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arXiv · 1405.4114

Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra

S. Campana·M. G. Bernardini·V. Braito·G. Cusumano·P. D'Avanzo·V. D'Elia·G. Ghirlanda·G. Ghisellini·A. Melandri·R. Salvaterra·G. Tagliaferri·S. D. Vergani
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Abstract

We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of Gamma Ray Burst (GRB) afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power law shape with index 2.4. However, for real instruments, this value depends on their low energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 10^5-10^6 counts in the 0.3-10 keV band are needed to constrain the redshift with 10% accuracy. As a test case we discuss the XMM-Newton observation of GRB 090618 at z=0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

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S. Campana, M. G. Bernardini, V. Braito, G. Cusumano, P. D'Avanzo, V. D'Elia, G. Ghirlanda, G. Ghisellini, A. Melandri, R. Salvaterra, G. Tagliaferri, S. D. Vergani. 2014-05-16. Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra. https://doi.org/10.1093/mnras%2Fstu831

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