Gamma-ray bursts (GRBs) are the most energetic explosions in the Universe, thus providing a unique laboratory for the study of extreme astrophysical processes. In parallel, their large luminosity makes GRBs a premier probe of the early Universe. My thesis has explored and exploited both aspects of GRB science by addressing the following fundamental open questions: 1) what is the nature of the GRB ejecta?, 2) how does the GRB progenitor population evolve with redshift, and 3) how can GRBs be used to probe the high-redshift Universe? To answer these questions, I present the first multi-wavelength detection and modeling of a GRB reverse shock, a comprehensive analysis of the plateau phase of GRB light curves, studies of the evolution of the progenitor population to redshifts, z~9, and demonstrate the use of GRBs as probes of galaxy formation and evolution through the first galaxy mass-metallicity relation at z~3-5. I find support for baryonic ejecta in GRB~130427A, evidence that GRB jets contain a large amount of energy in slow-moving ejecta, and proof that the GRB progenitor population does not evolve to the highest redshifts at which it has yet been observed. Building on the decade of observations by the Swift GRB mission, future observations and modeling of GRBs and their host galaxies will provide clues to these and other open questions in GRB science, allowing for the first statistical studies of their progenitors and host environments to the epoch of reionization and beyond.

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.

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

Summarizes the current understanding of Astronomical gamma-ray bursts, short-lived flashes of high-energy radiation, which have eluded even a basic explanation for over twenty years, and describes directions for future research.

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 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.

Gamma-ray bursts are the most violent events since the birth of the universe. They are about ten times more energetic than the most powerful supernovae. At their peak, gamma-ray bursts are the brightest objects in space, about 100,000 times brighter than an entire galaxy. And yet until recently these titanic eruptions were the most mysterious events in astronomy. In The Biggest Bangs, astrophysicist Jonathan Katz offers a fascinating account of the scientific quest to unravel the mystery of these incredible phenomena. With an eye for colorful detail and a talent for translating scientific jargon into plain English, Katz ranges from the accidental discovery of gamma-ray bursts (by a Cold War satellite system monitoring the Nuclear Test Ban Treaty) to the frustrating but ultimately successful efforts to localize these bursts in distant galaxies. He describes the theories, the equipment (the most recent breakthrough was made with a telescope you could carry under your arm), and the pioneers who have finally begun to explain these strange bursts. And along the way, he offers important lessons about science itself, arguing that "small science" is as valuable as institutionalized "big science," that observations are more the product of advances in technology than of theory, and that theory is only "the concentrated essence of experiment." With the advent of the space age a mere 40 years ago, we have grown used to strangeness in the universe--and confident in science's ability to explain it. In The Biggest Bangs, Jonathan Katz shows that there are still wonders out there that exceed the bounds of our imagination and defy our ability to understand them.

continues to be extremely rewarding. Experiments on future missions, such as the two 1981 Veneras, Gamma Ray Observatory, and the International Solar Polar Mission, will undoubtedly provide new and unexpected discoveries, but the work of the Leningrad group is likely to remain an important contribution to the field for some time to come. c.E.S.R. KEVIN HURLEY Toulouse, France June 9, 1981 CATALOG OF COSMIC GAMMA-RAY BURSTS FROM THE KONUS EXPERIMENT DATA Parts I and II E. P. MAZETS, S. V. GOLENETSKII, V. N. IL'INSKII, V. N. PANOV, R. L. APTEKAR, YU. A. GUR'YAN, M. P. PROSKURA, 1. A. SOKOLOV, Z. Y A. SOKOLOV A, and T. V. KHARITONOV A A. F. Ioffe Physical-Technical Institute, U.S.S.R. Academy of Sciences, Leningrad, U.S.S.R. and A. V. DYATCHKOV and N. G. KHAVENSON Institute of Cosmic Research, U.S.S.R. Academy of Sciences, Moscow, U.S.S.R. (Received 2 July, 1980) Abstract. Data are presented on the temporal structure, fluxes, energy spectra and coordinates of the sources of gamma-ray bursts detected in the KONUS experiment on Venera 1 I and Venera 12 space probes in the period September 1978 to May 1979. The statistical distributions of gamma bursts in duration, intensity, and peak power, as well as the distribution of the burst sources over the celestial sphere presented are based on the updated KONUS information obtained until February 1980.

Impressively, gamma-ray bursts (GRBs) release the same amount of energy in a mere matter of seconds as the sun does in its lifetime. Gamma-ray Burst Correlations presents an overview of the observational correlations; their physical interpretations; their use as redshift estimators; and their potential use as cosmological tools. The author describes the existing correlations as well as breaching the possible meaning and controversy behind the results, and the applicability of several GRB correlations as model discriminators and cosmological indicators. A description of selection bias and the attempts made so far in order to use them as standard candles can help scientists to find the key to solve this puzzling problem. Covering an ever-expanding topic, this book will reach a wide audience, including students and researchers within the astronomical community.