[vsnet-grb-info 4218] GRB 070110: Ep,i - Eiso correlation
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Tue Jan 16 03:57:41 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6017
SUBJECT: GRB 070110: Ep,i - Eiso correlation
DATE: 07/01/15 18:57:31 GMT
FROM: Lorenzo Amati at INAF-IASF/Bologna <amati at iasfbo.inaf.it>
L. Amati (INAF/IASF Bologna), F. Frontera (Univ. Ferrara and INAF/IASF
Bologna), C. Guidorzi (Univ. Milano Bicocca and INAF/OAB), E. Montanari
(Univ. Ferrara and ITA "Calvi") report:
"Based on the correlation between power-law photon index and peak energy
of GRB spectra measured by Swift/BAT in 15-150 keV (Zhang et al. 2006,
astro-ph/0612238, and Sakamoto et al., ApJ, submitted), the photon index
of 1.57+/-0.12 measured by BAT for GRB 070110 (Cummings et al, GCN 6007)
corresponds to a peak energy Ep of ~110+/-50 keV. From this spectral
information and the reported 15-150 keV fluence of (1.6+/-0.1)x10^-6
erg/cm2 (GCN 6007), by assuming a Band spectral shape and by taking into
account the redshift of 2.352 (Jaunsen et al., GCN 6010), it is then
possible to estimate the values of the intrinsic peak energy, Ep,i ~
370+/-170 keV, and of the isotropic equivalent radiated energy in the
1-10000 keV cosmological rest frame, Eiso ~ (5.5+/1.5)x10^52 erg (the
uncertainties on Ep,i and Eiso take approximately into account the
measurements errors, the scatter of the photon index - peak energy
correlation and the dependence of Eiso on the values assumed for alpha and
beta in the Band spectral model).
These values are consistent within 2 sigma with the Ep,i-Eiso correlation.
If, conservatively, we assume a Band model with alpha equal to the power-law
spectral index measured by BAT and beta = -2.3, we find that GRB 070110 is
consistent with the Ep,i-Eiso correlation within 2 sigma for a measured Ep up
to ~170 keV (E0 ~400 keV), and within 3 sigma for a measured Ep up to ~280 keV
(E0 ~650 keV). These values of E0 are well above the upper bound of the BAT
energy band used for spectral analysis (150 keV).
Thus, we conclude that, despite the very peculiar behaviour shown by its
X-ray afterglow after ~20 ks from the burst onset (Krimm et al.,
GCN_Report 26.2), GRB 070110 seems to be a common long event from the
point of its position in the Ep,i-Eiso plane. This, together with the
standard behaviour of the early afterglow light curve (steep decay, flat
decay) could indicate that the emission mechanisms / environment
originating the prompt emission are not necessarily linked to those
producing the LATE afterglow emission."
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