Pair‐Instability Supernovae, Gravity Waves, and Gamma‐Ray Transients

Abstract

Growing evidence suggests that the Ðrst generation of stars may have been quite massive (D100È300 If they retain their high mass until death, such stars will, after about 3 Myr, make pair-instability M _ ). supernovae. Models for these explosions have been discussed in the literature for four decades, but very few included the e †ects of rotation and none employed a realistic model for neutrino trapping and transport. Both turn out to be very important, especially for those stars whose cores collapse into black holes (helium cores above about 133We consider the complete evolution of two zero-metallicity stars of M _ ). 250 and 300Despite their large masses, we argue that the low metallicities of these stars imply M _ . negligible mass loss. Evolving the stars with no mass loss, but including angular momentum transport and rotationally induced mixing, the two stars produce helium cores of 130 and 180Products of M _ . central helium burning (e.g., primary nitrogen) are mixed into the hydrogen envelope with dramatic e †ects on the radius, especially in the case of the 300 model. Explosive oxygen and silicon burning M _ cause the 130 helium core (250 star) to explode, but explosive burning is unable to drive an M _ M _ explosion in the 180 helium core, and it collapses to a black hole. For this star, the calculated M _ angular momentum in the presupernova model is sufficient to delay black hole formation, and the star initially forms an D50 1000 km core within which neutrinos are trapped. The calculated growth M _ , time for secular rotational instabilities in this core is shorter than the black hole formation time, and they may develop. If so, the estimated gravitational wave energy and wave amplitude are E GW B 10~3 c2 and but these estimates are very rough and depend sensitively on the nonlin-M _ h`B 10~21/d(Gpc), ear nature of the instabilities. After the black hole forms, accretion continues through a disk. The mass of the disk depends on the adopted viscosity but may be quite large, up to 30 when the black hole M _ mass is 140The accretion rate through the disk can be as large as 1È10 s~1. Although the disk M _ .M _ is far too large and cool to transport energy efficiently to the rotational axis by neutrino annihilation, it has ample potential energy to produce a 1054 erg jet driven by magnetic Ðelds. The interaction of this jet with surrounding circumstellar gas may produce an energetic gamma-ray transient, but given the probable redshift and the consequent timescale and spectrum, this model may have difficulty explaining typical gamma-ray bursts.

A VLA Study of High-redshift GRBs. I. Multiwavelength Observations and Modeling of GRB 140311A

“…The large luminosities of GRB afterglows make these energetic events premier probes of the high-redshift universe, ranging from the parsec-scale environments of the progenitors to the properties of the intergalactic medium (Totani et al 2006;Inoue et al 2007;Tanvir et al 2009;Wang et al 2012;Chornock et al 2013Chornock et al , 2014. Additionally, high-redshift GRBs have been speculated to possibly differ from lower redshift events in their energy scales, durations, and circumburst media (Fryer et al 2001;Bromm et al 2003;Heger et al 2003;Suwa & Ioka 2011;Toma et al 2011). Due to time dilation, high-redshift GRBs also afford an opportunity to capture rapidly evolving reverse shock emission, and thereby a means of probing the Lorentz factor and composition of the relativistic ejecta powering the afterglow (Piran 2005;Mészáros 2006;Laskar et al 2013Laskar et al , 2014Laskar et al , 2016Perley et al 2014;Alexander et al 2017).…”

Stellar Collapse and Gravitational Waves

“…during collapse peaks off center, as is indicated by some simulations of collapsing Population III stars (Fryer, Woosley, & Heger 2001).…”

“…The Centrella & McMillan paper is specialized to smooth particle hydrodynamics (SPH). Fryer & Warren (2002) have recently modeled core collapse with a 3-dimensional code using SPH. One of the goals of this work will be to test whether the instabilities discussed above, particularly bar modes and fragmentation, actually occur in a computational stellar collapse model.…”

“…This code includes all of the physics used in 2-dimensional models less than a decade ago (e.g. Herant et al Isosurfaces of upward moving bubbles (radial velocities moving outward at 1000 km/sec) as a function of time (tA < tB < tC < tD) from the 3-dimensional simulations of Fryer & Warren (2002). Note that the number of modes decreases slightly as the flows merge over time (compare panel A with later panels).…”

“…These simulations assumed spherically symmetric implementation of gravity for better comparison with past 2-dimensional work. However, the code developed by Fryer & Warren (2002) has a tree-based algorithm for calculating gravity and can be used to model the collapse of rotating or asymmetric cores. The first rotating models are running and, as predicted by the 2-dimensional simulations (Fryer & Heger 2000), show convection that is primarily limited to the polar regions (Fig.…”