The bright radio flare from microquasar GRS 1915+105
ATel #16976; S. A. Trushkin, P. G. Tsybulev, A. V. Shevchenko, N. N. Bursov, N. A. Nizhelskij (SAO RAS, Russia)
on 13 Jan 2025; 15:17 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)
Subjects: Radio, Millimeter, Infra-Red, X-ray, Binary, Black Hole
Referred to by ATel #: 16991
During current long-term monitoring of microquasars we have detected the bright flare from the microquasar GRS1915+105 with the RATAN-600 radio telescope. Firstly source was detected 3 and 6 January 2025 at level 20 mJy at 4.7 GHz after long period of nondetection lower 5 mJy. Today on 13 January 2025 (MJD 60688.373)
we have measured the fluxes: 1240 +/- 40, 1805 +/- 30, 1890 +/-30, 1745 +/- 30, 1335 +/- 40, 980 +/-40, and 740 +/-40 mJy at 2.3, 4.7, 8.2, 11.2, 14.4, 22.3 and 30.0 GHz respectively. The spectrum of the flare consists of two parts - the optically thick part at frequencies lower 5 GHz with spectral index/equal to +0.52, and the optically thin one at the higher frequencies, where the power law spectrum has spectral index, equal to -0.76. See the daily spectra of the source
here.
11 January we have observed GRS1915+105 with multi-azimuthal antennas of RATAN-600 during 6h - 11h UT
at 4.7, 8.2, and 14.4 GHz and found that spectral index changed from -0.8 to -0.4 showing the beginning of
the new active event at two higher frequencies.
Because the activity continues future multi-band observations can be very useful.
The radio light curves of the GRS1915+105 in 2025