Distribution of Spectral Lags in Gamma‐Ray Bursts

Chen, L.; Lou, Yu‐Qing; Wu, Meng-He; Qu, J. L.; Jia, S.; Yang, Xuejuan

doi:10.1086/426774

Cited by 54 publications

(52 citation statements)

References 30 publications

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“…Negative lags, which violate the typical hardsoft evolution of GRBs, have been observed in a small minority of cases (e.g. Chen et al 2005) and may be more prevalent in short bursts (Gupta et al 2002;Yi et al 2006). A long tail extending to ∼5 s is observed in the lag distribution in Fig.…”

Section: Spectral Lags Of Integral Grbsmentioning

confidence: 84%

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Global characteristics of GRBs observed with INTEGRAL and the inferred large population of low-luminosity GRBs

Foley

McGlynn

Hanlon

et al. 2008

A&A

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Context. INTEGRAL has two sensitive gamma-ray instruments that have detected and localised 47 gamma-ray bursts (GRBs) from its launch in October 2002 up to July 2007. Aims. We present the spectral, spatial, and temporal properties of the bursts in the INTEGRAL GRB catalogue using data from the imager, IBIS, and spectrometer, SPI. Methods. Spectral properties of the GRBs are determined using power-law and, where appropriate, Band model and quasithermal model fits to the prompt emission. Spectral lags, i.e. the time delay in the arrival of low-energy γ-rays with respect to high-energy γ-rays, are measured for 31 of the GRBs. Results. The photon index distribution of power-law fits to the prompt emission spectra is presented and is consistent with that obtained by Swift. The peak flux distribution shows that INTEGRAL detects proportionally more weak GRBs than Swift because of its higher sensitivity in a smaller field of view. The all-sky rate of GRBs above ∼0.15 ph cm −2 s −1 is ∼1400 yr −1 in the fully coded field of view of IBIS. Two groups are identified in the spectral lag distribution of INTEGRAL GRBs, one with short lags <0.75 s (between 25−50 keV and 50−300 keV) and one with long lags >0.75 s. Most of the long-lag GRBs are inferred to have low redshifts because of their long spectral lags, their tendency to have low peak energies, and their faint optical and X-ray afterglows. They are mainly observed in the direction of the supergalactic plane with a quadrupole moment of Q = −0.225 ± 0.090 and hence reflect the local large-scale structure of the Universe. Conclusions. The spectral, spatial, and temporal properties of the 47 GRBs in the INTEGRAL catalogue are presented and compared with the results from other missions. The rate of long-lag GRBs with inferred low luminosity is ∼25% of type Ib/c supernovae. Some of these bursts could be produced by the collapse of a massive star without a supernova. Alternatively, they could result from a different progenitor, such as the merger of two white dwarfs or a white dwarf with a neutron star or black hole, possibly in the cluster environment without a host galaxy.

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Section: Spectral Lags Of Integral Grbsmentioning

confidence: 84%

“…Spectral lag evolution is often seen in multi-peaked GRBs (e.g. Hakkila & Giblin 2004;Chen et al 2005;Ryde et al 2005;Hakkila et al 2008), and poses obvious difficulties for the use of the lag as a luminosity indicator.…”

Section: Spectral Lags Of Integral Grbsmentioning

confidence: 99%

Global characteristics of GRBs observed with INTEGRAL and the inferred large population of low-luminosity GRBs

Foley

McGlynn

Hanlon

et al. 2008

A&A

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“…Recently, from an independent analysis of distinct timescales, suggested that LGRBs occur at greater distances from the central engine while SGRBs at smaller distances, i.e., two distinct γ-ray emission regions may result in two different properties of GRBs, including the varieties of pulse profiles, as mentioned above. They also pointed out the fact that LGRBs usually have a long positive spectral lag (e.g., Norris et al 2000;Daigne & Mochkovitch 2003;Chen et al 2005) and SGRBs have negligible lag (Norris & Bonnell 2006;Zhang et al 2006). This can be explained under the assumption that the curvature effect is a main contributor to the spectral lag (Ryde 2005;Shen et al 2005).…”

Section: Discussionmentioning

confidence: 99%

An analysis of the durations of Swift gamma-ray bursts

Zhang

Choi²

2008

A&A

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Context. Swift detectors are found to be more sensitive to long-soft bursts than pre-Swift missions. This may largely bias the distribution of durations and thus classification of gamma-ray bursts. Aims. We systematically investigate the duration distribution of gamma-ray bursts in the Swift era vs. that of pre-Swift bursts. Methods. For the purpose of this study, statistical methods such as the K-S test and linear/non-linear fitting analysis have been used to examine the duration properties of Swift bursts in both observer and source frames. Results. For 95 GRBs with known redshift, we show that two log-normal distributions of duration are clearly divided at T 90 2 s. The intrinsic durations also show a bimodal distribution but shift systematically toward the smaller value and the distribution exhibits a narrower width than the observed one. Swift long bursts exhibit a wider duration dynamic range in both observer and source frames in comparison to pre-Swift long bursts. Conclusions. We find that Swift bursts and pre-Swift ones can share the same criterion of classification in terms of duration at 2 s, although both monitors have large differences with respect to sensitivity of a given energy band.

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“…Most of the previous work on spectral lags has been based on observations with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (Tsutsui et al 2008;Hakkila et al 2008Hakkila et al , 2007Chen et al 2005;Band et al 2004; Salmonson & Galama 2002;Norris 2002;Band 1997). The launch of the Swift satellite (Gehrels et al 2004) ushered in a new era of GRB research.…”

Section: Introductionmentioning

confidence: 99%

SPECTRAL LAGS AND THE LAG-LUMINOSITY RELATION: AN INVESTIGATION WITHSWIFTBAT GAMMA-RAY BURSTS

Ukwatta

Stamatikos

Dhuga

et al. 2010

ApJ

121

137

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Spectral lag, the time difference between the arrival of high-energy and low-energy photons, is a common feature in gamma-ray bursts (GRBs). Norris et al. reported a correlation between the spectral lag and the isotropic peak luminosity of GRBs based on a limited sample. More recently, a number of authors have provided further support for this correlation using arbitrary energy bands of various instruments. In this paper, we report on a systematic extraction of spectral lags based on the largest Swift sample to date of 31 GRBs with measured redshifts. We extracted the spectral lags for all combinations of the standard Swift hard X-ray energy bands: 15-25 keV, 25-50 keV, 50-100 keV, and 100-200 keV and plotted the time dilation corrected lag as a function of isotropic peak luminosity. The mean value of the correlation coefficient for various channel combinations is −0.68 with a chance probability of ∼0.7 × 10 −3 . In addition, the mean value of the power-law index is 1.4 ± 0.3. Hence, our study lends support to the existence of a lag-luminosity correlation, albeit with large scatter.

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Distribution of Spectral Lags in Gamma‐Ray Bursts

Cited by 54 publications

References 30 publications

Global characteristics of GRBs observed with INTEGRAL and the inferred large population of low-luminosity GRBs

Global characteristics of GRBs observed with INTEGRAL and the inferred large population of low-luminosity GRBs

An analysis of the durations of Swift gamma-ray bursts

SPECTRAL LAGS AND THE LAG-LUMINOSITY RELATION: AN INVESTIGATION WITHSWIFTBAT GAMMA-RAY BURSTS

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