학술논문
High Energy Observations of XRF 030723: Evidence for an Off-axis Gamma-Ray Burst?
Document Type
Working Paper
Author
Butler, N. R.; Sakamoto, T.; Suzuki, M.; Kawai, N.; Lamb, D. Q.; Graziani, C.; Donaghy, T. Q.; Dullighan, A.; Vanderspek, R.; Crew, G. B.; Ford, P.; Ricker, G.; Atteia, J-L.; Yoshida, A.; Shirasaki, Y.; Tamagawa, T.; Torii, K.; Matsuoka, M.; Fenimore, E. E.; Galassi, M.; Doty, J.; Villasenor, J.; Prigozhin, G.; Jernigan, J. G.; Barraud, C.; Boer, M.; Dezalay, J-P.; Olive, J-F.; Hurley, K.; Levine, A.; Martel, F.; Morgan, E.; Woosley, S. E.; Cline, T.; Braga, J.; Manchanda, R.; Pizzichini, G.
Source
Astrophys.J. 621 (2005) 884-893
Subject
Language
Abstract
We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-ray Monitor/French Gamma Telescope observations of XRF030723 along with observations of the XRF afterglow made using the 6.5m Magellan Clay telescope and the Chandra X-ray Observatory. The observed peak energy E_pk_obs of the nu F_nu burst spectrum is found to lie within (or below) the WXM 2-25 keV passband at 98.5% confidence, and no counts are detected above 30 keV. Our best fit value is E_pk_obs=8.4+3.5/-3.4 keV. The ratio of X-ray to Gamma-ray flux for the burst follows a correlation found for GRBs observed with HETE-2, and the duration of the burst is similar to that typical of long-duration GRBs. If we require that the burst isotropic equivalent energy E_iso and E_pk_rest satisfy the relation discovered by Amati et al. (2002), a redshift of z=0.38+0.36/-0.18 can be determined, in agreement with constraints determined from optical observations. We are able to fit the X-ray afterglow spectrum and to measure its temporal fade. Although the best-fit fade is shallower than the concurrent fade in the optical, the spectral similarity between the two bands indicates that the X-ray fade may actually trace the optical fade. If this is the case, the late time rebrightening observed in the optical cannot be due to a supernova bump. We interpret the prompt and afterglow X-ray emission as arising from a jetted GRB observed off-axis and possibly viewed through a complex circumburst medium due to a progenitor wind.
Comment: 14 pages, 9 figures, to appear in ApJ
Comment: 14 pages, 9 figures, to appear in ApJ