GCN Circular 31433
Subject
Konus-Wind detection of GRB 220101A
Event
Date
2022-01-11T18:45:24Z (5 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, D. Frederiks, A. Lysenko, A. Ridnaia,
D. Svinkin, M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, bright GRB 220101A (Swift-BAT trigger #1091101:
Tohuvavohu�� et al., GCN 31347; Markwardt et al., GCN 31369;
Fermi-LAT detection: Arimoto et al., GCN 31350;
AGILE detection: Ursi et al., GCN 31354;
Fermi-GBM detection: Lesage & Meegan, GCN 31360)
triggered Konus-Wind at T0=18695.828 s UT (05:11:35.828).
The burst light curve shows a bright, multi-peaked pulse
which starts at ~T0-147 s and has a total duration of~237 s.
The emission is seen up to ~15 MeV.
The total energy fluence of the burst is 9.05(-0.55,+0.60) erg/cm^2
and the 64-ms peak energy flux, measured from T0 + 18.624 s,
is 4.0(-0.7, +0.7)x10^-6 erg/cm^2/s
(both in the 10 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+90.112 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.58 (-0.13,+0.15),
the high energy photon index beta = -2.62 (-0.53,+0.25),
the peak energy Ep = 257 (-27,+28) keV,
chi2 = 126/119 dof.
The spectrum near the peak count rate (measured from T0+16.640
to T0+24.576 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.51 (-0.16,+0.18),
the high energy photon index beta = -2.55 (-0.64,+0.31),
the peak energy Ep = 314 (-39,+43) keV,
chi2 = 105/96 dof.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220101_T18695/
Assuming the redshift z = 4.618 (Fynbo et al., GCN 31359)
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 following burst rest-frame parameters:
the isotropic energy release Eiso = 3.64(-0.22,+0.25)x10^54 erg,
which is in agreement with Atteia, GCN 31365;
the isotropic luminosity Liso = 9.05(-1.58,+1.58)x10^53 erg/s;
the rest-frame peak energy of the time-integrated spectrum Epi,z =
1416(-157,+152) keV;
and the rest-frame peak energy of the 'peak' spectrum Epp,z =
1764(-219,+242) keV.
With these values, GRB 220101A is within 68% prediction bands for
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW
GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB220101_T18695/GRB220101A_rest_frame.pdf.
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.