General Relativistic effect on the energy deposition rate for neutrino pair annihilation above the equatorial plane along the symmetry axis near a rotating neutron star
Ritam Mallick, Abhijit Bhattacharyya, Sanjay K. Ghosh, Sibaji Raha
备注：
17 pages, 5 figures
发表信息：
International Journal of Modern Physics E Vol. 22, No. 2 (2013) 1350008
The estimate of the energy deposition rate (EDR) for neutrino pair annihilation has been carried out. The EDR for the neutrinos coming from the equatorial plane of a rotating neutron star is calculated along the rotation axis using the Cook-Shapiro-Teukolsky (CST) metric. The neutrino trajectories and hence the neutrino emitted from the disk is affected by the redshift due to disk rotation and gravitation. The EDR is very sensitive to the value of the temperature and its variation along the disk. The rotation of the star has a negative effect on the EDR; it decreases with increase in rotational velocity.
We study the neutrino pairs annihilation into electron-positron pairs ($ν+{\bar ν}\to e^- + e^+$) near the surface of a neutron star. The analysis is performed in the framework of extended theories of gravity. The latter induce a modification of the minimum photon-sphere radius ($R_{ph}$) and the maximum energy deposition rate near to $R_{ph}$, as compared to ones of General Relativity. These results might lead to an efficient mechanism for generating GRBs.
Energy Deposition by Galactic Cosmic Rays and Implications for Ozone Chemistry
Instituto de Física da Universidade de São Paulo (IFUSP)（圣保罗大学物理研究所）；Unidade Acadêmica de Física da Universidade Federal de Campina Grande (UAF-UFCG)（坎皮纳格兰德联邦大学物理学术单元）；Departamento de Engenharias e Exatas, Universidade Federal do Paraná (UFPR)（巴拉那联邦大学工程与精确科学系）；Programa de pós-graduação em Física & Departamento de Física, Universidade Estadual de Londrina (UEL)（隆德里纳州立大学物理研究生项目与物理系）；Programa de Pós-Graduação em Física e Astronomia, Universidade Tecnológica Federal do Paraná (UTFPR)（巴拉那联邦技术大学物理与天文学研究生项目）；Programa de Pós-Graduação em Física Aplicada, Universidade Federal da Integração Latino-Americana（拉丁美洲融合联邦大学应用物理研究生项目）；Departamento de Física, Universidade Federal do Espírito Santo, Núcleo de Astrofísica e Cosmologia (Cosmo-Ufes)（圣埃斯皮里图联邦大学物理系，天体物理学与宇宙学中心）
Using idealized models of the accretion disk, we investigate the effects induced by the modified theories of gravity on the annihilation of the neutrino pair annihilation into electron-positron pairs ($ν{\bar ν}\to e^-e^+$), occurring near the rotational axis. For the accretion disk, we have considered the models with temperature $T=constant$ and $T\propto r^{-1}$. In both cases, we find that the modified theories of gravity lead to an enhancement, up to more than one order of magnitude with respect to General Relativity, of the rate of the energy deposition rate of neutrino pair annihilation.
Many modern simulations of accretion disks use moment-based methods for radiation transport to determine the thermal evolution of the disk and the properties of the ejected matter. The popular M1 scheme evolves the rank-0 and rank-1 moments requires an analytic approximation for the rank-2 and higher tensors. We present the open-source Monte Carlo steady-state general-relativistic neutrino transport code SedonuGR, which we use to asses fundamental analytic closure assumptions, quantify proposed closure errors, and test an extension of the MEFD closure to the rank-3 moment. We demonstrate that …
Quintessence fields, introduced to explain the speed-up of the Universe, might affect the geometry of spacetime surrounding black holes, as compared to the standard Schwarzschild and Kerr geometries. In this framework, we study the neutrino pairs annihilation into electron-positron pairs ($ν{\bar ν}\to e^-e^+$) near the surface of a neutron star, focusing, in particular, on the Schwarzschild-like geometry in presence of quintessence fields. The effect of the latter is to increase the minimum photon-sphere radius ($R_{ph}$), increasing in such a way the maximum energy deposition rate near to $R…
Aim: To study the multimessenger nature of the signal that can result from the phase transition of a neutron star to a quark star and their corresponding astrophysical observations. Methods: The phase transition process is initiated by the abrupt pressure and density changes at the star center, giving rise to a shock which deconfines matter followed by a weak front converting excess down to strange quarks to attain absolute stability. This process's effects are investigated by understanding how the energy escapes from the star in the form of neutrino-antineutrino annihilation. For such annihil…
The study of neutrino pair annihilation into electron-positron pairs ($ν{\bar ν}\to e^-e^+$) is astrophysically well-motivated because it is a possible powering mechanism for the gamma-ray bursts (GRBs). In this paper, we estimate the gamma-ray energy deposition rate (EDR) arising from the annihilation of the neutrino pairs in the equatorial plane of a slowly rotating black hole geometry modified by the broken Lorentz symmetry (induced by a background bumblebee vector field). More specifically, owing to the presence of a dimensionless Lorentz symmetry breaking (LSB) parameter $l$ arising from …
We present our studies on the neutrino pairs annihilation into electron-positron pairs ($ν{\bar ν}\to e^-e^+$) near the surface of a neutron star in the framework of extended theories of gravity. The latter modifies the maximum energy deposition rate near to the photonsphere and it might be several orders of magnitude greater than that computed in the framework of General Relativity. These results provide a rising in the Gamma-Ray Bursts energy emitted from a close binary neutron star system and might be a fingerprint of modified theories of gravity, changing our view of astrophysical phenomen…
We analyze neutrino ($ν$) emission channels in energetic ($\gtrsim 10^{52}$ erg) long gamma-ray bursts within the binary-driven hypernova model. The binary-driven hypernova progenitor is a binary system composed of a carbon-oxygen star and a neutron star (NS) companion. The gravitational collapse leads to a type Ic supernova (SN) explosion and triggers an accretion process onto the NS. For orbital periods of a few minutes, the NS reaches the critical mass and forms a black hole (BH). Two physical situations produce MeV $ν$s. First, during the accretion, the NS surface emits $ν$-$\barν$ pairs b…
In the binary-driven hypernova model of long gamma-ray bursts, a carbon-oxygen star explodes as a supernova in presence of a neutron star binary companion in close orbit. Hypercritical (i.e. highly super-Eddington) accretion of the ejecta matter onto the neutron star sets in, making it reach the critical mass with consequent formation of a Kerr black hole. We have recently shown that, during the accretion process onto the neutron star, fast neutrino flavour oscillations occur. Numerical simulations of the above system show that a part of the ejecta keeps bound to the newborn Kerr black hole, l…
