Neutrino Cooled Disk and Its Stability

Norita Kawanaka; Shin Mineshige

doi:10.1086/517985

paper

Neutrino Cooled Disk and Its Stability

arXiv:astro-ph/0702630 · doi:10.1086/517985

Abstract

We investigate the structure and stability of hypercritical accretion flows around stellar-mass black holes, taking into account neutrino cooling, lepton conservation, and firstly a realistic equation of state in order to properly treat the dissociation of nuclei. We obtain the radial distributions of physical properties, such as density, temperature and electron fraction, for various mass accretion rates $0.1 \sim 10 M_{⊙} s^{- 1}$ . We find that, depending on mass accretion rates, different physics affect considerably the structure of the disk; most important physics is (1) the photodissociation of nuclei around $r \sim 100 r_{g}$ for relatively low mass accretion rates ( $M ˙ \sim 0.01 - 0.1 M_{⊙} s^{- 1}$ ), (2) efficient neutrino cooling around $r \sim 10 - 100 r_{g}$ for moderately high mass accretion rate ( $M ˙ \sim 0.2 - 1.0 M_{⊙} s^{- 1}$ ), and (3) neutrino trapping ( $r \sim 3 - 10 r_{g}$ ) for very high mass accretion rate ( $M ˙ ≳ 2.0 M_{⊙} s^{- 1}$ ). We also investigate the stability of hypercritical accretion flows by drawing the thermal equilibrium curves, and find that efficient neutrino cooling makes the accretion flows rather stable against both thermal and viscous modes.

26 pages, 28 figures, Accepted for publication in ApJ

Neutrino Cooled Disk and Its Stability

Abstract

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