2007A&A...470..105M


Query : 2007A&A...470..105M

2007A&A...470..105M - Astronomy and Astrophysics, volume 470, 105-118 (2007/7-4)

Swift observations of GRB 060614: an anomalous burst with a well behaved afterglow.

MANGANO V., HOLLAND S.T., MALESANI D., TROJA E., CHINCARINI G., ZHANG B., LA PAROLA V., BROWN P.J., BURROWS D.N., CAMPANA S., CAPALBI M., CUSUMANO G., DELLA VALLE M., GEHRELS N., GIOMMI P., GRUPE D., GUIDORZI C., MINEO T., MORETTI A., OSBORNE J.P., PANDEY S.B., PERRI M., ROMANO P., ROMING P.W.A. and TAGLIAFERRI G.

Abstract (from CDS):

GRB 060614 is a remarkable gamma-ray burst (GRB) observed by Swift with puzzling properties, which challenge current progenitor models. In particular, the lack of any bright supernova (SN) down to very strict limits and the vanishing spectral lags during the whole burst are typical of short GRBs, strikingly at odds with the long (102 s) duration of this event. Here we present detailed spectral and temporal analysis of the Swift observations of GRB 060614. We show that the burst presents standard optical, ultraviolet and X-ray afterglows, detected beginning 4ks after the trigger. An achromatic break is observed simultaneously in the optical and X-ray bands, at a time consistent with the break in the R-band light curve measured by the VLT. The achromatic behaviour and the consistent post-break decay slopes make GRB060614 one of the best examples of a jet break for a Swift burst. The optical and ultraviolet afterglow light curves have also an earlier break at 29.7±4.4ks, marginally consistent with a corresponding break at 36.6±2.4ks observed in the X-rays. In the optical, there is strong spectral evolution around this break, suggesting the passage of a break frequency through the optical/ultraviolet band. The very blue spectrum at early times suggests this may be the injection frequency, as also supported by the trend in the light curves: rising at low frequencies, and decaying at higher energies. The early X-ray light curve (from 97 to 480s) is well interpreted as the X-ray counterpart of the burst extended emission. Spectral analysis of the BAT and XRT data in the ∼80s overlap time interval show that the peak energy of the burst has decreased to as low as 8keV at the beginning of the XRT observation. Spectral analysis of following XRT data shows that the peak energy of the burst continues to decrease through the XRT energy band and exits it at about 500s after the trigger. The average peak energy Ep of the burst is likely below the BAT energy band (<24keV at the 90% confidence level) but larger than 8keV. The initial group of peaks observed by BAT (∼5s) is however distinctly harder than the rest of the prompt emission, with a peak energy of about 300keV as measured by Konus Wind. Considering the time-averaged spectral properties, GRB 060614 is consistent with the Eiso-Eprest, Eγ-Eprest, and Lp,iso-Eprest correlations.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts - X-rays: individual: GRB 060614

Simbad objects: 18

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Number of rows : 18
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 SN 2006aj SN* 03 21 39.670 +16 52 02.27 17.96 19.11 17.40     SNIc-BL 932 1
2 GRB 060313 gB 04 26 28.180 -10 50 37.95 20.55 21.03 19.66     ~ 145 0
3 GRB 060729 gB 06 21 31.850 -62 22 12.69           ~ 280 0
4 GRB 061006 gB 07 24 07.660 -79 11 55.10           ~ 191 1
5 SN 2003lw SN* 08 02 30.1 -39 51 03       20.23   SNIc: 543 0
6 GRB 051227 gB 08 20 58.107 +31 55 32.01           ~ 121 0
7 GRB 060121 gB 09 09 51.930 +45 39 45.41           ~ 122 1
8 GRB 061210 gB 09 38 05.270 +15 37 17.30           ~ 134 0
9 SN 2003dh SN* 10 44 50.030 +21 31 18.15     16.2     SNIcpec 1202 1
10 GRB 050416 gB 12 33 54.600 +21 03 26.69     19.12     ~ 281 1
11 GRB 050724 gB 16 24 44.400 -27 32 27.90     19.70     ~ 434 1
12 SN 1998bw SN* 19 35 03.17 -52 50 46.1   14.09       SNIc 1814 2
13 GRB 060614 gB 21 23 32.140 -53 01 36.10 18.89 20.12 19.54     ~ 598 1
14 GRB 051221 gB 21 54 48.626 +16 53 27.16 19.49         ~ 349 1
15 GRB 051210 gB 22 00 40.930 -57 36 47.10           ~ 125 0
16 GRB 061201 gB 22 08 32.060 -74 34 47.90           ~ 183 0
17 GRB 050709 gB 23 01 26.960 -38 58 39.50           ~ 293 1
18 GRB 050803 gB 23 22 37.910 +05 47 09.00           ~ 116 0

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