Pescara - Abstracts
 Aharonian Felix Title: The Nature's perfectly designed Extreme Accelerators Abstract: I will discuss the implications of recent results from space- and ground- based observations with emphasis on the phenomena related to the so-called extreme particle accelerators - the perfectly designed machines which accelerate particles with a rate close to the theoretical limit. Belvedere Riccardo Title: Mass, Radius and Moment of Inertia of Neutron Stars Abstract: We formulate and integrate numerically the set of self-consistent ground-state equilibrium equations for neutron stars taking into account quantum statistics, electro-weak and strong interactions within the framework of general relativity. The strong interaction between nucleons in the neutron star core is modelled through the sigma-omega-rho meson exchange in the context of the extended Walecka approach. This solution differs from the traditional one in that the global charge neutrality is imposed as contrasted to the local charge neutrality. The electrodynamical structure in the interface between the core and the crust is examined and the presence of overcritical electric fields inferred. Specific examples of equilibrium configuration are given fulfilling the Einstein-Maxwell-Thomas-Fermi equations with the boundary conditions implying a precise eigenvalue problem. Bianco Carlo Luciano Title: The canonical GRB scenario Abstract: Within the fireshell model, Gamma-Ray Burst (GRB) light curves are composed by two distinct phenomena: the Proper GRB (P-GRB), emitted when the fireshell becomes transparent, and the extended afterglow, emitted due to the interaction with the CircumBurst Medium (CBM) of the ultrarelativistic baryonic matter shell left over after the transparency point. The peak of the extended afterglow, together with the P-GRB, forms what is usually called the "prompt emission". Such a theoretical framework implies the existence of three GRB classes, as a function of the fireshell baryon loading and of the CBM average density: the "genuine" short GRBs, where the P-GRB is energetically predominant over the extended afterglow, the "long" GRBs, where the extended afterglow is energetically predominant over the P-GRB, and the "disguised" short GRBs, where the extended afterglow, although still energetically predominant, has a peak flux lower than the P-GRB one due to a peculiarly low value of the CBM density, typical of galactic halos. In this talk I will describe the kinematics and dynamics of the fireshell in both the optically thick and the optically thin phase, with special emphasis on the transparency point and on the observational properties of the P-GRB. Such observational properties are crucial for the identification of the P-GRB in the observed GRBs and therefore for their classification in the above recalled three classes. Boshkayev Kuantay Title: On the minimum rotational period of fast rotating white dwarfs 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 fast rotating white dwarfs as a function both of the central density and the rotational period of the star. The minimum rotational period (maximum angular velocity) for stable configurations has been obtained as well as the contribution of rotation to the maximum mass of white dwarfs. Casolino Marco Title: Recent PAMELA measurements of proton and helium nuclei and cosmic ray acceleration in the galaxy Abstract: In this work we will present the measurements of Pamela proton and helium nuclei in the rigidity range 1 GV 1.2 TV. The data show that proton and helium nuclei have different spectral indexes, suggesting that the two particles must undergo different acceleration mechanism or be accelerated at different sites. Furthermore both spectra show a deviation from the power law around 230GV, hinting at an additional source which becomes detectable around these rigidities. The data will be discussed in light of the measurements coming from balloons, extendend air shower and gamma ray telescopes. Han Wenbiao Title: Generation of electromagnetic field energy in gravitational collapses Abstract: We abandon the assumption of the exact local neutrality of gravitationally collapsing cores at/over nuclear density, as protons and electrons are differently coupled to fundamental electroweak, strong and gravitational fields. Using Thomas-Fermi solutions that give non-trivial electric fields on the surface of cores as an initial condition, we integrate the continuous equation, energy-momentum conservations, Maxwell equation and equations of states in a gravitationally collapsing process, we find strong oscillating electric fields and large electromagnetic energy density in the neighbourhood of collapsing core's surface, which can possibly be account for Gamma-Ray Bursts. Jones David Title: Multi-wavelength surveys of the Galactic centre Abstract: Here I review the phenomenology of the Galactic centre region, which constitutes our closest view of a galactic nucleus. I will review past and present surveys/observations of the region and conclude with some examples of the (particle) physics that one can do with these surveys. Kafexhiu Ervin Title: Excitation and destruction of nuclei in hot astrophysical plasmas around black holes Abstract: The importance of nuclear reactions in low-density astrophysical plasmas with ion temperatures $T \geq 10^{10}$ K has been recognized for thirty years. However, the lack of comprehensive data banks of relevant nuclear reactions and the limited computational power have not previously allowed detailed theoretical studies. Recent developments in these areas make it timely to conduct comprehensive studies of the nuclear properties of very hot plasmas formed around compact relativistic objects such as black holes and neutron stars. Such studies are of great interest in the context of scientific programs of future low-energy cosmic gamma-ray spectrometry. In this work, using the publicly available code TALYS, we have built a large nuclear network relevant for temperatures exceeding $10^{10}$ K. We then study the evolution of hot accretion plasmas for such high temperatures due to the destruction of nuclei at inelastic collisions, calculate the resulting gamma-ray spectra due to the superposition of prompt excitation gamma-ray lines, and present the results on the abundances of D, T, $^3$He. Lefa Eva Title: Time-dependent modeling of the energy spectra of gamma-ray blazars Abstract: The TeV gamma-ray spectra of some BL Lacs, after being corrected for intergalactic absorption in the extragalactic background light, appears unusually hard. This finding poses challenges to conventional acceleration and emission models. We analyze the constraints to produce such hard TeV spectra within a time-dependent, leptonic synchrotron-Compton approach. We examine two types of electron distributions, power-law with high value of "low energy cut-off" and relativistic Maxwellian distribution. Malheiro Manuel Title: SGRs and AXPs: Massive Rotating White Dwarfs versus Magnetars Abstract: The recent observations of SGR 0418+5729 offer an authentic Rosetta Stone for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). It is shown how a consistent model for SGRs and AXPs can be expressed in terms of canonical physics and astrophysics within massive, fast rotating, and highly magnetized white dwarfs. Menegoni Eloisa Title: Cosmological Constraint on Fundamental Constants Abstract: The CMB anisotropies provide a unique opportunity to constrain simultaneous variations of the fine-structure constant \alpha and Newton's gravitational constant G. Those correlated variations are possible in a wide class of theoretical models. I'll show that the current data, assuming that particle masses are constant, gives no clear indication for such variations, but already prefers that any relative variations in $\alpha$ should be of the same sign of those of $G$ for variations of 1 %. Pandolfi Stefania Title: Theoretical Development toward the Planck mission Abstract: The importance of considering an extended cosmological scenario beyond the standard LCDM model is increasingly more timely looking forward the release of the data form the Planck mission. Piano Giovanni Title: Gamma-ray emission from the SNR Gamma Cygni: the AGILE results Abstract: The SNR Gamma Cygni is located within one of the most complex site of intense gamma-ray emission, i.e. the Cygnus region. I will present the AGILE-GRID data related to the the first-two-year observations of the region. Gamma-ray emission from the SNR region is dominated by the pulsar PSR J2021+4026. I will show that, after "subtraction" of the intense pulsar emission, a clear pattern of residual gamma-rays is detected with a distinct morphology. This emission can be related to non-thermal high-energy gamma-rays produced by shock-accelerated hadronic particles. Pugliese Daniela Title: What do we learn about the Reissner-Nordstrom geometry? Abstract: Investigate the motion of neutral test particles in the gravitational field of a charged mass described by the Reissner-Nordstr\"om (RN) spacetime. We focus on the study of circular stable and unstable orbits around configurations describing either black holes or naked singularities. We show that at the classical radius there exist orbits with zero angular momentum due to the presence of repulsive gravity. The analysis of the stability of circular orbits indicates that black holes are characterized by a continuous region of stability whereas in the case of naked singularities the region of stability can split into two non-connected regions inside which test particles can remain orbiting unchanged. Rangel Lemos Juracy Title: Luminosity function of BATSE GRBs whose prompt emission is not dominated by the P-GRB Abstract: Schmidt [ApJ, {\bf 700}, 633 (2009)] did a statistical analysis on the GRB prompt emission data of the GUSBAD catalog [Schmidt, ApJ, {\bf 616}, 1072 (2004)], a collection of sources from the BATSE detector composed by himself. In this analysis it is assumed that GRBs are described by five different Gaussian luminosity functions, which correspond to five spectral classes obtained from the four channels of the BATSE detector. He used a GRB sample with redshift from Swift to calibrate the luminosity function. He uses the Euclidean value of $V/V_{max}$ as a cosmological distance indicator, since GUSBAD sources do not have measured redshift. He obtained a correlation $V/V_{max}$ vs $E_{pk}^{ob}$, and then $L_{iso}$ vs $E_{pk}$. He also obtained the Malmquist bias for GRBs with lower energy, because they are not detected for large redshifts. In the Fireshell model, GRB prompt emission is formed by two phases due each one a particular physical process: the P-GRB and the Extended Af terglow Peak [Ruffini et al., AIP Conference Proceedings, \textbf{1132}, 199 (2009)]. The first one is produced at the Fireshell transparency, the second by the subsequent interaction between the optically thin fireshell and the Circumburst Medium (CBM). We therefore repeated the same statistical analysis of Schmidt (2009), but with two main differences; in the first, we used a sanitized" GUSBAD sample, excluding GRBs whose prompt emission is dominated by the P-GRB emission; and in the second, we used the GRB rate density obtained by Wanderman \& Piran [MNRAS, \textbf{406}, 3, 1944 (2010)], instead that obtained by Schmidt (2009). Rieger Frank Title: Particle acceleration and gamma-ray production in the vicinity of supermassive black holes. The case of M87 Abstract: The detection of rapidly variable TeV emission on timescales of  about one day in the nearby radio galaxy M87 implies a source size of a few Schwarzschild radii only. Recent radio imaging has shown that the TeV variability is accompanied by an increase in the radio flux very close to the core, providing further evidence that the required energetic charged particles are accelerated in the vicinity of the central black hole itself. Motivated by this, I will discuss magnetospheric models, where the relevant non-thermal processes are considered to occur at the base of a rotating black-hole-jet magnetosphere. Rotondo Michael Title: On the Thomas-Fermi treatment of compressed atoms and nuclear matter cores of stellar dimensions Abstract: The Feynman, Metropolis and Teller treatment of compressed atoms is extended to the relativistic regimes. Each atomic configuration is confined by a Wigner-Seitz cell and is characterized by a positive electron Fermi energy. The non-relativistic treatment assumes a point-like nucleus and infinite values of the electron Fermi energy can be attained. In the relativistic treatment there exists a limiting configuration, reached when the Wigner-Seitz cell radius equals the radius of the nucleus, with a maximum value of the electron Fermi energy $(E_e^F)_{max}$, here expressed analytically in the ultra-relativistic approximation. The corrections given by the relativistic Thomas-Fermi-Dirac exchange are also evaluated. The dependence of the relativistic electron Fermi energies on compression are compared and contrasted, for selected nuclei, to the non-relativistic ones and to the ones obtained in the uniform approximation. The relativistic Feynman, Metropolis, Teller approach here presented overcomes some difficulties in the Salpeter approximation generally adopted for compressed matter in physics and astrophysics. The extrapolation of this treatment to compressed nuclear matter cores of stellar dimensions with $A\simeq (m_{\rm Planck}/m_n)^3 \sim 10^{57}$ or $M_{core}\sim M_{\odot}$ is also discussed. Rueda Jorge A. Title: The relativistic Feynman-Metropolis-Teller theory for white-dwarfs in general relativity Abstract: The recently formulation of the relativistic Thomas-Fermi model within the Feynman-Metropolis-Teller theory for compressed atoms, is applied to the study of general relativistic white-dwarf equilibrium configurations. Our equation of state takes into account the beta equilibrium and the Coulomb interaction between the nuclei and the surrounding electrons and it is obtained as a function of the compression by considering each atom constrained in a Wigner-Seitz cell. These equations modify the ones used by Chandrasekhar by taking into due account the Coulomb interaction between the nuclei and the electrons as well as inverse beta decay. They also generalize the work of Salpeter by considering a unified self-consistent approach to the Coulomb interaction in each Wigner-Seitz cell. The consequences on the numerical value of the Chandrasekhar-Landau mass limit are presented. The modifications of the mass-radius relation for $^4$He and $^{56}$Fe white-dwarf equilibrium configurations are also presented. Sabatini Sabina Title: Transient gamma-ray emission from the Microquasar Cygnus X-1 Abstract: Cygnus X-1 is the archetypal black hole bynary system in our Galaxy. We report the main results of an extensive search for transient emission from Cygnus X-1 carried out in the energy range 100 MeV- 3 GeV by the AGILE satellite during the period 2007 July - 2011 March. We will focus on two episodes of significant gamma-ray emission occurred on a 1-2 days time scale. Sahakyan Narek Title: Gamma-rays from giant radio lobes of Centaurus A Abstract: Recently Fermi LAT collaboration reported the detection of high energy gamma-ray signal from giant lobes of the radio galaxy Centaurus A. We discuss the origin of this radiation and the possible leptonic and hadronic radiation mechanisms. We show that gamma- rays from giant radio lobes of Centaurus A radio galaxy is explained as interaction of relativistic protons with the ambient low density plasma. Vercellone Stefano Title: The brightest gamma-ray blazar: 3C 454.3 (Crazy Diamond) Abstract: Since 2007, the blazar 3C 454.3 has become the most active and the brightest gamma-ray source of the sky, deserving the nickname of Crazy Diamond''. In this talk, I will review almost four years of observational properties of this remarkable source, discussing both short-term flaring episodes, and long-term monitoring multi-wavelength campaigns. Xue She-Sheng Title: A general relativistic Thomas-Fermi treatment of neutron star cores Abstract: We formulate the set of self--consistent ground--state equilibrium equations for neutron star cores taking into account quantum statistics, electro--weak, and strong interactions, within the framework of general relativity. The strong interaction between nucleons is modeled through the sigma--omega--rho meson exchange in the context of the extended Walecka model, all duly expressed in general relativity. We found the generalization to the works of Klein (1949), of Kodama and Yamada (1972), and of Olson and Baylin (1975) by demonstrating that the thermodynamic equilibrium condition of the constancy of the Fermi energy of each particle--specie can be properly generalized to include the contribution of all fields. The consequences of these new conditions of equilibrium on the structure of neutron stars are discussed.

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