The Swift satellite and redshifts of long gamma-ray bursts

Abstract

Until 6 October 2005 sixteen redshifts have been measured of long gamma-ray bursts discovered by the Swift satellite. Further 45 redshifts have been measured of the long gamma-ray bursts discovered by other satellites. Here we perform five statistical tests comparing the redshift distributions of these two samples assuming - as the null hypothesis - identical distribution for the two samples. Three tests (Student's $t$-test, Mann-Whitney test, Kolmogorov-Smirnov test) reject the null hypothesis on the significance levels between 97.19 and 98.55%. Two different comparisons of the medians show extreme $(99.78-99.99994)$% significance levels of rejection. This means that the redshifts of the Swift sample and the redshifts of the non-Swift sample are distributed differently - in the Swift sample the redshifts are on average larger. This statistical result suggests that the long GRBs should on average be at the higher redshifts of the Swift sample.

4 pages, accepted as an A&A Research Note

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Cited by in corpus (22)

• The Afterglows of Swift-era Gamma-Ray Bursts. I. Comparing pre-Swift and Swift era Long/Soft (Type II) GRB Optical Afterglows
• Jet breaks and Energetics of Swift GRB X-ray Afterglows
• The GRB 060218/SN 2006aj event in the context of other Gamma-Ray Burst Supernovae
• On the Redshift Distribution of Gamma Ray Bursts in the Swift Era
• Detailed Classification of Swift's Gamma-Ray Bursts
• Search for Gravitational Waves Associated with 39 Gamma-Ray Bursts Using Data from the Second, Third, and Fourth LIGO Runs
• Classification of Swift's gamma-ray bursts
• An analysis of the durations of Swift Gamma-Ray Bursts
• Statistical Study of Observed and Intrinsic Durations among BATSE and Swift/BAT GRBs
• MultiPulse {\it Fermi} Gamma-Ray Bursts. I. Evidence of the Transition from Fireball to Poynting-flux-dominated Outflow
• A comparison of the gamma-ray bursts detected by BATSE and Swift
• A distinct peak-flux distribution of the third class of gamma-ray bursts: A possible signature of X-ray flashes?
• The duration distribution of Swift Gamma-Ray Bursts
• Synchrotron emission in GRBs observed by Fermi: Its limitations and the role of the photosphere
• Population synthesis of gamma-ray bursts with precursor activity and the spinar paradigm
• Cosmological effects on the observed flux and fluence distributions of gamma-ray bursts: Are the most distant bursts in general the faintest ones?
• Spectro-polarimetric analysis of prompt emission of GRB 160325A: jet with evolving environment of internal shocks
• Does the GRB Duration Depend on Redshift?
• Resolving the Excess of Long GRBs at low redshift in the Swift Era
• A Quark-Nova in the wake of a core-collapse Supernova: a unifying model for long duration Gamma-Ray Bursts and Fast Radio Bursts
• Studying the variability of the X-ray spectral parameters of high-redshift GRBs' afterglows
• Fermi-GBM Observations of GRB 210812A: Signatures of a Million Solar Mass Gravitational Lens