Hardness ratio evolutionary curves of gamma-ray bursts expected by the curvature effect
arXiv:astro-ph/0701078 · doi:10.1103/PhysRevD.74.063005
Abstract
We have investigated the gamma-ray bursts pulses assumed to arise from relativistically expending fireballs. We find, due to the curvature effect, the evolutionary curve of the raw hardness ratio (when the background count is included) varies significantly, depending on the hardness of a burst. For a soft burst, an upside-down pulse of its raw hardness ratio curve (HRC) would be observed; for a hard burst, its raw HRC shows a pulse-like profile with a sinkage in its decaying phase; for a very hard burst, the raw HRC possesses a pulse-like profile without a sinkage in its decaying phase. For a pulse-like raw HRC as shown in the case of the hard and very hard bursts, its peak would appear in advance of that of the corresponding light curve. We have studied here the HRC of GRB 920216, GRB 920830 and GRB 990816 in detail. The features of the raw HRC expected in the hard burst are observed in these bursts. A fit to the three bursts shows that the curvature effect alone could indeed account for the predicted characteristics of HRCs. In addition, we find that the observed hardness ratio tends to be harder at the beginning of the pulses than what the curvature effect could predict and be softer at the late time of the pulses. We believe this is an evidence showing the existence of intrinsic hard-to-soft radiation.
26 pages, 8 figures, 1 table
References in corpus (24)
- The BATSE Gamma-Ray Burst Spectral Catalog. I. High Time Resolution Spectroscopy of Bright Bursts using High Energy Resolution Data
- Connection Between Energy-dependent Lags And Peak Luminosity In Gamma-ray Bursts
- Expanding Relativistic Shells and Gamma-Ray Burst Temporal Structure
- Gamma-Ray Burst Peak Duration as a Function of Energy
- Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst Prompt Emissions and X-ray Flares with Swift Data
- Synchrotron Radiation as the Source of Gamma-Ray Burst Spectra
- Towards a More Standardized Candle Using GRB Energetics and Spectra
- Search for Relativistic Curvature Effects in Gamma-Ray Burst Pulses
- Gamma-Ray Bursts from Up-Scattered Self-Absorbed Synchrotron Emission
- On the Hardness-Intensity Correlation in Gamma-Ray Burst Pulses
- Spectral lags and the energy dependence of pulse width in gamma-ray bursts: contributions from the relativistic curvature effect
- Gamma-Ray Burst Spectra and Light Curves as Signatures of a Relativistically Expanding Plasma
- Characteristics of profiles of gamma-ray burst pulses associated with the Doppler effect of fireballs
- Spectral lags caused by the Doppler effect of fireballs
- On the Variety of the Spectral and Temporal Behaviors of Long Gamma-Ray Burst Pulses
- On the Time Evolution of Gamma-Ray Burst Pulses: A Self-Consistent Description
- Spectral Features from Ultrarelativistic Ions in Gamma-Ray Bursts?
- The Pulse Scale Conjecture and the Case of BATSE Trigger 2193
- Relationship between the gamma-ray burst pulse width and energy due to the Doppler effect of fireballs
- A test of the power law relationship between gamma-ray burst pulse width ratio and energy expected in fireballs or uniform jets
- Deviation of light curves of gamma-ray burst pulses from standard forms due to the curvature effect of spherical fireballs or uniform jets
- Gamma-Ray Burst Spectral Features: Interpretation as X-ray Emission From A Photoionized Plasma
- Emission and absorption lines of gamma-ray bursts affected by the relativistic motion of fireball ejecta
- The FWHM of local pulses and the corresponding power-law index of gamma-ray burst FRED pulses
Cited by in corpus (8)
- Gamma-Ray Bursts in the Swift Era
- A Statistical Study of GRB X-ray Flares: Evidence of Ubiquitous Bulk Acceleration in the Emission Region
- The full curvature effect expected in early X-ray afterglow emission of gamma-ray bursts
- Spectral lag of gamma-ray burst caused by the intrinsic spectral evolution and the curvature effect
- The softening phenomenon due to the curvature effect: in the case of extremely short intrinsic emission
- Spectral hardness evolution characteristics of tracking Gamma-ray Burst pulses
- Two types of softening detected in X-ray afterglows of Swift bursts: internal and external shock origins?
- Development of the spectrum of gamma-ray burst pulses influenced by the intrinsic spectral evolution and the curvature effect