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New bright radio flare of GRS 1915+105

ATel #13304; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev, N. N. Bursov, A. V. Shevchenko (SAO RAS, Russia)
on 21 Nov 2019; 20:16 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)

Subjects: Radio, Millimeter, X-ray, Gamma Ray, Binary, Black Hole

Referred to by ATel #: 13308

Today 21 November 2019 (MJD 58808.52) in ongoing monitoring of microquasars with the RATAN-600 radio telescope we have detected very bright flare from GRS1915+105: 290, 440, 390 and 375 mJy at 2.3, 4.7, 8.2 and 11.2 GHz respectively. Such fluxes were in almost three times higher than the fluxes yesterday. Generally such bright events occurred relatively rarely in present time. Last one was detected on 4 June 2019 (see our ATel #12855, where light curves were updated) after two years of silence. The current X-ray data from Swift/BAT (15-50 keV) and MAXI (2-20 keV) show some local activity. The three daily spectra during 19-21 November have dramatically differ: from the inverted one, where the spectral index (SpI) is equal to +0.9 at the lower frequencies, to almost flat spectrum (SpI=+0.04), and to the optically thin synchrotron emission (SpI=-0.2) at the higher frequencies: http://www.sao.ru/hq/lran/XB/1915_sp_2019n.png . Probably such behavior relates with forming of the relativistic jets (Mirabel & Rodriguez, Nature, 1994). The light curves of GRS 1915+105 during from 21 October to 21 November 2019 are shown below. We are conducting the multi-frequency observations daily. Observations in other spectral bands are strongly encouraged.

The RATAN multi-frequency light curves of GRS1915+105 in October-November 2019