|HETE Burst H3862|
Burst H3862 summary
Download ASCII table of Fregate Band A, B, C lightcurves here.
An automated fit of a cutoff power-law spectrum has been performed for H3862. The fit of the model to the data is shown below; the calculated values of Epeak and the burst fluence (25-100 keV) are:
Epeak = 93.50 keV Fluence = 6.706e-07 erg/cm^2 Duration = 0.500 seconds PseudoZ = 2.096
These results are computed by an automatic script. Please visually inspect the XSPEC summary plot to judge the quality of the results.
Please note that this value of Epeak results from a fit to FREGATE data (8-400 keV) only -- a more reliable joint fit to FREGATE and WXM data is not yet automated. As such, this Epeak estimate is likely to be biased high, especially for soft events, such as XRFs. In our experience, the inclusion of WXM data can lower the value of E_peak substantially. The above Epeak value should thus be viewed as a preliminary estimate. As better fits become available, the information will be posted here.
Click here for an explanation of the method.
Skymap for HETE trigger H3862
GRB 050709: Refined Spectral and Temporal Properties M. Boer, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley, on behalf of the HETE Science Team; M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, J. Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, K. Tanaka, Y. Yamamoto, and A. Yoshida, on behalf of the HETE WXM Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE FREGATE Team; report: We have performed a joint fit to the WXM and FREGATE spectral data for GRB 050709, in order to refine the numbers initially reported in GCN 3570 (Butler et al. 2005) for the short and long pulse components. The short pulse is well-fit (chi2/DOF= 35.37/48) by a power-law times exponential model with photon index alpha = -0.7 +/- 0.2 and nu-F_nu peak energy Epeak = 83 +18/-12 keV. The energy fluences of the short pulse are S_E(2-30 keV) = (9.3 +/- 0.9) x 10^(-8) erg cm^-2 and S_E(30-400 keV) = (2.9 +/- 0.4) x 10^(-7) erg cm^-2. The X-ray to gamma-ray fluence ratio is thus 0.32. The t90 duration of the short pulse is 220 +/- 50 ms in the 2-25 keV energy band and 70 +/- 10 ms in the 30-400 keV band. The t90 duration and Epeak of the short pulse are consistent with those found for short/hard GRBs (see, e.g., Ghirlanda, Ghisellini, & Celotti 2004, A&A, 422, L55 for plots of the short/hard GRB Epeak distribution). The long pulse is well fit (chi2/DOF = 108.86/138) by a power-law model with photon index beta = -2.2 +0.2/-0.4. The energy fluences of the long pulse are S_E(2-30 keV) = (7.1 +/- 1.5) x 10^(-7) erg cm^-2 and S_E(30-400 keV) = (3.9 +4.1/-2.7) x 10^(-7) erg cm^-2. These spectral results are preliminary because there is a linear trend in the background that affects the spectral analysis of the long pulse and has not yet been taken into account. The t90 of the long pulse is 130 +/- 7 s in the 2-25 keV energy band. Using the redshift of z = 0.16 measured by Price et al. (2005; GCN 3605), the isotropic-equivalent energy of the short pulse in the 1-10,000 keV energy band in the rest frame of the source is Eiso (short pulse) = (2.7 +1.1/-0.3) x 10^(49) erg, using Omega_M=0.3, Omega_Lambda=0.7, and h=0.65. The Eiso and Epeak values for the short pulse place it well off of the Amati et al. (2002; A&A, 390, 81) relation for long duration GRBs. Taking a time interval 0.060 s in the rest frame of the source (corresponding to t90 = 0.07 s in the 30-400 keV energy band in the observer frame) and assuming the same cosmology and energy band as used above for the Eiso determination, the luminosity of the short pulse in the 1-10,000 keV energy band in the rest frame of the source is Liso (short pulse) = (5.2 +/- 1.4) x 10^(50) erg s^-1. Taking even this short time interval, the Liso and Epeak values for the short pulse place it off the Yonetoku et al. (2004; ApJ, 609, 935) correlation for long duration GRBs.
Link to Jochen Greiner's web page on GRB050709