Relativistic Global Solutions of Neutrino-Dominated Accretion Flows

Abstract

Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes are plausible candidates for the central engines of gamma-ray bursts (GRBs). We investigate one-dimensional global solutions of NDAFs, taking account of general relativity in Kerr metric, neutrino physics and nucleosynthesis more precisely than previous works. We calculate sixteen solutions with different characterized accretion rates and black hole spins to exhibit the radial distributions of various physical properties in NDAFs. We confirm that the electron degeneracy has important effects in NDAFs and we find that the electron fraction is about 0.46 in the outer region for all the sixteen solutions. From the perspective of the mass fraction, free nucleons, 4 He, and 56 Fe dominate in the inner, middle, and outer region, respectively. The influence of neutrino trapping on the annihilation is of importance for the superhigh accretion (Ṁ = 10M ⊙ s −1 ) and most of the sixteen solutions have an adequate annihilation luminosity for GRBs.

Central Engine of Late-Time X-Ray Flares With Internal Origin

“…Such a flow is named as the neutrino-dominated accretion flow (NDAF). The structure and radiation of an NDAF has been extensively studied (e.g., Popham et al (1999); Di Matteo et al (2002); Gu et al (2006); Kawanaka & Mineshige (2007); Liu et al (2007Liu et al ( , 2013Liu et al ( , 2014; Lei et al (2009) ;Zalamea & Beloborodov (2011); Pan & Yuan (2012); Janiuk et al (2013); Xue et al (2013); Cao et al (2014). In the hyper-accretion scenario, the relativistic jet may be powered by the following two mechanisms.…”

Vertical Convection in Neutrino-Dominated Accretion Flows

“…Neutrino radiation is the main cooling mechanism, possibly having the ability to power GRBs via neutrino annihilation outside of the disk. In past decades much work has been done onthis model, all of which can be divided into the following categories: (i) research on the stable or timedependent radial characteristics of the disk, such as the dynamics, structure, components, and luminosity of the NDAF model (see, e.g., Popham et al 1999;Narayan et al 2001;Di Matteo et al 2002;Kohri & Mineshige 2002;Janiuk et al 2004Janiuk et al , 2007Kohri et al 2005;Lee et al 2005;Gu et al 2006;Chen & Beloborodov 2007;Kawanaka & Mineshige 2007;Liu et al 2007;Kawabata et al 2008;Zhang & Dai 2009;Kawanaka et al 2013;Li & Liu 2013;Xue et al 2013) or the magnetic NDAF model (e.g., Lei et al 2009;Janiuk & Yuan 2010;Luo et al 2013); (ii) corresponding applications to GRBs observations (e.g., Reynoso et al 2006;Lei et al 2007;Lazzati et al 2008;Liu et al 2010bLiu et al , 2012bRomero et al 2010;Kawanaka & Kohri 2012;Sun et al 2012;Hou et al 2014aHou et al , 2014b; (iii) research on the vertical characteristics of the model and the application of these characteristics to observations (e.g., Sawyer 2003;Liu et al 2008Liu et al , 2010aLiu et al , 2012aLiu et al , 2013Liu et al , 2014…”

Neutrino-dominated accretion flows as the central engine of gamma-ray bursts

“…The steady radial structure and neutrino luminosity of BH NDAFs are most widely studied (see e.g, Popham et al 1999;Narayan et al 2001;Di Matteo et al 2002;Kohri & Mineshige 2002;Kohri et al 2005;Lee et al 2005;Gu et al 2006;Chen & Beloborodov 2007;Liu et al 2007;Janiuk et al 2007;Rossi et al 2008;Janiuk & Yuan 2010;Kawanaka & Mineshige 2007;Kawanaka et al 2013b;Li & Liu 2013;Luo & Yuan 2013;Xue et al 2013). After the first work of Popham et al (1999), Di Matteo et al (2002) recalculated the NDAF radial structure by taking into account neutrino opacity with Newtonian potential.…”

“…As most detailed study of NDAFs, Xue et al (2013) investigated the relativistic one-dimensional (1D) steady global solutions of NDAFs by taking into account detailed neutrino physics, balance of chemical potentials, photodisintegration, and nuclear statistical equilibrium. This is mainly introduced below.…”