AGILE detection of Cygnus X-3 γ-ray active states during the period mid-2009 / mid-2010

Context. Cygnus X-3 (Cyg X-3) is a well-known microquasar producing v ariable emission at all wavelengths. Cyg X-3 is a prominent X-ray binary producing relativistic jets, and studying its high energy emission is crucial for the understanding of the fundamental acceleration processes in accreting compact objects. Aims. Our goal is to study extreme particle acceleration and γ-ray production above 100 MeV during special spectral state of Cyg X3 usually characterized by a low hard X-ray flux and enhanced s oft X-ray states. Methods. We observed Cyg X-3 with the AGILE satellite in extended time int rvals from 2009 Jun.–Jul, and 2009 Nov.–2010 Jul. We report here the results of the AGILE γ-ray monitoring of Cyg X-3 as well as the results from extensi ve multiwavelength campaigns involving radio (RATAN-600, AMI-LA and Metsähovi Radio Ob servatories) and X-ray monitoring data (XTE and Swift). Results. We detect a series of repeated γ-ray flaring activity from Cyg X-3 that correlate with the sof t X-ray states and episodes of decreasing or non-detectable hard X-ray emission. Further more, we detect γ-ray enhanced emission that tends to be associated with radio flares greater than 1 Jy at 15 GHz, confirming a trend alre ady detected in previous observations. The source remained ctive above 100 MeV for an extended period of time (almost 1.5 month s in 2009 Jun.–Jul and 1 month in 2010 May). We study in detail the short timescale γ-ray flares that occurred before or near the radio peaks. Conclusions. Our results confirm the transient nature of the extreme parti cle acceleration from the microquasar Cyg X-3. A series of repeatedγ-ray flares shows correlations with radio and X-ray emission c firming a well established trend of emission. We compare our results with Fermi-LAT and MAGIC TeV observations of Cyg X-3.