In:
Publications of the Astronomical Society of Japan, Oxford University Press (OUP), Vol. 59, No. sp1 ( 2007-01-30), p. S361-S367
Abstract:
Results are presented of early X-ray afterglow observations of GRB 060105 by Swift and Suzaku. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope at 06:49:28 on 2006 January 5 ($T_0$). The Suzaku team commenced a pre-planned target of opportunity observation at 19 ks (5.3 hr) after the Swift trigger. The X-ray flux faded during observations from $6.8 \times 10^{-9} \,\mathrm{erg} \,\mathrm{s}^{-1} \,\mathrm{cm}^{-2}$ (at $T_0 + 87 \,\mathrm{s}$ with the Swift/XRT) to $1.5 \times 10^{-13} \,\mathrm{erg} \,\mathrm{s}^{-1} \,\mathrm{cm}^{-2}$ [at $T_0 + 94 \hbox{}{--} 101 \,\mathrm{ks}$ with the Suzaku X-ray Imaging Spectrometer (XIS)] in the 2–10 keV energy band. Following prompt emission and successive very steep decay, a shallow decay was observed from $T_0 + 187 \,\mathrm{s}$ to $T_0 + 1287 \,\mathrm{s}$. After an observation gap during $T_0 + (1.5 \hbox{}{--} 3) \;\mathrm{ks}$, an extremely early steep decay was observed in $T_0 + (4 \hbox{}{--} 30) \;\mathrm{ks}$. The lightcurve flattened again at $T_0 + 30 \,\mathrm{ks}$, and another steep decay followed from $T_0 + 50 \,\mathrm{ks}$ to the end of observations. Both steep decays exhibited decay indices of 2.3–2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below $1^\circ$. The unique Suzaku/XIS data allow us to set very tight upper limits on line emission or absorption in this GRB. For the reported pseudo-redshift of $z = 4.0 \pm 1.3$ the upper limit on the iron line equivalent width is 50 eV.
Type of Medium:
Online Resource
ISSN:
0004-6264
,
2053-051X
DOI:
10.1093/pasj/59.sp1.S361
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2007
detail.hit.zdb_id:
2206640-8
detail.hit.zdb_id:
2083084-1
SSG:
16,12
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