Gamma-ray flare from Cygnus X-3 detected by AGILE
ATel #13458; G. Piano (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli (INAF/IASF-Bo), S. Vercellone (INAF/OA-Brera), P. Caraveo (INAF/IASF-Mi), C. Pittori, F. Lucarelli (SSDC and INAF/OAR), M. Cardillo, A. Ursi, C. Casentini (INAF/IAPS), V. Fioretti, N. Parmiggiani (INAF/IASF-Bo), I. Donnarumma (ASI), F. Gianotti, M. Trifoglio (INAF/IASF-Bo), A. Giuliani, S. Mereghetti, F. Perotti (INAF/IASF-Mi), A. Chen (Wits University), A. Argan, E. Costa, E. Del Monte, Y. Evangelista, M. Feroci, F. Lazzarotto, I. Lapshov, L. Pacciani, P. Soffitta, V. Vittorini (INAF/IAPS), G. Di Cocco, F. Fuschino, M. Galli, C. Labanti (INAF/IASF-Bo), M. Marisaldi (University of Bergen), A. Pellizzoni, M. Pilia, A. Trois (INAF/OA-Cagliari), G. Barbiellini, E. Vallazza (INFN Trieste), F. Longo (Univ. Trieste and INFN Trieste), 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, P. Giommi, L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 7 Feb 2020; 12:18 UT
Credential Certification: Giovanni Piano (giovanni.piano@inaf.it)
Subjects: Gamma Ray, >GeV, Binary, Black Hole, Transient
The microquasar Cyg X-3 entered a quenched/hypersoft state at the beginning of January 2020 (Swift/BAT, 15-50 keV; http://swift.gsfc.nasa.gov/results/transients/CygX-3/ ). AGILE data showed evidence for transient gamma-ray emission during the X-ray spectral transition towards this state (ATel #13423).
After a period of low emission in gamma rays corresponding to the quenched/hypersoft state, AGILE is now detecting enhanced emission.
Integrating from 2020-02-05 UT 00:00:00 to 2020-02-07 UT 00:00:00 (MJD: 58884.0 - 58886.0), a preliminary multi-source likelihood analysis yields a detection with a gamma-ray flux F(>100 MeV) = (3 +/- 1) x 10^-6 photons/cm^2/s, which is at the same level as the one measured during the hard-to-soft X-ray spectral transition for a 2-day integration time (from 2020-01-08 UT 00:00:00 to 2020-01-10 UT 00:00:00, MJD: 58856.0 - 58858.0, ATel #13423).
This gamma-ray flare might precede a major plasmoid ejection, possibly followed by a strong radio outburst.
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.
