Increase of the radio fluxes of Cygnus X-3 after
ATel #11805; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev, A. Erkenov (SAO RAS, Russia)
on 2 Jul 2018; 16:23 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)
Subjects: Radio, Millimeter, Sub-Millimeter, Infra-Red, Optical, X-ray, Gamma Ray, VHE, Binary, Black Hole, Transient
Referred to by ATel #: 11814
We continue the daily monitoring of the microquasars with the RATAN-600 radio telescope and we confirm the increase of activity of microquasar Cygnus X-3, detected with AGILE by Piano at al. (ATel #11804) at >100 MeV. From 1 to 2 July (MJD 58299.966 to 58300.964) the fluxes increased in 4-8 times
at 4.7, 8.2 and 11.2 GHz. Thus it occurred just after (~1 day) the gamma-ray event detected by AGILE.
The spectrum on 2 July is well fitted by the power law:
S[mJy] = 130frequency^(+0.66)[GHz] from 2.3 to 30 GHz. Such high fluxes from Cygnus X-3 at the higher frequencies have been detected in the fist time from April 2017. This flaring event is associated with the almost total "nulling" of the Swift/BAT 15-50 keV flux. According to recent giant flares (ATel #9416, #9444, #9501, #10126) of Cygnus X-3 in 2016 and 2017 we can propose that the microquasar entered in a ultra-soft X-ray state (Koljonen et al., 2010) with coming quench of radio emission, and after which a giant flare (>5 Jy) can most probably occur. Thus the current flaring event could be a precursor of a next bright flare, similar to two flares detected in September 2016 and April 2017 (Trushkin et al., 2017, Koljonen et al., 2018).
RATAN light curves at 4.7 GHz and at 15-50 keV (Swift/BAT) from Cygnus X-3 in June-July 2018
