The dark burst 010214 with BeppoSAX: variable absorption and jet X-ray emission

Abstract

We report on the prompt and afterglow emission observations of the dark burst GRB010214 with BeppoSAX. The prompt emission shows possible evidence of variable absorption from $N_{\rm H} = 3.0^{+5.1}_{-2.0} \times 10^{23}$ cm-2 in the first 6 s of the event to a value consistent with the Galactic column density ($N_{\rm H}^{\rm G} = 2.66\times 10^{20}$ cm-2) in the GRB direction. An X–ray afterglow emission in the 2–10 keV energy band was detected with BeppoSAX, but an analogue search at lower wavelengths (optical, IR and radio) was unsuccessful. The X–ray afterglow spectrum is consistent with a power–law with Galactic absorption. The light curve shows a complex decay, if the tail of the prompt emission is assumed as the onset of the afterglow: if the origin of the afterglow is coincident with the GRB onset, a bump before ~$3\times10^4$ s is inferred, while if the afterglow is assumed to start later, a steepening of the power–law light curve at $t\sim 3\times10^4$ s is deduced. We discuss these results in the light of the current models of afterglows and the possible origin of the GRB darkness. Finally, we tentatively derive an estimate of the burst redshift.