We present a suite of the first 3D GRMHD collapsar simulations, which extend from the selfconsistent jet launching by an accreting Kerr black hole (BH) to the breakout from the star. We identify three types of outflows, depending on the angular momentum, l, of the collapsing material and the magnetic field, B, on the BH horizon: (i) subrelativistic outflow (low l and high B), (ii) stationary accretion shock instability (SASI; high l and low B), (iii) relativistic jets (high l and high B). In the absence of jets, freefall of the stellar envelope provides a good estimate for the BH accretion rate. Jets can substantially suppress the accretion rate, and their duration can be limited by the magnetization profile in the star. We find that progenitors with large (steep) inner density powerlaw indices (≳ 2), face extreme challenges as gammaray burst (GRB) progenitors due to excessive luminosity, global time evolution in the light curve throughout the burst and short breakout times, inconsistent with observations. Our results suggest that the wide variety of observed explosion appearances (supernova/supernova + GRB/lowluminosity GRBs) and the characteristics of the emitting relativistic outflows (luminosity and duration) can be naturally explained by the differences in the progenitor structure.more »
Gravitational lensing near a black hole is strong enough that light rays can circle the event horizon multiple times. Photons emitted in multiple directions at a single event, perhaps because of localized, impulsive heating of accreting plasma, take multiple paths to a distant observer. In the Kerr geometry, each path is associated with a distinct light travel time and a distinct arrival location in the image plane, producing black hole glimmer. This sequence of arrival times and locations uniquely encodes the mass and spin of the black hole and can be understood in terms of properties of bound photon orbits. We provide a geometrically motivated treatment of Kerr glimmer and evaluate it numerically for simple hotspot models to show that glimmer can be measured in a finiteresolution observation. We discuss potential measurement methods and implications for tests of the Kerr hypothesis.
 Award ID(s):
 1716327
 Publication Date:
 NSFPAR ID:
 10361711
 Journal Name:
 The Astrophysical Journal
 Volume:
 909
 Issue:
 2
 Page Range or eLocationID:
 Article No. 217
 ISSN:
 0004637X
 Publisher:
 DOI PREFIX: 10.3847
 Sponsoring Org:
 National Science Foundation
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ABSTRACT 
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