INTEGRAL contributes in the identification of a giant magnetar flare from the Sculptor galaxy NGC 253
On 15 April 2020 a short and strong gamma-ray burst (GRB) was detected
by several Gamma-ray satellites, featuring a fast rise time followed by
an order of magnitude weaker tail. Shortly before 8:42 UT, GRB200415A
triggered the Russian High-Energy Neutron Detector aboard NASA’s Mars
Odyssey satellite; about 400 sec later the burst triggered the Russian
Konus instrument aboard NASA’s Wind satellite. Finally, 4.5 sec later,
the signal reached the Earth environment and triggered INTEGRAL's SPI
and IBIS instruments, NASA’s Fermi instruments and the Atmosphere-Space
Interactions Monitor (ASIM) aboard the International Space Station
(ISS). The light curve shown in the image is the burst as detected by
the bottom layer of INTEGRAL/ISGRI, i.e., the PiCsIT instrument.
Taking advantage of the multiple detections from several spacecrafts
orbiting in different parts of the Solar system, it was possible to
locate the origin of the GRB emission within a narrow error box region:
the radiation came from an extremely magnetized neutron star located in
the neigh-boring galaxy NGC 253, know as the Sculptor galaxy. The
background image shows an optical image of NGC 253, with a red dot
indicating the origin of the burst.
This finding confirms that extremely powerful gamma-ray bursts are
possibly generated by magnetars (neutron stars with extremely high
magnetic fields of the order of 1014 to 1015 Gauss) in relatively
close galaxies. During an active phase magnetars can emit random -
milliseconds to several seconds long - hard-X-ray bursts, with peak
luminosities of 1036 to 1043 erg per second, while
giant flares, which are rare, emit at energies of about 1044
to 1046 erg. Such giant flares from other galaxies are
detectable from instruments aboard satellites orbiting Earth or
travelling in the Solar system.
A portion of the second-long initial pulse of a giant flare, similar to
the one detected from the Sculptor galaxy, in some respect mimics short
GRBs, which have recently been identified as the result from the merger
of two neutron stars accompanied by gravitational-wave emission, i.e.,
GRB170817A and GW170817.
Credits:
A bright gamma-ray flare interpreted as a giant magnetar flare in NGC 253,
D. Svinkin, D. Frederiks, K. Hurley, R. Aptekar, S. Golenetskii,
A. Lysenko, A.V. Ridnaia, A. Tsvetkova, M. Ulanov, T.L. Cline, I.
Mitrofanov, D. Golovin, A. Kozyrev, M. Litvak, A. Sanin, A. Goldstein,
M.S. Briggs, C. Wilson-Hodge, A. von Kienlin, X.-L. Zhang, A. Rau, V.
Savchenko, E. Bozzo, C. Ferrigno, P. Ubertini, A. Bazzano, J.C. Rodi, S.
Barthelmy, J. Cummings, H. Krimm, D.M. Palmer, W. Boynton, C.W. Fellows,
K.P. Harshman, H. Enos & R. Starr,
2021, Nature 589, pages 211–213,
https://doi.org/10.1038/s41586-020-03076-9
