Ongoing radio monitoring of Cyg X-1 with the RATAN-600 radio telescope

ATel #10459; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev (SAO RAS, Russia)
on 3 Jun 2017; 19:31 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)

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In 2016-2017 we continued monitoring of the X-ray binary and microquasar Cygnus X-1 at 4.7 GHz with the RATAN-600 radio telescope during last 240 days(see ATel #3546, #7322, #9089). We have daily measured the fluxes from Cyg X-1 within a range 5-40 mJy. The frequent increases of fluxes to 40 mJy are not similar to a powerful flares detected from such microquasars as GRS1915+105 or Cyg X-3 when fluxes sharply rose up and slowly decayed. We compared the 4.7 GHz light curve of Cyg X-1 with the Swift/BAT 1d-data at 15-50 keV and MAXI 1d-data at 2-20 keV. In the plot below we can see the strong variability in the radio and the X-ray bands. Some weak correlation (coefficient correlation rho=0.30+-0.05) exists between 4.7-GHz and both X-rays fluxes during MJD 57700-57770 and during MJD 57860-57906 for smoothed radio and MAXI fluxes. Recently Negoro et al. (ATel #10322) and Pooley (ATel #10446) detected the unusual behaviour in Cyg X-1, analysing the MAXI soft fluxes and fluxes at 15 GHz respectively. The reason of such behaviour is probably related with coupling of the accretion disk changes and jets formation, that is a specific feature of the total sample of the microquasars.

The RATAN light curve at 4.7 GHz and daily light curves at 15-50 keV (Swift/BAT) and at 2-20 kev (MAXI) of Cyg X-1 in 2016-2017