Correlation between the isotropic energy and the peak energy at zero fluence for the individual pulses of GRBs: towards an universal physical correlation for the prompt emission

Abstract

We find a strong correlation between the peak energy at zero fluence (${\mathrm{E}}_{\mathrm{peak},0}$) and the isotropic energy (${\mathrm{E}}_{\gamma ,\mathrm{iso}}$) of the 22 pulses of 9 Gamma Ray Bursts (GRB) detected by the Fermi satellite. The correlation holds for the individual pulses of each GRB, which shows the reality of the correlation. The derived correlation (Spearman correlation coefficient, $r$, is 0.96) is much stronger compared to the correlations using ${\mathrm{E}}_{\mathrm{peak}}$ (in place of ${\mathrm{E}}_{\mathrm{peak},0}$) determined from the time-integrated spectrum ($r$ = 0.8), or the time-resolved spectrum not accounting for broad pulse structures ($r$ = 0.37), or the pulse-wise spectrum ($r$ = 0.89). Though the improvement in the ${\mathrm{E}}_{\mathrm{peak}}$ - ${\mathrm{E}}_{\gamma ,\mathrm{iso}}$ relation (the Amati relation) for a pulse-wise analysis is known earlier, this is the first time a parameter derived from a joint spectral and timing fit to the data is shown to improve the correlation. We suggest that ${\mathrm{E}}_{\mathrm{peak},0}$, rather than ${\mathrm{E}}_{\mathrm{peak}}$, is intrinsic to a GRB pulse and a natural choice as the parameter in the pulse-wise correlation studies.

6 pages, 2 tables, 2 figures, accepted for publication in ApJ

References in corpus (9)

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Cited by in corpus (9)

• The Epeak-Eiso relation revisited with Fermi GRBs: Resolving a long-standing debate?
• Pulse-wise Amati correlation in Fermi GRBs
• Time-resolved Spectral Study Of Fermi GRBs Having Single Pulses
• Which $E_{\mathrm{peak}}$? - The Characteristic Energy of Gamma-Ray Burst Spectra
• A new method of pulse-wise spectral analysis of Gamma-ray Bursts
• A lingering non-thermal component in the GRB prompt emission: predicting GeV emission from the MeV spectrum
• Time resolved spectral analysis of the prompt emission of long gamma ray bursts with GeV Emission
• GRB as luminosity indicator
• Pulse spectral evolution of GRBs: implication as standard candle