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New giant radio flare from Cyg X-3, correlated with X-rays and gamma-ray flares

ATel #13835; S. A. Trushkin, N. N. Bursov, A. V. Shevchenko, N. A. Nizhelskij, P. G. Tsybulev, A. N. Borisov (SAO RAS, Russia)
on 26 Jun 2020; 20:19 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)

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

Referred to by ATel #: 13866, 14298, 14821

In the current multi-frequency monitoring of the Galactic microquasars with the RATAN-600 radio telescope we have detected a bright flare (probably a giant one) at 2.3-30 GHz from the well-known strongly flaring microquasar Cyg X-3 (see ATel #13461). On 26 June 2020 (MJD 59025.979) we have detected fluxes 1.1, 3.72, 5.67, 5.97, 4.97 and 3.35 Jy at 2.3, 4.7, 8.2, 11.2, 22.3 and 30 GHz respectively while these fluxes were about 0.1 Jy a day before. Thus Cyg X-3 is in the beginning of jets ejection that is usually characterized by two regimes: an optically thick one at frequencies lower 5 GHz and by an optically thin one at frequencies higher 8 GHz. The Swift/BAT data (http://swift.gsfc.nasa.gov/results/transients/CygX-3.orbit.lc.txt) show the very strong increase of hard X-ray flux at 15-50 keV around MJD59025.984. Moreover in the Fermi Gamma-ray data (https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/CygnusX-3_86400.lc) anyone can find two recent significant flux points at 0.1-300 GeV (MJD 59019.5 and 59025.5) just associated with two last radio flares detected with RATAN-600 (see the plot below). Thus we can undoubtedly say about a case of a clear association of flaring events in the radio, X-ray and Gamma-ray bands. It could be related with so-called the disk-jet coupling in the X-ray binary stars (Fender at al. 2004) as a result of a jet production in the process of variable massive accretion onto a black hole. We continue the daily multi-frequency observations in the '31-azimuths mode' of RATAN-600 during +/-2.5 hours around the local culmination (~23:30 UT) of Cyg X-3. Any radio and X-ray observations of Cyg X-3 could be very useful.

The light curves of Cygnus X-3 in April-June 2020 in Gamma-rays, in hard X-rays and in radio band.