic and information entropy as applied to Stellar Astrophysics. We track and discuss the actual decrease of the thermodynamic entropy from the very beginning of a star s life, as a gas cloud collapses to form one, and the next steps of its evolution up to the ultimate formation of a black hole (for a fixed baryon mass ideal object), when entropy finally rises dramatically. We then discuss the case of actual stars of different masses throughout their evolution, clarifying the role of virial equilibrium condition for the decrease of the entropy and related issues. Next, we discuss how information entropy relates to the thermodynamic entropy, showing that although there is no systematic trend, there is also a decrease of information entropy as (realistic) objects go more compact. We also show that information entropy can be used to discriminate among the composition of neutron/quark stars, more specifically we found that most of the actually observed compact stars should be quark stars. Finally, we discuss how gravity ultimately drives composition, hence structural changes along the stellar evolution all the way till the ultimate collapse to black holes.
Laval nozzle as an acoustic analogue of a massive field Marco Cuyubamba Espinoza Universidade Federal do ABC
Massive fields in the vicinity of black holes have been studied during the last two decades. It was found that their behavior is qualitatively different from the behavior of the massless fields. Since massive fields are short-ranged, we cannot expect the observation of their signal from black holes in near-future experiments. An attractive possibility for experimental study of the massive fields in the background of a black hole is a consideration of the acoustic analogue. We study a gas flow in the Laval nozzle, which is a convergent-divergent tube that has a sonic point in its throat. We show how to obtain the appropriate form of the tube, so that the acoustic perturbations of the gas flow in it satisfy any given wavelike equation. With the help of the proposed method we find the Laval nozzle, which is an acoustic analogue of the massive scalar field in the background of the Schwarzschild black hole. This gives us a possibility to observe in a laboratory the quasinormal ringing of the massive scalar field, which, for special set of the parameters, can have infinitely long-living oscillations in its spectrum.
Measuring galaxy morphologies in the CFHT/MegaCam Stripe-82 Survey Maria Elidaiana da Silva Pereira CBPF
We present the determination of galaxy structural parameters in the CFHT/MegaCam Stripe-82 Survey (CS82) stacked images. The CS82 survey covered an area of $~170$ square degrees with the CFHT $3.6m$ telescope in a field determined by $-40
Thermodynamical Analysis of the Black Hole with a Global Monopole in a f(R) Theory Maria Emilia Xavier Guimaraes UFF
In this work we study the problem of the Black Hole in a region containing a Global Monopole in a f(R) theory of gravity. We use the metric formalism to obtain the field equations in terms of F(R)= df(R)/dR and assume that F(R) is a n-degree function of the radial coordinate. Adopting a linearized approximation of the metric, we obtain a Black Hole solution and analyze the relevant thermodynamical quantities, such as local temperature, energy and heat capacity. We compute the Hawking and the Unruh temperatures in this alternative theory and we compare both of them. They coincide in the General Relativity theory for a Schwarzschild black hole. In this new theory, this very well-known result is not clear.
Pure Neutron Matter in Lower Density Regime Mariana Dutra ITA
The behavior of pure neutron matter (PNM) in lower density regime is a very important subject and need to be explored. It is know that neutrons ($n$) do not form a bound state so, is expected that in lower density regime the neutrons behave like a diluted fermions system. In this regime, the system have only two scales: the scattering length $n-n$ ($a_{nn}$) and the density that is related to the cubic power of Fermi momentum $k_{ m F}$. Recently, the authors of Ref.[1] have proposed a modification of the constraint for this regime. Based on this, the work presents a preliminary study of the behavior for both, non relativistic Skyrme models and relativistic point-coupling ones concerning the analytical investigation of the energy density. Our main goal with such a study is to understand the essential factors that leads these models to present a good description in this regime and also to identify some correlation in its coupling constants. [1] M. Dutra, O. Loureno, A. Delfino {it et al}, Phys. Rev. C {f 85}, 035201 (2012).
High-density quark matter in compact objects Mark Alford Washington University
Lecture 1: Quark matter and the high-density frontier Quark matter is the densest form of matter that the standard mode predicts. In this lecture I will survey our current knowledge of quark matter. I will discuss on the rich variety of postulated color-superconducting phases of quark matter,which includes some that are superfluid, break chiral symmetry, or are even crystalline. Lecture 2: Quark matter in neutron stars If we want to experimentally investigate the phases of quark matter, we must study neutron stars. The core of a neutron star is the only place in the universe where conditions are sufficiently dense and cool that ordered phases of quark matter might exist. I will discuss the challenges of using neutron stars as a laboratory for quark matter, focusing on the development of astrophysically observable signatures that could tell us whether there is quark matter present in their interior.
SHELL MODEL POTENTIAL FOR ONE-PROTON EMISSION FROM EXOTIC NUCLEI Martha Rodrigues Centro Brasileiro de Pesquisas Físicas
The proton-emitter nuclei are located far from beta-stability line, in the region of very neutron-defcient nuclides, near the so-called proton drip line. The half-lives of proton emission processes have been measured and di®erent phenomenological decay models are able to reproduce the experimental results within the uncertainty values. However, only few attempts were made in using more fundamental models for nuclear structure to evaluate half-lives of these nuclei as, for example, the nuclear shell model. In present work, the valence proton tunnels a potential barrier consisting of the superposition of the Coulomb, centrifugal and the nuclear shell model Wood-Saxon potential form with typical spin-orbit correction. The nuclear potential depth is determined by adjusting the mean value of the valence proton energy to the Q-value of the decay and the nuclear radius parameter is chosen to have the minimum square deviation for all measured half-lives of proton emitters in relation to the experimental ones.
Neutrino oscillations in external fields in curved space-time Maxim Dvornikov UNIVERTY OF MICHIGAN and IMP
I derive the new quasi-classical relativistic equation for the description of the neutrino spin evolution in strong gravitational and electromagnetic fields as well as in dense matter. Using this equation I describe neutrino spin oscillations in these external backgrounds. I apply my results for the studies of neutrino propagation and oscillations in the vicinity of Schwarzschild and Kerr black holes surrounded by an accretion disk. Neutrinos are supposed to interact with a strong magnetic field. In frames of my approach I analyze the recently proposed mechanisms for the explanation of the deficit of UHE neutrinos emitted in GRBs and show that some of them, involving neutrino oscillations, are invalid. References: 1. M. Dvornikov, “Neutrino spin oscillations in matter under the influence of gravitational and electromagnetic fields”, JCAP 06, 015 (2013), arXiv:1306.2659 [hep-ph]. 2. M. Dvornikov, “Neutrino spin oscillations in gravitational fields”, Int.J.Mod.Phys.D 15, 1017 (2006), hep-ph/0601095.
Diffractive photoproduction of charmonia in nuclear collisions at the LHC Mirian Thurow Griep Universidade Federal do Rio Grande do Sul
In this work we investigate the photoproduction of radially excited vector mesons off nuclei in heavy ion relativistic collisions. In particular, we analyze the exclusive photoproduction of Psi(2S) off nuclei, evaluating the coherent and the incoherent contributions to that process. The theoretical framework used in the present analysis is the light-cone dipole formalism and predictions are done for PbPb collisions at the CERN-LHC energy of 2.76 TeV.
Dynamical fluctuations as a probe of QGP formation in heavy ion collisions at high energy Mohammad Ayaz Ahmad University of Tabuk, Saudi Arabia
Fluctuations depend on the properties of the system and may carry significant information about the intervening medium created in the collisions. Underlying dynamics of multiparticle production in relativistic nuclear collisions can be well understood by studying presence of fluctuations in these collisions. Dynamical fluctuations may arise due to some physical processes taking place in the collisions. As an after effect of the formation of QGP, the multiplicity and pseudorapidity distributions of the secondary particles may show large non-statistical fluctuations in some events. An event-by-event analysis of fluctuations will surely help in separating dynamical and statistical fluctuations. Experimental and theoretical understandings and information are merging together to relate the fluctuations with phase transition of the confined hadronic matter to QGP. The power law behaviour of scaled factorial moments (SFMs) on bin size is known as “intermittency”, which can predict the existence of dynamical fluctuations. Evidence of power law behaviour in experimental data of e+e- annihilation, -nucleus, hadron-hadron, hadron-nucleus and nucleus-nucleus collisions have been found. Thus, intermittency seems to be a general property of multiparticle production. No single mechanism has been found to explain the intermittency. For this purpose, two stacks of BR-2 emulsion exposed to 4.5A GeV/c silicon and carbon beams at Synchrophasotron of Joint Institute of Nuclear Research (JINR), Dubna, Russia, and also two stacks of Fuji type of emulsion exposed to 14.6A GeV/c at Alternating Gradient Synchrophasotron (AGS) of Brookhaven National Laboratory (BNL), NewYork, USA, have been utilized for data samples. The method of line scanning has been adopted to scan the stacks, which was carried out using Japan made NIKON (LABOPHOT and Tc-BIOPHOT) high resolution microscopes with 8 cm movable stage using 40X objectives and 10X eyepieces. The interactions due to beam tracks making an angle < 2 to the mean direction and lying in emulsion at depths > 35 m from either surface of the pellicles were included in the final statistics. Using the data samples of 701 events of 28Si-Em interactions, 844 events of 12C-Em interactions at 4.5A GeV/c and 415 events of 28Si-Em interactions at 14.6A GeV/c, we have studied the existence of event-by-event dynamical fluctuations by using the methods of scaled factorial moments (SFMs), Fq and modified multifractal moments, Gq. The experimental results have also been compared with correlated event generators FRITIOF and UrQMD models and also uncorrelated Lund Monte-Carlo model. The analysis of SFMs gives an evidence for an intermittency pattern of fluctuations and supports a self-similar cascade mechanism.
Points of General Relativistic Shock Wave Interaction are ”Regularity Singularities” where Spacetime is Not Locally Flat Moritz Reintjes University of Michigan - Ann Arbor (and IMPA)
In this talk I am going to present the results of our recent paper, in which we show that the regularity of the gravitational metric tensor cannot be lifted from Lipschitz continuity ($C^{0,1}$) to continuous differentiability by any $C^{1,1}$ coordinate transformation in a neighbourhood of a point of shock wave interaction in General Relativity, without forcing the determinant of the metric tensor to vanish at the point of interaction. This is in contrast to Israel’s celebrated 1966 Theorem, which states that such coordinate transformations always exist in a neighbourhood of a point on a smooth single shock surface. The results imply that points of shock wave interaction represent a new kind of singularity in spacetime, singularities that can form from the evolution of smooth initial data, but at which spacetime is not locally Minkowskian under any coordinate transformation. In particular, at such singularities, delta function sources in the second derivatives of the gravitational metric tensor exist in all coordinate systems, but due to cancelation, the Riemann curvature tensor remains uniformly bounded. (The authors currently work on the question, whether regularity singularities cause detectable physical effects, e.g. in gravitational radiation.)
A mathematical model for the determination of pulsars braking indices Nadja S. Magalhães FEDERAL UNIVERSITY OF SAO PAULO
The theoretical determination of braking indices of pulsars is still an open problem. In this work I will report results of an study concerning such determination based on a modification of the canonical model, which admits that pulsars are rotating magnetic dipoles, and on data from the seven pulsars with braking indices calculated from observational data.
Effective mass, nuclear matter incompressibility, symmetry energy and slope correlations. Odilon Lourenço Universidade Federal de São Carlos
In this work we show how the effective mass of relativistic mean-field (RMF) models can reveal correlations with the nuclear matter incompressibility. We have verified a linear dependence of the incompressibility (K) as a function of the skewness parameter at the saturation density for fixed values of the effective mass. The results confirm the findings of Khan and Margueron [1]. The same result is found when the dependence of K as a function of its first derivative is analyzed. Such a quantity is strongly related to the experimental data of the centroid energy of the giant monopole resonance. In order to have analytical expressions in our study, we consider the Point-Coupling version of the usual RMF models added with the approximation of equal scalar and vector densities in the models. Such an approximation is very robust when the densities (ρ) are lower than the nuclear matter saturation density (ρo). In the same regime we discuss the crossing density (ρc) for different effective masses. The results are very promising to further investigations about correlations among nuclear matter observables at a low density regime where expansions for incompressibility, symmetry energy and its slope are important. [1] E. Khan and J. Margueron, arXiv:1304.4721v1 [nucl-th].
Dark matter interaction a with dark energy model described by a time dependent equation of state Rafael da Costa Nunes Universidade Estadual do Rio Grande do Norte
In this work we investigate the interaction between dark matter and dark energy for a coupling following the Wang-Meng decaying law and the Barboza-Alcaniz dark energy parametric model. This dark sector interaction scenario has three free parameters which are constrained with the most recents data of type Ia supernovae, baryon acoustic oscillations, cosmic microwave background and the Hubble expansion rate function. Although the results are entirely consistent with the $Lambda$CDM model, we show that interaction in dark sector can not be rule out by the current observational data.
Uso de Coordenadas Observacionais em modelos cosmológicos não homogêneos Ricardo Gomes Universidade do Estado do Rio de Janeiro
O atual modelo padrão da Cosmologia pressupõe que em primeira aproximação o universo em larga escala seja homogêneo e isotrópico. Isso significa que em escalas maiores de $300$ mega parsec (Mpc), onde $1$ parsec é aproximadamente $3$x$10^{22}$ metros, a métrica tenha componentes e não dependam da posição e é determinada a menos de uma função e de um parâmetro. Esta descrição só é válida para largas escalas já que observamos uma vastidão de estruturas como galáxias, aglomerados de galáxias, filamentos, etc. No entanto essa observação até certo ponto grosseira parece dar conta de uma série de observações (cada vez mais precisas através do advento dos novos instrumentos de observação). O conceito de Coordenadas Observacionais, introduzido por Ellis extit{et al}. $(1985)$, visa trazer uma cosmologia "interpretável" através das observações astrofísicas, a fim de confrontar com as previsões teóricas sem induzir hipóteses sobre a geometria (somente a homogeneidade e isotropia). Dessa forma caracteriza-se em detalhe como as observações cosmológicas podem ser utilizadas para determinar a geometria do espaço-tempo. Diferente do que é feito atualmente, ou seja, dado um modelo cosmológico, analisamos quais observações podem ser realizadas e predizemos quais resultados as observações devem ter, em Coordenadas Observacionais, dado o resultado das observações, busca-se determinar o tipo de matéria que constitui o universo e como estas delimitariam a geometria do espaço-tempo. Nesta trabalho buscamos dominar o conceito de Coordenadas Observacionais a fim de adaptá-lo levando a um modelo possivelmente não homogêneo. Com isso, visamos confrontar o modelo derivado com as observações atuais, esperando tirar conclusões sobre o uso desse tipo de coordenada e analisando o que a hipótese de um modelo não homogêneo pode trazer de novidade na interpretação das observações cosmológicas.
Proton superconductivity and the masses of neutron stars Rodrigo Picanco Negreiros UFF
The unexpected temperature evolution of the neutron star in the Cassiopeia A supernova remnant (Cas A, for short) has renewed tremendous interest in the cooling mechanisms of neutron stars. In particular, the formation of superconducting protons and superfluid neutrons deep inside the cores of neutron stars have become focal points of the discussion. The purpose of this work is to add a new aspect to this discussion, which focuses on the connection between proton superconductivity and the masses of neutron stars. Assuming (as is currently the case) that the temperature evolution of Cas A is largely controlled by superconducting protons, we study a series of phenomenological proton-pairing models to determine how deep into the stellar core superconducting protons actually penetrate. This allows us to establish a heretofore unknown relationship between the mass of the neutron star in Cas A and the penetration depth of the superconducting proton phase. This relationship can be used to either predict the depth of the superconducting proton phase, or, conversely, determine the mass of Cas A from a reliable calculation of the size of the proton superconducting phase in superdense neutron star matter. We emphasize that the strategy outlined in this work can be applied to any other neutron star of similar age, whose temperature might be reliably monitored over a several years period. High-mass neutron stars, such as the recently discovered neutron stars J1614-2230 ($1.97 pm 0.04, msun$) and J0348+0432 ($2.01 pm 0.04 , msun$), appear particularly appealing as a significant fraction of the protons in their cores may be superconducting.
The Dark Energy Survey: an overview Rogerio Rosenfeld IFT-UNESP, ICTP-SAIFR and LIneA
We present an overview of the Dark Energy Survey and its prospects to measure cosmological parameters from a combination of observational probes.
Oscillon formation due to symmetry changes Romulo Tavares Uerj
In many scalar field theories there are structures that retain their shapes indefinetely in time, as domain walls, solitons, q-balls. These are topologically stable solutions of the field equations of motion. There are, however, other solutions not topologically stable neither constant in time, but that can survive for several field oscillations. These are field configurations usually called oscillons. Oscillons are finite energy, localized objects that have no conserved charges, but can retain most part of the field energy and that can be copiously generated after symmetry changes in the system, like for example, during a symmetry breaking. Recent studies show that oscillons can form in many different systems, such as in Newtonian fluids, granular matter and in cosmological models (like after inflation), and then can be potentially important in the physics of the early universe. In this work, we investigate the characteristics of the emergence of oscillons in a two scalar field theory model, where phase transitions occur after a quench on a parameter.
Physically Consistent Probability Density in Noncommutative Quantum Mechanics Ronaldo Vieira Lobato ITA
Noncommutative Quantum Mechanics (NCQM) still presents some open questions, such as, for instance, the study of motion in conguration spaces with boundaries, which leads to the question of how to formulate boundary value problems in this context. As usual, the behavior of the quantum state near the frontiers of the space must be consistent with the value of the probability density at the boundaries. This situation leads us to the issue of dening the probability density in NCQM. The rst natural step into that direction would be to try to use the ordinary denition of Born, well known from Quantum Mechanics (QM), which states that the probability density is the punctual product between the wave function and its complex conjugate. But one can show that this naive attempt fails, since the ordinary denition does not fulll the continuity equation. By the other side, it is well known that in NCQM the punctual product between two functions must be replaced by the Moyal product. So one is led to try to dene the probability density as the Moyal product between the wave function and its complex conjugate. But in this case we must choose the order of the factors, since the Moyal product is nonabelian. If we choose to put the complex conjugate at the right of the product, we nd that the resulting probability density candidate does not fulll the continuity equation, so that this attempt fails too. On the other hand, if we choose to put the complex conjugate at the left, the resulting probability density candidate satises the continuity equation.
HYBRID STARS IN STRONG MAGNETIC FIELDS CONSIDERING A PARAMETRIC HADRONIC MODEL Rosana de Oliveira Gomes Universidade Federal do Rio Grande do Sul
We investigate the eects of strong magnetic elds on the properties of a multicomponent system, composed by a hadronic and a quark phase, that are independent. The hadronic phase is described by an extension of ZM Model in which the coupling of hadrons and mesons is parameterized by means of a parameter , that will be related to the eective mass of nucleon. The quark phase is described by the M.I.T. bag model, where the quarks are considered to be asymptoticaly free in a space region denominated bag. The presence of strong magnetic elds aects the equation of state (EoS) of each phase by Lan- dau quantization. We also include the anomalous magnetic moment (AMM) of nucleons, hyperons, quarks and leptons in our formalism in order to analyse its eects on the population and EoS. Two parameterisations of a density dependent static magnetic eld are considered, reaching 2-4x10^18 G in the center of the star. In order to describe a hybrid star, we perform a hadron-quark phase transition of rst order following the Gibb's criteria, allowing the appearence of the mixed phase. Imposing global electric charge and baryonic charge conservation, the pressure is assured to grow constinuously through the mixed phase. Finally, the Tolman-Oppenheimer-Volkov (TOV) equations are solved, showing the dependence of the mass-radius relation and population of hybrid stars on the models' parameters, strong magnetic elds, AMM and dierent hyperonic coupling schemes.
Solutions of Einstein-Maxwell Field Equations for a Dipole Magnetic Field Rubens Marinho Instituo Tecnológico de Aeronáutica
We use the symmetry reduction technique due to Stanley Steinberg to obtain the solution of the Einstein-Maxwell Field Equations for the case of dipole magnetic field. This technique is based on the invariance of the partial differential equations under the Lie groups of symmetries. With the help of the infinitesimal generators of the group, the Lie algebra, we are able to reduce the partial differential equations to a more manageable ordinary differential equations.
Stability of accretion using the effective metric Santiago Esteban Perez Bergliaffa UERJ
The evolution of perturbations of a background which is a solution of a nonlinear field theory is governed by the effective metric. As shown by Moncrief , the linear stability of the accretion of a fluid onto a Schwarzschild black hole can be studied by means of an integral of the energy-momentum tensor defined by the effective metric. We shall briefly review these results, and present the details of their application to the accretion of a nonlinear scalar field onto a Schwarzschild black hole
Spinning cosmic strings in Brans-Dicke theory of gravitation Sergio Mittmann dos Santos IFRS, Campus Porto Alegre
The Brans-Dicke gravitation indicates the possibility of the existence of objects called cosmic strings, approximately one-dimensional and very dense lines, which connect different regions created nanoseconds after the Big Bang, reaching the length of the known Universe. They are considered topological defects, which arose from a spontaneous symmetry breaking. There is a kind of cosmic string poorly understood, called spinning cosmic string, whose dynamics is associated with solution of Godel to the equations of general relativity, which suggests the theoretical possibility of closed timelike curves. In Brans-Dicke gravitation, attempts to find solutions for spinning cosmic strings always restricted for approximations with an unique form field, previously defined, leading to not very significant scenarios. In this work, we present a model for spinning cosmic strings, developed from the Brans-Dicke theory of gravitation, where the field equations admit a general form. The model consists of a 6 coupled nonlinear differential equations system. The analytical solutions found so far for this system will be shown and a discussion on the contribution of these solutions to better understand the dynamics of spinning cosmic strings will be held.
Schenberg Detector Dilution Refrigerator Vibration Isolation Sergio Turano de Souza UNICSUL
A spherical gravitational wave (GW) detector has a heavy ball shaped mass which vibrates when a GW passes through it. Such motion is monitored by transducers and the respective electronic signal is digitally analyzed. One of such detectors, SCHENBERG, will have resonant frequencies around 3.2 kHz with a bandwidth near 200 Hz. Mário Schenberg is a spherical ressonant-mass gravitational wave detector weighting 1.15ton, being built in the Departament of Materials at the University of São Paulo. The sphere with 65cm in diameter made of a copper-aluminum alloy with 6 per cent Al.The frequencies of running resonant-mass detectors typically lay below 1 kHz, making the transducer development for this higher frequency detector somewhat more complex. Coaxial cables are use to carry microwaves to the Schenberg parametric transducers. The sphere, in a commissioning fase the detector is cooled to 4.2 Kelvin. In the next fase will be cooled down to a lower temperature using a dilution refrigerator, this temperature could reach as low as 50 mK. This refrigerator produces noise because of the Helium evaporation and this noise is transported by the connections to the sphere. In this work we the study such vibration noise and how it could be minimized. The conventional method used in detectors with this kind of refrigerator is to connect the refrigerator to the sphere using thin copper wires, but it reduces the cooling capability by a great factor. The vibration attenuation should make the dilution refrigerator noise lower than the thermal vibration noise on the sphere surface keeping the temperature as lower as possible. An attenuation higher than 10^10 is found.
Dissipative effects and thermalization properties in warm inflation SILVIO ANDRADE UNIVERSIDADE DO ESTADO DO RIO DE JANEIRO - UERJ
In warm inflation the field that drives the accelerated expansion of the universe, termed as inflaton, interacts with other fields along the period of inflation. The interactions of the inflaton with other fields imply that the effective evolution equation for the inflaton will in general have terms representing dissipation of energy out of the inflaton system and into other particles and also a stochastic noise, according to the fluctuation-dissipation theorem. Thus, in this picture there are radiation energy production and the reheating phase from standard model inflation is not in general necessary in warm inflation. In this work we study the warm inflation model by fully accounting its interaction with the radiation fluid. Both bulk and shear viscosities, characterizing the dissipative properties of the radiation fluid, are accounted for. We analyze the effects of bulk and shear viscosities in the dynamics of the perturbations at linear order and how they affect the amplitude of the curvature power spectrum. We also study the thermalization features of the inflaton perturbations, guided by the fluctuation-dissipation properties expected from statistical physics in general.
Exotic Matter in Compact Stars - Limits and Consequences Stefan Schramm FIAS
The mass measurements of two heavy neutron stars, both with values of two solar masses have intensified the discussion about the possibility of exotic particles in compact stars in recent years. This includes hyperons, quarks, and kaon or other condensates. I will discuss limits for exotica in different hadronic and quark-hadron model formulations. In addition, I will investigate possible constraints from the low-density and high-temperature region of strong interactions on the structure of compact stars. I will discuss the cooling behavior of hybrid stars, especially those with a large mixed phase. Here, potential fast cooling generates severe constraints on the properties of the matter. Finally, the effect of strong magnetic fields on the structure and shape of the compact star will be investigated.
Thermal Casimir effect for spinor fields in the closed cosmological models with cosmic string Valdir Bezerra UFPB
We calculate the total internal energy, total energy density and pressure and the free energy for the spinor field in closed Friedmann spacetime with a cosmic string. We show how the presence of the cosmic string manifests itself and how it influences the results as compared with a scenario in which the cosmic string is absent. The low and high temperature limits are also studied for the Casimir thermodynamical quantities, namely, entropy, pressure and internal energy.
Phase transitions of strongly interacting matter within non-local PNJL model Valeria Pagura IFLP - CONICET
In the framework of non-local SU(2) chiral quark models with Polyakov loop, we study the deconfinement and chiral restoration critical temperatures for both real and imaginary chemical potential. Our results are compared with those obtained within the standard local Polyakov-Nambu-Jona-Lasinio (PNJL) model and with lattice QCD calculations when available.
Stability of Self-Gravitating Disks with Magnetic Field Vanessa Pacheco de Freitas Centro Brasileiro Pesquisas Físicas - CBPF
We can use the "displace, cut and reflect" method to construct exact solutions of Einstein Equations that represents disklike distribution of matter. This method can be applied in the description of galaxies and accretion disks and consists on the introduction of a discontinuity in the first-order derivative of the metric tensor. What we obtain is a solution with a singularity of the Dirac delta type. Our purpose was to apply the method to generate a thin disk from Gutsunaev-Manko solution, which is the representation of a massive object with magnetic field configuration with dipolar symmetry. We studied the stability of test-particles orbits at the disk, generalizing the Rayleigh criteria of stability and introduced a second analysis to test the stability of the disk through a perturbation in the energy-momentum tensor.
Calibration Device Control for Schenberg Detector Wilson Ruiz IFSP
The goal of this work is to give an option to the control of a calibration device that will generate a gravitational tide periodic signal (not a gravitational wave) making use of tools like the FPGA deterministic operational systems. Such signal will be used by Schenberg spherical resonant-mass gravitational wave detector as a reference for calibration. As the detector, being built in the Physics Institute at São Paulo University with a central frequency of 3200 Hz and a bandwidth of +- 200 Hz, the device must rotate at a frequency of 1600 HZ, in a very stable way. The objective of this work is find tools for rotation control of the device with two mass that will generate a stable gravitational signal that will be read by Mario Schenberg detector and be used for a extra calibration procedure.
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