Gamma-ray bursts: Maybe not so old after all (original) (raw)
On the search for the origin of short gamma-ray bursts
Advances in Space Research, 2007
Gamma-ray bursts appear to be the most powerful explosions in the universe. Two types exist-long ones, which last for tens or hundreds of seconds, and short ones that last a few milliseconds to a second. There is a sufficient research evidence to show that long bursts are the death throes of massive stars in distant, young, and vigorously star forming galaxies, while the origin of the short gammaray bursts has been shrouded in mystery until now. In December 2005, the first study that accurately pinpoints a short gamma-ray bursts to an old galaxy, implying that a population of old neutron stars are the sources of these explosions was released. The advent of NASA's Swift Satellite and the rapid follow up by the ground based telescopes will no doubt help to localize the short gamma-ray bursts which are fainter than the long bursts.
New Evidence for the Cosmological Origin of Gamma-Ray Bursts
The Astrophysical Journal, 1996
We compare the burst distribution of the new (2B) BATSE catalogue to a cosmological distribution. We nd that the distribution is insensitive to cosmological parameters such as and and to the width of the bursts luminosity function. The maximal red shift of the long bursts is 2:1 (assuming no evolution) while z max (long) of the short bursts is signi cantly lower z max (short) 0:5. In agreement with this relatively nearby origin of the short burst we nd an indication that these bursts are correlated ( 2 level at 10 ) with Abell clusters. This is the rst known correlation of the bursts with any other astrophysical population and if con rmed by further observations it will provides additional evidence for the cosmological origin of those bursts.
GAMMA-RAY BURSTERS AND THE EMERGENCE OF LIFE
Abstract A few times a day, intense bursts of gamma rays are detected randomly and uniformly from the distant Universe. These gamma ray bursters are now believed to represent the final explosion of a massive star to form a black hole, and are so energetic that we detect them from as far away as the edge of the observable Universe. This amount of energy is also enough to sterilise all life-bearing planets within a few thousand light years.
On Recent Developments in Theoretical and Experimental General Relativity, Gravitation and Relativistic Field Theories (In 3 Volumes), 2002
Cosmic γ-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean γ-ray energies after the beaming corrections are ∼ 10 51 erg. Bursts are associated with faint ( R ∼ 25 mag) galaxies at cosmological redshifts, with z ∼ 1. The host galaxies span a range of luminosities and morphologies, but appear to be broadly typical for the normal, actively star-forming galaxy populations at comparable redshifts and magnitudes. Some of the challenges for the future include: the nature of the short bursts and possibly other types of bursts and transients; use of GRBs to probe the obscured star formation in the universe, and possibly as probes of the very early universe; and their detection as sources of high-energy particles and gravitational waves.
Gamma-Ray Burst Progenitors Confront Observations
The Tenth Marcel Grossmann Meeting, 2006
The discovery of a supernova emerging at late times in the afterglow of GRB 030329 has apparently settled the issue on the nature of the progenitor of gamma-ray bursts. We now know that at least a fraction of cosmological GRBs are associated with the death of massive stars, and that the two explosions are most likely simultaneous. Even though the association was already suggested for GRB 980425, the peculiarity of that burst did not allow to extend the association to all GRBs. The issue is now to understand whether GRB 030329 is a "standard burst" or not. I will discuss some peculiarities of GRB 030329 and its afterglow lightcurve showing how, rather than a classical cosmological GRB, it looks more like a transition object linking weak events like GRB 980425 to the classical long duration GRBs. I will also discuss the problems faced by the Hypernova scenario to account for the X-ray features detected in several GRBs and their afterglows.
A Solution to the gamma-Ray Burst Mystery?
1998
Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed γ rays along the flow direction. Repeated excitation/decay of highly relativistic baryonic ejecta from merger or accretion induced collapse of neutron stars in dense stellar regions (DSRs), like galactic cores, globular clusters and super star-clusters, can convert enough kinetic energy in such events in distant galaxies into cosmological gamma ray bursts (GRBs). The model predicts remarkably well all the main observed temporal and spectral properties of GRBs. Its success strongly suggests that GRBs are γ ray tomography pictures of DSRs in galaxies at cosmological distances with unprecedented resolution: A time resolution of dt ∼ 1 ms in a GRB can resolve stars at a Hubble distance which are separated by only D ∼ 10 10 cm. This is equivalent to the resolving power of an optical telescope with a diameter larger than one Astronomical Unit!
Light from the Cosmic Frontier: Gamma-Ray Bursts
2013
Gamma-Ray Bursts (GRBs) are the most powerful cosmic explosions since the Big Bang, and thus act as signposts throughout the distant Universe. Over the last 2 decades, these ultra-luminous cosmological explosions have been transformed from a mere curiosity to essential tools for the study of high-redshift stars and galaxies, early structure formation and the evolution of chemical elements. In the future, GRBs will likely provide a powerful probe of the epoch of reionisation of the Universe, constrain the properties of the first generation of stars, and play an important role in the revolution of multi-messenger astronomy by associating neutrinos or gravitational wave (GW) signals with GRBs. Here, we describe the next steps needed to advance the GRB field, as well as the potential of GRBs for studying the Early Universe and their role in the up-coming multi-messenger revolution.
Understanding the engines and progenitors of gamma-ray bursts
The European Physical Journal A, 2019
Our understanding of the engines and progenitors of gamma-ray bursts has expanded through the ages as a broader set of diagnostics has allowed us to test our understanding of these objects. Here we review the history of the growth in our understanding, focusing on 3 leading engines and 9 potential progenitors. The first gravitational wave detection of a short burst is the latest in a series of breakthrough observations shaping this understanding and we study the importance of multi-diagnostic, multi-messenger observations on these engines and their progenitors. Our understanding based on a detailed study of nearby bursts can be applied to make predictions for the trends expected as we begin to observe high redshift bursts and we discuss these trends. PACS. 95.85.Pw gamma-ray-95.85.Sz gravitational radiation, magnetic fields, and other observations 2 Observations and Models in the first 3 decades With the discovery of GRBs, astrophysicists began to design missions focused on finding more. The Burst And Transient Source Experiment (BATSE) [Fishman et al., 1993] produced a large database of gamma-ray bursts, allowing astrophysicists to discern different GRB subgroups: short, hard bursts and long, soft bursts [Mazets et al., 1983, Kouveliotou et al., 1993]. The short bursts had durations from a few milliseconds to a few seconds. The
A glimpse of the end of the dark ages: the gamma-ray burst of 23 April 2009 at redshift 8.3
Nature, 2009
It is thought that the first generations of massive stars in the Universe were an important, and quite possibly dominant, source of the ultra-violet radiation that reionized the hydrogen gas in the intergalactic medium (IGM); a state in which it has remained to the present day. Measurements of cosmic microwave background anisotropies suggest that this phase-change largely took place in the redshift range z=10.8 +/- 1.4, while observations of quasars and Lyman-alpha galaxies have shown that the process was essentially completed by z=6. However, the detailed history of reionization, and characteristics of the stars and proto-galaxies that drove it, remain unknown. Further progress in understanding requires direct observations of the sources of ultra-violet radiation in the era of reionization, and mapping the evolution of the neutral hydrogen fraction through time. The detection of galaxies at such redshifts is highly challenging, due to their intrinsic faintness and high luminosity distance, whilst bright quasars appear to be rare beyond z~7. Here we report the discovery of a gamma-ray burst, GRB 090423, at redshift z=8.26 -0.08 +0.07. This is well beyond the redshift of the most distant spectroscopically confirmed galaxy (z=6.96) and quasar (z=6.43). It establishes that massive stars were being produced, and dying as GRBs, ~625 million years after the Big Bang. In addition, the accurate position of the burst pinpoints the location of the most distant galaxy known to date. Larger samples of GRBs beyond z~7 will constrain the evolving rate of star formation in the early universe, while rapid spectroscopy of their afterglows will allow direct exploration of the progress of reionization with cosmic time.