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AGILE Detection of Enhanced Gamma-Ray Emission from the Microquasar Cygnus X-3

ATel #10138; G. Piano (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), P. Munar-Adrover (INAF/IAPS), A. Bulgarelli (INAF/IASF-Bo), F. Verrecchia (ASDC and INAF/OAR), I. Donnarumma (ASI), G. Minervini (INAF/IAPS), V. Fioretti (INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR), S. Vercellone (INAF/IASF-Pa), 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), F. Paoletti (East Windsor RSD Hightstown and INAF/IAPS), A. Antonelli (ASDC and INAF/OAR), P. Giommi (ASDC), L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 1 Mar 2017; 13:12 UT
Credential Certification: Giovanni Piano (giovanni.piano@iaps.inaf.it)

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

Referred to by ATel #: 10179, 10243, 10257, 10274

The AGILE-GRID detector is revealing gamma ray emission above 100 MeV from a source positionally consistent with the microquasar Cygnus X-3. Integrating from 2017-02-27 UT 03:00:00 to 2017-03-01 UT 03:00:00 (MJD 57811.125 - 57813.125), a preliminary multi-source likelihood analysis detects a gamma-ray flux F(>100 MeV) = (3 +/- 1) x 10^-6 photons/cm^2/s with a detection significance near 4 sigma.

Cyg X-3 was recently detected (MJD 57798- 57801) in high-energy gamma-rays by Fermi-LAT (ATel #10126). We notice that Cygnus X-3 is currently moving out from a very low state in hard X-rays (Swift/BAT, 15-50 keV; http://swift.gsfc.nasa.gov/results/transients/CygX-3/ ). As previously detected, this X-ray spectral transitions with contemporaneous gamma-ray flares 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)). Therefore, Cyg X-3 might produce radio flares in the next few days.

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