The observational diversity of ''gamma-ray bursts'' (GRBs) has been increasing, and the natural inclination is a proliferation of models. We explore the possibility that at least part of this diversity is a consequence of a single basic model for the central engine operating in a massive star of variable mass, differential rotation rate, and mass loss rate. Whatever that central engine may be--and here the collapsar is used as a reference point--it must be capable of generating both a narrowly collimated, highly relativistic jet to make the GRB, and a wide angle, sub-relativistic outflow responsible for exploding the star and making the supernova bright. To some extent, the two components may vary independently, so it is possible to produce a variety of jet energies and supernova luminosities. We explore, in particular, the production of low energy bursts and find a lower limit, (almost equal to) 1048 erg s−1 to the power required for a jet to escape a massive star before that star either explodes or is accreted. Lower energy bursts and ''suffocated'' bursts may be particularly prevalent when the metallicity is high, i.e., in the modern universe at low redshift.

The thermonuclear model for x- and .gamma.-ray bursts is discussed. Different regimes of nuclear burning are reviewed, each appropriate to a given range of (steady state) accretion rate. Accretion rates in the range 10−14 to 10−8 Msub solar y−1 all appear capable of producing x-ray transients of various durations and intervals. Modifications introduced by radiatively driven mass loss, the thermal inertia of the envelope, different burning mechanisms, and two-dimensional considerations are discussed as are difficulties encountered when the thermonuclear model is confronted with observations of rapidly recurrent bursts (less than or equal to 10 min), and super-Eddington luminosities and temperatures. Results from a numerical simulation of a combined hydrogen-helium runaway initiated at pycnonuclear density are presented for the first time. The thermonuclear model for .gamma.-ray bursts is also reviewed and updated, particularly with regard to the breakdown of the steady state hypothesis employed in previous work. Solely on the basis of nuclear instability, .gamma.-ray bursts of various types appear possible for a very broad variety of accretion rates (approx. 10−17 to approx. 10−11 Msub solar y−1) although other considerations may restrict this range. The thermonuclear model appears capable of yielding a great diversity of high energy transient phenomena for various accretion rates, magnetic field configurations, and neutron star envelope histories.

A complete text on the physics of gamma-ray bursts, the most brilliant explosions since the Big Bang.

The various possibilities for the origin ("progenitors") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset distribution appears to be inconsistent with the coalescing neutron star binary hypothesis (and, similarly, black-hole--neutron star coalescences); instead, the distribution is statistically consistent with a population of progenitors that closely traces the ultra-violet light of galaxies. This is naturally explained by bursts which originate from the collapse of massive stars ``collapsars''). This claim is further supported by the unambiguous detections of intermediate-time (approximately three weeks after the bursts) emission ``bumps'' which appear substantially more red than the afterglows themselves. I claim that these bumps could originate from supernovae that occur at approximately the same time as the associated GRB; if true, GRB 980326 and GRB 011121 provide strong observational evidence connecting cosmological GRBs to high-redshift supernovae and implicate massive stars as the progenitors of at least some long-duration GRBs.

For over a quarter of a century, gamma-ray bursts were the outstanding mystery in astronomy. No one knew where they were or how they worked. The Biggest Bangs tells how the mystery was unraveled, from the discovery of gamma-ray bursts by a Cold War satellite system monitoring the Nuclear TestBan Treaty to the localization of bursts in distant galaxies and the observation of surprisingly bright flashes of light from the bursts themselves. The Biggest Bangs is for laymen with an interest in science, physicists and astronomers interested in subjects in those fields not their specialty,students in non-technical astonomy courses, and as supplemental reading for courses in the history of science.

This book summarizes the science to be carried out by the upcoming Cherenkov Telescope Array, a major ground-based gamma-ray observatory that will be constructed over the next six to eight years. The major scientific themes, as well as core program of key science projects, have been developed by the CTA Consortium, a collaboration of scientists from many institutions worldwide.CTA will be the major facility in high-energy and very high-energy photon astronomy over the next decade and beyond. CTA will have capabilities well beyond past and present observatories. Thus, CTA's science program is expected to be rich and broad and will complement other major multiwavelength and multimessenger facilities. This book is intended to be the primary resource for the science case for CTA and it thus will be of great interest to the broader physics and astronomy communities. The electronic version (e-book) is available in open access.

Nuclear astrophysics as it stands today is a fascinating science. Even though, compared to other scientific fields, it is a young discipline which has developed only in this century, it has answered many questions concerning the under standing of our cosmos. One of these great achievements was the concept of nucleosynthesis, the creation of the elements in the early universe in interstellar matter and in stars. Nuclear astrophysics has continued, to solve many riddles of the evolution of the myriads of stars in our cosmos. This review volume attempts to provide an overview of the current status of nuclear astrophysics. Special emphasis is given to the interdisciplinary nature of the field: astronomy, nuclear physics, astrophysics and particle physics are equally involved. One basic effort of nuclear astrophysics is the collection of ob servational facts with astronomical methods. Laboratory studies of the nuclear processes involved in various astrophysical scenarios have provided fundamen tal information serving both as input for and test of astrophysical models. The theoretical understanding of nuclear reaction mechanisms is necessary, for example, to extrapolate the experimentally determined reaction rates to the thermonuclear energy range, which is relevant for the nuclear processes in our cosmos. Astrophysical models and calculations allow us to simulate how nuclear processes contribute to driving the evolution of stars, interstellar matter and the whole universe. Finally, elementary particle physics also plays an important role in the field of nuclear astrophysics, for instance through weak interaction processes involving neutrinos.

Since their discovery was first announced in 1973, gamma-ray bursts (GRBs) have been among the most fascination objects in the universe. While the initial mystery has gone, the fascination continues, sustained by the close connection linking GRBs with some of the most fundamental topics in modern astrophysics and cosmology. Both authors have been active in GRB observations for over two decades and have produced an outstanding account on both the history and the perspectives of GRB research.