GCN Circular 38104
Subject
GRB241105A: Fermi GBM Observation of a Short Burst with Extended Emission
Date
2024-11-06T19:06:27Z (2 months ago)
From
sumanbala2210@gmail.com
Via
Web form
U. Pathak (IITB), O. Mukherjee (USRA), S. Rushikesh (IISER, TVM), S. Bala (USRA),
O.J. Roberts (USRA/NASA-MSFC), E. Burns (LSU), P. Veres (UAH) and C. Meegan (UAH)
report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 16:06:04.66 UT on 05 November 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB241105A (trigger 752515569/241105671),
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2024, GCN 38091),
GOTO (Julakanti et al. 2024, GCN 38088), Swift-XRT (Kennea et al. 2024, GCN 38098),
and SVOM/VT (Qiu et al. 2024, GCN 38099). The spectroscopic redshift of the optical
counterpart observered by VLT/FORS2 (Izzo et al. 2024, GCN 38097) is 2.702.
The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.
The angle from the Fermi LAT boresight is 145 degrees.
The GBM light curve consists of a short single pulse with a duration (T90)
of about 1.4 s (50-300 keV) followed by significant extended emission for ~91 (50-300 keV)
seconds. The extended emission appears to contain more fluence than the initial spike.
The time-averaged spectrum from T0-0.5 to T0+2.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.1 and the cutoff energy,
parameterized as Epeak, is 702 +/- 278 keV. Considering the redshift of 2.702,
and best fit model, we find the isotropic equivalent luminosity Liso = 7.5e+52 erg s-1 (1-10000 keV).
The event fluence (10-1000 keV) in this time interval is
(2.8 +/- 0.2)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.19 s in the 10-1000 keV band is 11 +/- 3 ph/s/cm^2.
The total emission (short pulse + extended emission) from T0-2.6 to T0+97 s is best fit by
a power law function with photon index -1.42 +/- 0.04. The total fluence (10-1000 keV)
in this time interval is (1.1 +/- 0.1)E-05 erg/cm^2.
Using z=2.702, we find Eiso = 1.5e+53 erg (1-10000 keV) when fitting the spectrum
with a power law function with an exponential high-energy cutoff, with a power-law index of
-0.03 +/- 0.4 and cutoff energy, parameterized as Epeak, of 221 +/- 30 keV.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"