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Studies of high-redshift gamma-ray bursts (GRBs) provide important information about the early Universe such as the rates of stellar collapsars and mergers, the metallicity content, constraints on the re-ionization period, and probes of the…

High Energy Astrophysical Phenomena · Physics 2016-03-23 T. N. Ukwatta , P. R. Wozniak , N. Gehrels

Gamma-ray bursts (GRBs) are intense, short-lived bursts of gamma-ray radiation observed up to a high redshift ($z \sim 10$) due to their luminosities. Thus, they can serve as cosmological tools to probe the early Universe. However, we need…

Being able to quickly select among gamma-ray bursts (GRBs) seen by the Swift satellite those which are high-z candidates would give ground-based observers a better chance to determine a redshift for such distant GRBs. Information about…

High Energy Astrophysical Phenomena · Physics 2009-06-25 T. N. Ukwatta , T. Sakamoto , K. S. Dhuga , W. C. Parke , S. D. Barthelmy , N. Gehrels , M. Stamatikos , J. Tueller

Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Here we introduce…

Gamma-ray bursts (GRBs) are among the most luminous explosions in the Universe and serve as powerful probes of the early cosmos. However, the rapid fading of their afterglows and the scarcity of spectroscopic measurements make photometric…

The long gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-20 Amy Lien , Takanori Sakamoto , Neil Gehrels , David M. Palmer , Scott D. Barthelmy , Carlo Graziani , John K. Cannizzo

To draw inferences about gamma-ray burst (GRB) source populations based on Swift observations, it is essential to understand the detection efficiency of the Swift burst alert telescope (BAT). This study considers the problem of modeling the…

High Energy Astrophysical Phenomena · Physics 2016-02-10 Philip B Graff , Amy Y Lien , John G Baker , Takanori Sakamoto

The gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early universe.…

High Energy Astrophysical Phenomena · Physics 2016-03-25 Amy Lien , Takanori Sakamoto , Neil Gehrels , David M. Palmer , Scott D. Barthelmy , Carlo Graziani , John K. Cannizzo

Gamma-Ray Bursts (GRBs), due to their high luminosities are detected up to redshift 10, and thus have the potential to be vital cosmological probes of early processes in the universe. Fulfilling this potential requires a large sample of…

Gamma-ray bursts (GRBs) can be probes of the early universe, but currently, only 26% of GRBs observed by the Neil Gehrels Swift Observatory GRBs have known redshifts ($z$) due to observational limitations. To address this, we estimated the…

The Swift spacecraft detects and autonomously observes ~100 Gamma Ray Bursts (GRBs) per year, ~96% of which are detected by the X-ray telescope (XRT). GRBs are accompanied by optical transients and the field of ground-based follow-up of…

Astrophysics · Physics 2007-11-06 P. A. Evans , L. G. Tyler , A. P. Beardmore , J. P. Osborne

We employ realistic constraints on astrophysical and instrumental selection effects to model the Gamma-Ray Burst (GRB) redshift distribution using {\it Swift} triggered redshift samples acquired from optical afterglows (OA) and the TOUGH…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 David Coward , Eric Howell , Marica Branchesi , Giulia Strata , Dafne Guetta , Bruce Gendre , Damien Macpherson

The majority of Swift gamma-ray bursts (GRBs) observed at z > 6 have prompt durations of T90 < 30s, which, at first sight, is surprising given that cosmological time-dilation means this corresponds to < 5s in their rest frames. We have…

High Energy Astrophysical Phenomena · Physics 2015-06-17 O. M. Littlejohns , N. R. Tanvir , R. Willingale , P. A. Evans , P. T. O'Brien , A. J. Levan

Gamma Ray Bursts (GRBs) are a powerful probe of the high redshift Universe. We present a tool to estimate the detection rate of high-z GRBs by a generic detector with defined energy band and sensitivity. We base this on a population model…

We compute the probability to detect long Gamma Ray Bursts (GRBs) at z>5 with Swift, assuming that GRBs form preferentially in low-metallicity environments. The model fits well both the observed BATSE and Swift GRB differential peak flux…

Astrophysics · Physics 2009-11-13 R. Salvaterra , S. Campana , G. Chincarini , G. Tagliaferri , S. Covino

Context. Gamma-ray bursts (GRBs), observed at redshifts as high as 9.4, could serve as valuable probes for investigating the distant Universe. However, this necessitates an increase in the number of GRBs with determined redshifts, as…

A good fraction of GRBs detected by Swift are at a large redshift (up to z=6.3, so far). Their study allows us to investigate, among other things, the cosmic star formation in the early Universe (possibly up to the re-ionization era) and…

Astrophysics · Physics 2008-11-26 S. Campana , G. Tagliaferri , D. Malesani , L. Stella , P. D'Avanzo , G. Chincarini , S. Covino

Detecting high-z GRBs is important for constraining the GRB formation rate, and tracing the history of re-ionization and metallicity of the universe. Based on the current sample of GRBs detected by Swift with known redshifts, we…

Astrophysics · Physics 2009-06-23 T. N. Ukwatta , T. Sakamoto , M. Stamatikos , N. Gehrels , K. S. Dhuga

Future detection of high-redshift gamma-ray bursts (GRBs) will be an important tool for studying the early Universe. Fast and accurate redshift estimation for detected GRBs is key for encouraging rapid follow-up observations by ground- and…

Gamma-ray bursts (GRBs) are spectacularly energetic events, with the potential to inform on the early universe and its evolution, once their redshifts are known. Unfortunately, determining redshifts is a painstaking procedure requiring…

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