Abstract
We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-ray Monitor (WXM) and French Gamma Telescope observations of XRF 030723 along with observations of the XRF afterglow made using the 6.5 m Magellan Clay telescope and Chandra. The observed peak energy Epkobs of the vFv 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 Epkobs = 8.4-3.4 +3.5 keV. The ratio of X-ray to γ-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 Eiso and E pk'satisfy the relation discovered by Amati et al. (2002), a redshift of z = 0.38-0.18+0.36 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 that is due to a progenitor wind.
Original language | English (US) |
---|---|
Pages (from-to) | 884-893 |
Number of pages | 10 |
Journal | Astrophysical Journal |
Volume | 621 |
Issue number | 2 I |
DOIs | |
State | Published - Mar 10 2005 |
Externally published | Yes |
Keywords
- Gamma rays: bursts
- Supernovae: general
- X-rays: general
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science