2016ApJ...818..167W -
Astrophys. J., 818, 167 (2016/February-3)
On the late-time spectral softening found in X-ray afterglows of gamma-ray bursts.
WANG Y.-Z., ZHAO Y., SHAO L., LIANG E.-W. and LU Z.-J.
Abstract (from CDS):
Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around the circumburst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening we now systematically search the X-ray afterglows detected by the X-ray telescope aboard Swift and collect 12 GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal and spectral features. For some well-observed bursts with high-quality data, the time-resolved spectra could be well-produced within the scattering scenario by taking into account the X-ray absorption from the circumburst medium. We also find that during spectral softening the power-law index in the high-energy end of the spectra does not vary much. The spectral softening is mainly manifested by the spectral peak energy continually moving to the soft end.
Abstract Copyright:
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Journal keyword(s):
dust, extinction - gamma-ray burst: general - ISM: general - scattering - X-rays: general
Simbad objects:
14
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