scholarly journals 35 Years of Ground-Based Gamma-ray Astronomy

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 432
Author(s):  
Paula Chadwick
Keyword(s):  
Gamma Ray ◽  
Technical Expertise ◽  
Personal Account ◽  
Gamma Ray Astronomy ◽  
History Of ◽  
The Universe

This paper provides a brief, personal account of the development of ground-based gamma-ray astronomy, primarily over the last 35 years, with some digressions into the earlier history of the field. Ideas related to the imaging of Cherenkov events and the potential for the use of arrays were in existence for some time before the technical expertise required for their exploitation emerged. There has been occasional controversy, great creativity and some heroic determination—all of it part of establishing a new window into the universe.

Gamma-Ray Bursts as Probes of the Universe

2011 ◽  
Author(s):  
Joshua S. Bloom
Keyword(s):  
Star Formation ◽  
Cosmic Rays ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Ongoing Study ◽  
Observable Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact about GRBs that makes them such great probes is that they are fantastically bright and so can be seen to the farthest reaches of the observable Universe. In parallel with the ongoing study of GRB events and progenitors, new lines of inquiry have burgeoned: using GRBs as unique probes of the Universe in ways that are almost completely divorced from the nature of GRBs themselves. Topics discussed include studies of gas, dust, and galaxies; the history of star formation; measuring reionization and the first objects in the universe; neutrinos, gravitational waves, and cosmic rays; quantum gravity and the expansion of the universe; and the future of GRBs.

scholarly journals The Unsolved Problem of Stellar Origins

1996 ◽  
Vol 169 ◽  
pp. 533-549
Author(s):  
Charles J. Lada
Keyword(s):  
Twentieth Century ◽  
Science Fiction ◽  
High Energy Physics ◽  
Gamma Ray ◽  
High Energy ◽  
Giant Molecular Clouds ◽  
Observational Astronomy ◽  
History Of ◽  
Large Telescopes ◽  
The Universe

We now stand at the threshold of the 21st century having witnessed perhaps the greatest era of astronomical discovery in the history of mankind. During the twentieth century the subject of astronomy was revolutionized and completely transformed by technology and physics. Advances in technology that produced radio astronomy, infrared astronomy, UV, X and γ ray astronomy, large telescopes on the ground, in balloons, aircraft and space coupled with advances in nuclear, atomic and high energy physics forever changed the way in which the universe is viewed. Indeed, it is altogether likely that future historians of science will consider the twentieth century as the Golden Age of observational astronomy. As a measure of how far we have come in the last 100 years, recall that at the turn of this century the nature of spiral nebulae and of the Milky Way itself as an island universe were not yet revealed. The expansion of the universe and the microwave background were not yet discovered and exotic objects such as quasars, pulsars, gamma-ray bursters and black holes were not even envisioned by the most imaginative authors of science fiction. The interstellar medium, with its giant molecular clouds, magnetic fields and obscuring dust was unknown. Not even the nature of stars, these most fundamental objects of the astronomical universe, was understood.

scholarly journals A gamma-ray determination of the Universe’s star formation history

Science ◽  
2018 ◽  
Vol 362 (6418) ◽  
pp. 1031-1034 ◽  
Author(s):  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Cosmic Time ◽  
Star Formation History ◽  
Large Area ◽  
Extragalactic Background Light ◽  
Galaxy Surveys ◽  
Formation History ◽  
History Of ◽  
The Universe

The light emitted by all galaxies over the history of the Universe produces the extragalactic background light (EBL) at ultraviolet, optical, and infrared wavelengths. The EBL is a source of opacity for gamma rays via photon-photon interactions, leaving an imprint in the spectra of distant gamma-ray sources. We measured this attenuation using 739 active galaxies and one gamma-ray burst detected by the Fermi Large Area Telescope. This allowed us to reconstruct the evolution of the EBL and determine the star formation history of the Universe over 90% of cosmic time. Our star formation history is consistent with independent measurements from galaxy surveys, peaking at redshiftz~ 2. Upper limits of the EBL at the epoch of reionization suggest a turnover in the abundance of faint galaxies atz~ 6.

Introductory remarks

1994 ◽  
Vol 346 (1678) ◽  
pp. 1-2 ◽  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Neutrino Flux ◽  
The Sun ◽  
Gamma Ray Astronomy ◽  
The Past ◽  
The Subject ◽  
Neutrino Astronomy ◽  
The Universe ◽  
Particle Physicist

Nearly twenty years ago, G. D. Rochester and I organized a Discussion Meeting here on the origin of the cosmic radiation. P art of that meeting was devoted to primary gamma rays, and this meeting was followed a few years later by a meeting devoted entirely to gamma ray astronomy. At that time gamma rays represented a ‘new window on the Universe’. Now it is the turn of neutrinos to move into that slot, although it must be said that neutrino astronomy is not as far on as gamma ray astronomy was at that stage. Nevertheless, the subject has started and has already thrown up some dramatic questions, questions of interest to both astronomer and elementary particle physicist. In the more conventional astronomies, the Sun appears to be quite well behaved, and reasonably understood, with the interests of many centring on more distant and ‘dramatic’ objects, such as supernovae and extragalactic sources. With neutrinos, however, supernovae seem to be well behaved — at the superficial level, at least and based on one event — but the Sun does not. The remarkable deficit in solar neutrino flux recorded by Davis and collaborators over the past decades has been confirmed and we look forward to hearing the details of these confirmations, as well as the energy dependence of the flux and its comparison with expectation.

scholarly journals The Prospects for Very High Energy Gamma Ray Astronomy

1995 ◽  
Vol 48 (2) ◽  
pp. 305 ◽  
Author(s):  
T Kifune
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Coming Of Age ◽  
High Energy ◽  
Detection Techniques ◽  
Gamma Ray Astronomy ◽  
Very High Energy ◽  
Energy Gamma ◽  
The Universe ◽  
Very High

Very-high-energy (VHE) gamma rays, with energies .<: 1 TeV = 1012 eV, are observed with ground-based telescopes using the atmospheric Cerenkov technique. This field of astronomy has recently experienced its coming of age, opening a new observational window on the universe after efforts spanning almost 30 years. Recent advances in this field have been aided by the results from satellite detectors with high-energy (HE) gamma ray 'eyes'. Satellite detectors are sensitive to HE gamma rays, up to energies of about 10 GeV = 1010 eV. In this paper, VHE gamma ray astronomy is reviewed, and the 3�8 m diameter telescope of the Japanese-Australian CANGAROO project is used to illustrate the detection techniques. As VHE gamma ray astronomy is closely related to observations in the HE region, results from recent satellite experiments are also discussed.

scholarly journals Observations of GRBs at high redshift

2007 ◽  
Vol 365 (1854) ◽  
pp. 1377-1384 ◽  
Author(s):  
Nial R Tanvir ◽  
Páll Jakobsson
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Gamma Ray Bursts ◽  
Star Formation History ◽  
Redshift Distribution ◽  
Formation History ◽  
History Of ◽  
The Universe

The extreme luminosity of gamma-ray bursts and their afterglows means they are detectable, in principle, to very high redshifts. Although the redshift distribution of gamma-ray bursts (GRBs) is difficult to determine, due to incompleteness of present samples, we argue that for Swift-detected bursts, the median redshift is between 2.5 and 3, with a few per cent probably at z >6. Thus, GRBs are potentially powerful probes of the era of reionization and the sources responsible for it. Moreover, it seems probable that they can provide constraints on the star-formation history of the Universe and may also help in the determination of the cosmological parameters.

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