Transient gamma-ray emission from Cygnus X-3 detected by AGILE during the current quenched/hypersoft state
ATel #14662; G. Piano (INAF/IAPS), C. Pittori, F. Verrecchia (SSDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli, V. Fioretti, N. Parmiggiani, A. Addis, L. Baroncelli, A. Di Piano (INAF/OAS-Bo), F. Lucarelli (SSDC and INAF/OAR), S. Vercellone (INAF/OA-Brera), M. Cardillo, A. Ursi, C. Casentini (INAF/IAPS), I. Donnarumma (ASI), F. Gianotti, M. Trifoglio (INAF/OAS-Bo), A. Giuliani, S. Mereghetti, P. Caraveo, F. Perotti (INAF/IASF-Mi), A. Chen (Wits University), A. Argan, E. Costa, E. Del Monte, Y. Evangelista, M. Feroci, F. Lazzarotto, I. Lapshov, E. Menegoni, L. Pacciani, P. Soffitta, V. Vittorini (INAF/IAPS), G. Di Cocco, F. Fuschino, M. Galli, C. Labanti (INAF/OAS-Bo), M. Marisaldi (University of Bergen), A. Pellizzoni, M. Pilia, A. Trois (INAF/OA-Cagliari), G. Barbiellini (INFN Trieste), F. Longo (Univ. Trieste and INFN Trieste), E. Vallazza (INFN Milano Bicocca), A. Morselli, P. Picozza (INFN and Univ. Roma Tor Vergata), M. Prest (Univ. dell'Insubria), P. Lipari, D. Zanello (INFN and Univ. Roma Sapienza), P. W. Cattaneo, A. Rappoldi (INFN Pavia), A. Ferrari (Univ. Torino and CIFS), F. Paoletti (East Windsor RSD Hightstown and INAF/IAPS), L. A. Antonelli (INAF/OAR), P. Giommi, L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 26 May 2021; 16:41 UT
Credential Certification: Giovanni Piano (giovanni.piano@inaf.it)
Subjects: Gamma Ray, >GeV, Binary, Black Hole, Transient
The microquasar Cyg X-3 is currently in a deep quenched state, with a very low hard X-ray emission (Swift/BAT, 15-50 keV; http://swift.gsfc.nasa.gov/results/transients/CygX-3/ ).
AGILE found evidence of transient gamma-ray emission above 100 MeV from Cygnus X-3. Integrating from 2021-05-24 UT 21:00:00 to 2021-05-26 UT 06:00:00 (MJD: ), a preliminary multi-source likelihood analysis yields a detection with a significance of 3.5 sigma and a gamma-ray flux F(>100 MeV) = (5 +/- 2) x 10^-6 photons/cm^2/s.
As detected several times in the past, as Cyg X-3 emerges from such a quenched state, it might show gamma-ray activity, possibly preceding major radio flares with plasmoid ejections (Tavani et al., Nature, 462, 620, 2009). Multifrequency observations of Cyg X-3 during this interesting phase are strongly encouraged.
The AGILE-GRID detection was obtained while AGILE is observing in spinning mode, surveying a large fraction of the sky each day. The source can be monitored with the public mobile application "AGILEScience" developed by the AGILE Team, available for both Android and iOS devices.
