A COMPREHENSIVE ANALYSIS OFFERMIGAMMA-RAY BURST DATA. II.EpEVOLUTION PATTERNS AND IMPLICATIONS FOR THE OBSERVED SPECTRUM-LUMINOSITY RELATIONS

Lü, Rui; Wei, Jun-Jie; Liang, Enxiang; Zhang, Bin-Bin; Lu, H.; Lü, Lian Zhong; Lei, Wei‐Hua; Zhang, Bing

doi:10.1088/0004-637x/756/2/112

Cited by 148 publications

(170 citation statements)

References 77 publications

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“…This is supported by a number of correlations in which E p,i is involved: its correlation with E iso (Amati et al 2002), its time-resolved analogue (Golenetskii et al 1983;Yonetoku et al 2004;Ghirlanda et al 2011;Lu et al 2012;Frontera et al 2012), with the collimationcorrected energy E γ (Ghirlanda et al 2004) for long GRBs, and both E iso and the energy released in the X-ray band, E X,iso , in the three-parameter correlation, which holds for both long and short GRBs (Bernardini et al 2012;Margutti et al 2013). Thus, investigating the connection between E p,i and temporal properties can provide clues on the physics of the prompt emission.…”

Section: Discussionmentioning

confidence: 94%

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

Dichiara

Guidorzi

Amati

et al. 2016

A&A

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Context. The origin of the gamma-ray burst (GRB) prompt emission still defies explanation, in spite of recent progress made, for example, on the occasional presence of a thermal component in the spectrum along with the ubiquitous non-thermal component that is modelled with a Band function. The combination of finite duration and aperiodic modulations make GRBs hard to characterise temporally. Although correlations between GRB luminosity and spectral hardness on one side and time variability on the other side have long been known, the loose and often arbitrary definition of the latter makes the interpretation uncertain. Aims. We characterise the temporal variability in an objective way and search for a connection with rest-frame spectral properties for a number of well-observed GRBs. Methods. We studied the individual power density spectra (PDS) of 123 long GRBs with measured redshift, rest-frame peak energy E p,i of the time-averaged ν F ν spectrum, and well-constrained PDS slope α detected with Swift, Fermi and past spacecraft. The PDS were modelled with a power law either with or without a break adopting a Bayesian Markov chain Monte Carlo technique. Results. We find a highly significant E p,i -α anti-correlation. The null hypothesis probability is ∼10 −9 . Conclusions. In the framework of the internal shock synchrotron model, the E p,i -α anti-correlation can hardly be reconciled with the predicted E p,i ∝ Γ −2 , unless either variable microphysical parameters of the shocks or continual electron acceleration are assumed. Alternatively, in the context of models based on magnetic reconnection, the PDS slope and E p,i are linked to the ejecta magnetisation at the dissipation site, so that more magnetised outflows would produce more variable GRB light curves at short timescales ( 1 s), shallower PDS, and higher values of E p,i .

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Section: Discussionmentioning

confidence: 94%

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

Dichiara

Guidorzi

Amati

et al. 2016

A&A

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“…The observation of an E pi -E iso relation in time-resolved spectra (e.g. Ghirlanda et al 2010;Frontera et al 2012;Basak & Rao 2012;Lu et al 2012) may also provide insights into the origin of the E pi -E iso boundary. Finally, Since the E pi -E iso relation is not an intrinsic property of GRBs, it may be difficult to use it to standardize GRBs (Ghirlanda et al 2006;Mészáros & Gehrels 2012).…”

Section: Discussionmentioning

confidence: 99%

TheE_peak–E_isorelation revisited withFermiGRBs

Heussaff

Atteia

Zolnierowski

2013

A&A

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Aims. We used a sample of gamma-ray bursts (GRBs) detected by Fermi and Swift to reanalyze the correlation discovered by Amati et al. (2002, A&A, 390, 81) between E pi , the peak energy of the prompt GRB emission, and E iso , the energy released by the GRB assuming isotropic emission. This correlation has been disputed by various authors, and our aim is to assess whether it is an intrinsic GRB property or the consequence of selection effects. Methods. We constructed a sample of Fermi GRBs with homogeneous selection criteria, and we studied their distribution in the E pi -E iso plane. Our sample is made of 43 GRBs with a redshift and 243 GRBs without a redshift. We show that GRBs with a redshift follow a broad E pi -E iso relation, while GRBs without a redshift show several outliers. We use these samples to discuss the impact of selection effects associated with GRB detection and with redshift measurement. Results. We find that the E pi -E iso relation is partly due to intrinsic GRB properties and partly due to selection effects. The lower right boundary of the E pi -E iso relation stems from a true lack of luminous GRBs with low E pi . In contrast, the upper left boundary is attributed to selection effects acting against the detection GRBs with low E iso and large E pi that appear to have a lower signal-to-noise ratio. In addition, we demonstrate that GRBs with and without a redshift follow different distributions in the E pi -E iso plane. GRBs with a redshift are concentrated near the lower right boundary of the E pi -E iso relation. This suggests that it is easier to measure the redshift of GRBs close to the lower E pi -E iso boundary and that GRBs with a redshift follow the Amati relation better than the general population. In this context, we attribute the controversy about the reality of the Amati relation to the complex nature of this relation resulting from the combination of a true physical boundary and biases favoring the detection and the measurement of the redshift of GRBs located close to this boundary.

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“…In case of GRBs with multiple but separable pulses, it is frequently observed that the first pulse shows a HTS evolution, followed by a jump in the peak energy during the onset of a second pulse, and then again showing a HTS evolution in the falling part of that pulse (see e.g., Lu et al 2012). A very similar behaviour is seen for GRB 151006A, though the presence of a second pulse is not seen in the lightcurve.…”

Section: Evidence For a Second Hard Pulsementioning

confidence: 74%

“…Several studies conducted for GRBs with single/separable pulses show definite evolution of the spectral peak (E p ), either hard to soft (HTS) or intensity tracking (IT) (Liang & Kargatis 1996;Kaneko et al 2006;Lu et al 2012;Basak & Rao 2014). However, for GRBs with overlapping pulses, this picture is complicated which is probably affected by pulse overlap (e.g., Hakkila & Preece 2014).…”

Section: Introductionmentioning

confidence: 99%

Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

Basak

Iyyani

Chand

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of GRB 151006A, the first GRB detected by Astrosat CZT Imager (CZTI). We study the long term spectral evolution by exploiting the capabilities of Fermi and Swift satellites at different phases, which is complemented by the polarization measurement with the CZTI. While the light curve of the GRB in different energy bands show a simple pulse profile, the spectrum shows an unusual evolution. The first phase exhibits a hard-to-soft (HTS) evolution until ∼ 16 − 20 s, followed by a sudden increase in the spectral peak reaching a few MeV. Such a dramatic change in the spectral evolution in case of a single pulse burst is reported for the first time. This is captured by all models we used namely, Band function, Blackbody+Band and two blackbodies+power law. Interestingly, the Fermi Large Area Telescope (LAT) also detects its first photon (> 100 MeV) during this time. This new injection of energy may be associated with either the beginning of afterglow phase, or a second hard pulse of the prompt emission itself which, however, is not seen in the otherwise smooth pulse profile. By constructing Bayesian blocks and studying the hardness evolution we find a good evidence for a second hard pulse. The Swift data at late epochs (> T 90 of the GRB) also shows a significant spectral evolution consistent with the early second phase. The CZTI data (100-350 keV), though having low significance (1σ), show high values of polarization in the two epochs (77% to 94%), in agreement with our interpretation.

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A COMPREHENSIVE ANALYSIS OFFERMIGAMMA-RAY BURST DATA. II.E_pEVOLUTION PATTERNS AND IMPLICATIONS FOR THE OBSERVED SPECTRUM-LUMINOSITY RELATIONS

Cited by 148 publications

References 77 publications

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

TheE_peak–E_isorelation revisited withFermiGRBs

Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

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A COMPREHENSIVE ANALYSIS OFFERMIGAMMA-RAY BURST DATA. II.EpEVOLUTION PATTERNS AND IMPLICATIONS FOR THE OBSERVED SPECTRUM-LUMINOSITY RELATIONS

Cited by 148 publications

References 77 publications

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

TheEpeak–Eisorelation revisited withFermiGRBs

Surprise in simplicity: an unusual spectral evolution of a single pulse GRB 151006A

Contact Info

Product

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A COMPREHENSIVE ANALYSIS OFFERMIGAMMA-RAY BURST DATA. II.E_pEVOLUTION PATTERNS AND IMPLICATIONS FOR THE OBSERVED SPECTRUM-LUMINOSITY RELATIONS

TheE_peak–E_isorelation revisited withFermiGRBs