The statistics of BAT-to-XRT flux ratio in GRB: Evidence for a characteristic value and its implications

Abstract

We present the statistics of the ratio, $\mathcal{R}$, between the prompt and afterglow "plateau" fluxes of GRB. This we define as the ratio between the mean prompt energy flux in {\em Swift} BAT and the {\em Swift} XRT one, immediately following the steep transition between these two states and the beginning of the afterglow stage referred to as the "plateau". Like the distribution of many other GRB observables, the histogram of $\mathcal{R}$~ is log-normal with maximum at a value ${\mathcal{R}}_m\simeq 2,000$, FWHM of about 2 decades and with the entire distribution spanning about 5 decades in the value of $\mathcal{R}$. We note that the peak of the distribution is close to the proton-to-electron mass ratio $({\mathcal{R}}_m\simeq m_p/m_e=1836)$, as proposed to be the case in an earlier publication, on the basis of a specific model of the GRB dissipation process. It therefore appears that, in addition to the values of the energy of peak luminosity $E_{\mathrm{pk}}\sim m_e{c}^2$, GRB present us with one more quantity with an apparent characteristic value. The fact that the values of both these quantities (\Ep~and \R) are consistent with the same specific model invoked to account for the efficient conversion of their relativistic proton energies to electrons, argues favorably for its underlying assumptions.

arXiv comment12 pages, 5 figures, published in the Astrophysical Journal

References in corpus (34)

• Spectra and Light Curves of Gamma-Ray Burst Afterglows
• Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs
• Physical processes shaping GRB X-ray afterglow lightcurves: theoretical implications from the Swift XRT observations
• Jets in GRBs
• Discovery of the X-Ray Afterglow of the Gamma-Ray Burst of February 28 1997
• Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data
• The shock break-out of GRB 060218/SN 2006aj
• Bright X-ray Flares in Gamma-Ray Burst Afterglows
• Connection Between Energy-dependent Lags And Peak Luminosity In Gamma-ray Bursts
• Fermi Observations of GRB 090902B: A Distinct Spectral Component in the Prompt and Delayed Emission
• Fermi Observations of GRB 090510: A Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 keV to GeV Energies
• The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts
• Gamma-Ray Bursts in the Swift Era
• Jet breaks and Energetics of Swift GRB X-ray Afterglows
• An unexpectedly rapid decline in the X-ray afterglow emission of long gamma-ray bursts
• A time - luminosity correlation for Gamma Ray Bursts in the X - rays
• GRB110721A: An extreme peak energy and signatures of the photosphere
• Implications of Lag-Luminosity Relationship for Unified GRB Paradigms
• The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts
• Synchrotron and SSC Emission and the Blast-Wave Model of Gamma-Ray Bursts
• Magnetar powered GRBs: Explaining the extended emission and X-ray plateau of short GRB light curves
• Discovery of a tight correlation for gamma ray burst afterglows with `canonical' light curves
• Determination of the intrinsic Luminosity Time Correlation in the X-ray Afterglows of GRBs
• Fermi and Swift Gamma-Ray Burst Afterglow Population Studies
• The updated luminosity correlations of gamma-ray bursts and cosmological implications
• Signatures of a Maxwellian Component in Shock-Accelerated Electrons in GRBs
• The spectral-temporal properties of the prompt pulses and rapid decay phase of GRBs
• Realistic analytic model for the prompt and high latitude emission in GRBs
• Coasting external shock in wind medium: an origin for the X-ray plateau decay component in Swift GRB afterglows
• Luminosity correlations for gamma-ray bursts and implications for their prompt and afterglow emission mechanisms
• The Optical Variability of the Quasar 3C~279: The Signature of a Decelerating Jet?
• The supercritical pile gamma-ray burst model: The GRB afterglow steep-decline-and-plateau phase
• The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution
• Effects of a low electron distribution cutoff on multiwavelength spectra and light curves of GRB afterglows

Cited by in corpus (2)

• A MAD Model for Gamma-Ray Burst Variability
• GRB X-Ray Flare Properties among Different GRB Subclasses