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Enhanced Gamma-Ray Emission from the Microquasar Cygnus X-3 Detected by AGILE

ATel #10179; G. Piano (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Verrecchia (ASDC and INAF/OAR), S. Vercellone (INAF/OAB),P. Munar-Adrover (INAF/IAPS), A. Bulgarelli (INAF/IASF-Bo), I. Donnarumma (ASI), G. Minervini (INAF/IAPS), V. Fioretti (INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR), E. Striani (CIFS and INAF/IAPS), A. Ursi, M. Cardillo (INAF/IAPS), 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, S. Sabatini, V. Vittorini (INAF/IAPS), G. Pucella, M. Rapisarda (ENEA-Frascati), G. Di Cocco, F. Fuschino, M. Galli, C. Labanti, M. Marisaldi (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), S. Colafrancesco (INAF/OAR and Wits University), N. Parmiggiani (University of Modena and Reggio Emilia), A. Ferrari (Univ. Torino and CIFS), A. Antonelli (ASDC and INAF/OAR), P. Giommi (ASDC), L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 17 Mar 2017; 17:32 UT
Credential Certification: Giovanni Piano (giovanni.piano@iaps.inaf.it)

Subjects: Gamma Ray, >GeV, Request for Observations, Binary, Black Hole

The AGILE-GRID detector is revealing gamma ray emission above 100 MeV from the microquasar Cygnus X-3. Integrating from 2017-03-15 UT 00:00:00 to 2017-03-16 UT 00:00:00, a preliminary multi-source likelihood analysis finds a gamma-ray flux F(>100 MeV) = (4.2 +/- 1.7) x 10^-6 photons/cm^2/s with a detection significance near 4 sigma. The current flux shows an increase with respect to the gamma-ray emission of a few days ago.

Cyg X-3 was recently detected (MJD 57799) in high-energy gamma-rays by AGILE (ATel #10138) and Fermi-LAT (ATel #10109). Hard X-ray emission from this microquasar is currently at a very-low/undetectable level (Swift/BAT, 15-50 keV; http://swift.gsfc.nasa.gov/results/transients/CygX-3/ ). As previously reported, this X-ray spectral state with enhanced gamma-ray emission may precede plasmoid ejection (Tavani et al., Nature, 462, 620, (2009); Abdo et al., Science, 326, 1512 (2009); Piano et al., A&A, 545, A110 (2012)).

We strongly encourage multi-frequency observations of Cygnus X-3.