Black Hole Disk Accretion in Supernovae

Abstract

Massive stars in a certain mass range may form low-mass black holes after supernova explosions. In such massive stars, fallback of D0.1 materials onto a black hole is expected because of a deep gravi-M _ tational potential or a reverse shock propagating back from the outer composition interface. We study hydrodynamical disk accretion onto a newborn low-mass black hole in a supernova using the smoothed particle hydrodynamics method. If the progenitor was rotating before the explosion, the fallback material should have a certain amount of angular momentum with respect to the black hole, thus forming an accretion disk. The disk material will eventually accrete toward the central object because of viscosity at a supercritical accretion rate, for the Ðrst several tens of days. (Here, is the Edding-M 0 /M 0 crit [ 106, M 0 crit ton luminosity divided by c2.) We then expect that such an accretion disk is optically thick and advection dominated ; that is, the disk is so hot that the produced energy and photons are advected inward rather than being radiated away. Thus, the disk luminosity is much less than the Eddington luminosity. The disk becomes hot and dense ; for for example,being the viscosity parameter) in the vicinity of the black hole. Depend-103(a vis /0.01)~1 a vis ing on the material mixing, some interesting nucleosynthesis processes via rapid proton and alphaparticle captures are expected even for reasonable viscosity magnitudes and some of them (a vis D 0.01), could be ejected in a disk wind or a jet without being swallowed by the black hole.

On the Nature of Part-Time Radio Pulsars

“…This seems to be in contradiction with our scenario since thermal, soft radiation is not expected from a propeller, in which nonthermal magnetospheric emission should dominate (e.g., Popov et al 2006). From the work of Cannizzo et al (1990) and Mineshige et al (1997) for supernova fallback, we can roughly estimate the mass inflow rate in the disk as for RRAT J1819Ϫ1458, which is much smaller than the measured luminosity ∼10 33 ergs s Ϫ1 , implying that neutron star cooling could still dominate X-ray emission in this object. But we mention that a neutron star undergoing propeller spin-down could be a weak point source of g-ray radiation during the (radio-)quiescent state (Wang & Robertson 1985).…”

Hypercritical Advection-Dominated Accretion Flow

“…Boundary conditions on the neutron star are, therefore, not much different from those on a black hole, since in either case the accreting energy is taken away rapidly without back reaction on the system. We thus find our results to be very close to those of Mineshige et al (1997) for black hole disc accretion, once we scale our accretion rate down to the ∼Ṁ/Ṁ Edd ∼ 10 6 that they use. …”

“…This means that the inner boundary condition for the flow will no longer be much different between neutron stars and black holes in this regime, even during the time the neutron star exists (before dropping into a black hole). Mineshige et al (1997) studied hydrodynamical disc accretion onto a newborn low-mass black hole in a supernova using the smoothed particle hydrodynamics method. In one of the two cases they begin with the envelope in rotation.…”

Disks Surviving the Radiation Pressure of Radio Pulsars

“…It is a possibility that some of the ejected matter fails to achieve the escape velocity and falls back (Woosley et al 2002). As the progenitor is rotating, the fallback matter might have enough angular momentum to settle into a disk (Mineshige et al 1997). The idea of fallback disks around pulsars dates back to Michel & Dessler (1981).…”