Enhanced gamma-ray activity from Cygnus X-3
ATel #12894; G. Piano (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli (INAF/IASF-Bo), M. Cardillo, A. Ursi, C. Casentini (INAF/IAPS), C. Pittori, F. Lucarelli (SSDC and INAF/OAR), V. Fioretti, N. Parmiggiani (INAF/IASF-Bo), I. Donnarumma (ASI), S. Vercellone (INAF/OA-Brera), F. Gianotti, M. Trifoglio (INAF/IASF-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, L. Pacciani, P. Soffitta, V. Vittorini (INAF/IAPS), G. Di Cocco, F. Fuschino, M. Galli, C. Labanti (INAF/IASF-Bo), 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), A. Antonelli, P. Giommi, L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 27 Jun 2019; 12:19 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Giovanni Piano (giovanni.piano@inaf.it)
Subjects: Gamma Ray, >GeV, Binary, Black Hole, Transient
AGILE is detecting gamma-ray emission above 100 MeV from a source positionally consistent with the microquasar Cygnus X-3. Integrating from 2019-06-23 UT 06:00:00 to 2019-06-27 UT 06:00:00 (MJD: 58657.25 - 58661.25), a preliminary multi-source likelihood analysis yields a detection with a significance of ~4.0 sigma and a gamma-ray flux F(>100 MeV) = (2.2 +/- 0.7) x 10^-6 photons/cm^2/s. A much longer integration, from 2019-06-20 UT 06:00:00 to 2019-06-27 UT 06:00:00 (MJD: 58654.25 - 58661.25), yields a detection with a significance of ~4.7 sigma and a gamma-ray flux F(>100 MeV) = (1.9 +/- 0.5) x 10^-6 photons/cm^2/s, demonstrating that Cyg X-3 is undergoing a prolonged gamma-ray activity.
Cyg X-3 entered in quenched/hypersoft state on May 17 (MJD 58620) (Swift/BAT, 15-50 keV; http://swift.gsfc.nasa.gov/results/transients/CygX-3/ ) that usually precedes strong radio/gamma-ray flares. A radio flare was reported on June 19 (MJD 58653; ATel #12880), when Cyg X-3 was emerging from that state.
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.
Multifrequency observations of Cyg X-3 are strongly encouraged.
