TITLE: GCN CIRCULAR NUMBER: 38103 SUBJECT: Konus-Wind detection of GRB 241105A (short with extended emission) DATE: 24/11/06 18:53:19 GMT FROM: Dmitry Frederiks at Ioffe Institute fred@mail.ioffe.ru
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The likely short GRB 241105A (Fermi GBM team, GCN 38085) triggered Konus-Wind (KW) at T0=57966.516 s UT (16:06:06.516).
The burst light curve shows a short initial pulse, which starts at ~T0-0.5 s, peaks at ~T0, and has a total duration of ~1.5 s, which was followed by a weaker extended emission, visible in KW up to ~T0+60 s. The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB241105_T57966/
As observed by Konus-Wind, the burst had a fluence of (2.01 ± 0.47)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 - 0.064 s, of (2.37 ± 0.30)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+57.640 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.69 (-0.37,+0.67), the high energy photon index beta = -1.76 (-0.55,+0.21), the peak energy Ep = 374 (-165,+437) keV, chi2 = 98/97 dof.
The spectrum of the initial pulse alone (measured from T0-0.512 s to T0+0.960 s) can be described by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.90(-0.15,+0.15) and Ep = 417(-82,+111) keV.
Assuming the redshift z=2.702 (Izzo et al., GCN 38097) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the burst isotropic energy release E_iso to (3.42 ± 0.80)x10^53 erg, the isotropic peak luminosity L_iso to (1.49 ± 0.18)x10^53 erg/s, the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~1380 keV, and the rest-frame peak energy at the peak of the emission Ep,p,z to ~1540 keV. With the obtained estimates, GRB 241105A fits 68% prediction bands for both 'Amati' and 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB241105_T57966/GRB241105A_rest_frame.pdf
All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.
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