On Spectral Peak Energy of Swift Gamma-Ray Bursts

Abstract

Owing to narrow energy band of \textit{Swift}/BAT, several urgent issues are required to pay more attentions but unsolved so far. We systematically study the properties of a refined sample of 283 \textit{Swift}/BAT gamma-ray bursts with well-measured spectral peak energy ($E_{\text{p}}$) at a high confidence level larger than 3$\sigma$. It is interestingly found that duration ($T_{90}$) distribution of \textit{Swift} bursts still exhibits an evident bimodality with a more reliable boundary of $T_{90}\simeq$1.06 s instead of 2 s for previously contaminated samples including bursts without well-peaked spectra, which is very close to $\sim$1.27 s and $\sim$0.8 s suggested by some authors for Fermi/GBM and \textit{Swift}/BAT catalogs, respectively. The \textit{Swift}/BAT short and long bursts have comparable mean $E_{\text{p}}$ values of $87_{-49}^{+112}$ and $85_{-46}^{+101}$ keV in each, similar to what found for both types of BATSE bursts, which manifests the traditional short-hard/long-soft scheme may not be tenable for the certain energy window of a detector. In statistics, we also investigate the consistency of distinct methods for the $E_{\text{p}}$ estimates and find that Bayesian approach and BAND function can always give consistent evaluations. In contrast, the frequently-used cut-off power-law model matches two other methods for lower $E_{\text{p}}$ and will overestimate the $E_{\text{p}}$ more than 70\% as $E_{\text{p}}>$100 keV. Peak energies of X-ray flashes, X-ray rich bursts and classical gamma-ray bursts could have an evolutionary consequence from thermal-dominated to non-thermal-dominated radiation mechanisms. Finally, we find that the $E_{\text{p}}$ and the observed fluence ($S_{\gamma }$) in the observer frame are correlated as $E_p\simeq [S_{\gamma }/(10^{-5}ergc{m}^{-2}){]}^{0.28}\times 117.5_{-32.4}^{+44.7}$ keV proposed to be an useful indicator of GRB peak energies.

25 pages; 7 figures; 2 tables. Accepted for publication in ApJ

References in corpus (14)

• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Gamma-Ray Bursts: Progress, Problems & Prospects
• Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
• A Complete Catalog of Swift GRB Spectra and Durations: Demise of a Physical Origin for Pre-Swift High-Energy Correlations
• The First Swift BAT Gamma-Ray Burst Catalog
• An analysis of the durations of Swift Gamma-Ray Bursts
• Statistical Study of Observed and Intrinsic Durations among BATSE and Swift/BAT GRBs
• Spectral evolution in gamma-ray bursts: predictions of the internal shock model and comparison to observations
• Gaussian-mixture-model-based cluster analysis of gamma-ray bursts in the BATSE catalog
• Revisiting the characteristics of the spectral lags in short gamma-ray bursts
• A New Discriminator for Gamma-Ray Burst Classification: The Epeak-Fluence Energy Ratio
• Multivariate analysis of BATSE gamma-ray burst properties using skewed distributions
• Inferring the emission regions for different kinds of gamma-ray bursts
• Systematic study of the peak energy of the broad-band Gamma-Ray Burst

Cited by in corpus (13)

• A Comparative Study of Luminosity Functions and Event Rate Densities of Long GRBs with Non-parametric Method
• An analytic derivation of the empirical correlations of gamma-ray bursts
• Properties of Gamma-Ray Bursts Associated with Supernovae and Kilonovae
• Revealing nature of GRB 210205A, ZTF21aaeyldq (AT2021any), and follow-up observations with the 4K$\times$4K CCD Imager+3.6m DOT
• Gamma-Ray Bursts with Extended Emission: Classifications, Energy Correlations and Radiation Properties
• Prompt emission and early optical afterglow of VHE detected GRB 201015A and GRB 201216C: onset of the external forward shock
• Prevalence of Extra Power-Law Spectral Components in Short Gamma-Ray Bursts
• GRB 201015A and the nature of low-luminosity soft gamma-ray bursts
• The Statistical Similarity of Repeating and Non-Repeating Fast Radio Bursts
• New evidence of multiple channels for the origin of gamma-ray bursts with extended emission
• Overall Spectral Properties of Prompt Emissions with Diverse Segments in Swift/BAT Short Gamma-ray Bursts
• Detection of Low-Redshift Excess in Supernova-Linked Gamma-Ray Bursts
• Tale of GRB 171010A/SN 2017htp and GRB 171205A/SN 2017iuk: Magnetar origin?