DISCERNING THE PHYSICAL ORIGINS OF COSMOLOGICAL GAMMA-RAY BURSTS BASED ON MULTIPLE OBSERVATIONAL CRITERIA: THE CASES OF z = 6.7 GRB 080913, z = 8.2 GRB 090423, AND SOME SHORT/HARD GRBs

By Bing Zhang, Binbin Zhang, F. Virgili, E. Liang, D. A. Kann, Xuefeng Wu, D. Proga, Houjun Lv, K. Toma, P. Mészáros and 3 more. 2009

278 citations recorded by the source corpus.

The two high-redshift gamma-ray bursts, GRB 080913 at z = 6.7 and GRB 090423 at z = 8.2, recently detected by Swift appear as intrinsically short, hard GRBs. They could have been recognized by BATSE as short/hard GRBs should they have occurred at z ⩽ 1. In order to address their physical origin, we perform a more thorough investigation on two physically distinct types (Type I/II) of cosmological GRBs and their observational characteristics. We reiterate the definitions of Type I/II GRBs and then review the following observational criteria and their physical motivations: supernova (SN) association, specific star-forming rate (SFR) of the host galaxy, location offset, duration, hardness, spectral lag, statistical correlations, energetics and collimation, afterglow properties, redshift distribution, luminosity function, and gravitational wave signature. Contrary to the traditional approach of assigning the physical category based on the gamma-ray properties (duration, hardness, and spectral lag), we take an alternative approach to define the Type I and Type II Gold Samples using several criteria that are more directly related to the GRB progenitors (SN association, host galaxy type, and specific SFR). We then study the properties of the two Gold Samples and compare them with the traditional long/soft and short/hard samples. We find that the Type II Gold Sample reasonably tracks the long/soft population, although it includes several intrinsically short (shorter than 1 s in the rest frame) GRBs. The Type I Gold Sample only has five GRBs, four of which are not strictly short but have extended emission. Other short/hard GRBs detected in the Swift era represent the BATSE short/hard sample well, but it is unclear whether all of them belong to Type I. We suggest that some (probably even most) high-luminosity short/hard GRBs instead belong to Type II. Based on multiple observational criteria, we suggest that GRB 080913 and GRB 090423 are more likely Type II events. In general, we acknowledge that it is not always straightforward to discern the physical categories of GRBs, and re-emphasize the importance of invoking multiple observational criteria. We cautiously propose an operational procedure to infer the physical origin of a given GRB with available multiple observational criteria, with various caveats laid out.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3f8084dcf7ec06696690ecbcea4fd6fad279c7cf

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In Astronomy and Astrophysics

1. Bing Zhang
2. Pawan Kumar
3. E. Berger
4. E. Nakar
5. E. Liang
6. B. Metzger
7. Binbin Zhang
8. T. Piran

Citations in the corpus

• A COMPREHENSIVE ANALYSIS OF FERMI GAMMA-RAY BURST DATA. I. SPECTRAL COMPONENTS AND THE POSSIBLE PHYSICAL ORIGINS OF LAT/GBM GRBs (2010, methodology): “This is consistent with the finding (Zhang et al. 2009; Ghirlanda et al. 2009) that long/short GRBs are not clearly distinguished in the Lpγ,iso − Ep domain.”
• SHORT VERSUS LONG AND COLLAPSARS VERSUS NON-COLLAPSARS: A QUANTITATIVE CLASSIFICATION OF GAMMA-RAY BURSTS (2012, background): “Zhang et al. (2009) suggested to classify individual GRBs using various subsets of properties, e.g., spectral lag, peak energy, etc.”
• Short-Duration Gamma-Ray Bursts (2013, background): “…such as red hift, supernova association, host galaxy type and star formation rate, burst offset relative to the host galaxy, the density profile of the circumburst medium, theγ-ray and afterglow energy scale, and a combination of prompte ission properties (see Figure 8 of Zhang et al. 2009).”
• The unusual X-ray emission of the short Swift GRB 090515: evidence for the formation of a magnetar? (2010, background): “Zhang et al. (2009) suggested that the burst duration, observed by BAT, represents the duration that the jet is relativistic and, with a nonrelativistic (or less relativistic) jet, the central engine can be active for longer than this time and may be observed by XRT.”
• The physics of gamma-ray bursts & relativistic jets (2014, methodology): “One way is to correlate Lγ,p,iso with τ/(1 + z)× (1 + z)0.33 = τ/(1 + z)0.67 (Gehrels et al., 2006; Zhang et al., 2009a).”
• THE MILLISECOND MAGNETAR CENTRAL ENGINE IN SHORT GRBs (2015, background): “It has been found that short GRBs typically have a large offset from their host galaxies (Fong et al. 2010; Fong & Berger 2013; Berger 2014), so that the local ISM density may be much lower than that of long GRBs (e.g. Fan et al. 2005; Zhang et al. 2009; Kann et al. 2011).”