Munar-Adrover, PerePereMunar-AdroverSabatini, S.S.SabatiniPiano, GiovanniGiovanniPianoLucarelli, FabrizioFabrizioLucarelliVerrecchia, FrancescoFrancescoVerrecchiaPittori, CarlottaCarlottaPittori2020-09-172020-09-172016-10-01https://hdl.handle.net/20.500.13025/4778The Astrophysical Journal, Volume 829, Issue 2, article id. 101, <NUMPAGES>8</NUMPAGES> pp. (2016).AGILE discovered the transient source AGL J2241+4454 in 2010, which triggered the study of the associated field allowing for the discovery of the first Be/black hole binary system MWC 656. This binary was suggested to be the counterpart of AGL J2241+4454, but this association is still not robust. In this work we explore the archival AGILE and Fermi/Large Area Telescope (LAT) data to find more transient events compatible with AGL J2241+4454 and address the possibility to link them to the accretion/ejection processes of MWC 656. We found a total of nine other transient events with AGILE compatible with the position of AGL J2241+4454, besides the 2010 one. We folded these events with the period of the binary system and we could not associate the gamma-ray activity with any particular orbital phase. By stacking the 10 transient events we obtained a spectrum that extends between 100 MeV and 1 GeV, and we fitted it with a power law with a photon index {{Gamma }}=2.3+/- 0.2. We searched the Fermi/LAT data in order to complement the gamma-ray information provided by AGILE but no significant results arose. To investigate this apparent contradiction between these telescopes, we studied the exposure of the field of AGL J2241+4454 in both instruments, and found significant differences. In particular, AGILE exposed, for a longer time and at a lower off-axis angular distance, the field of AGL J2241+4454. This fact, together with the energy-dependent sensitivity of both instruments, and the soft spectrum found in the stacking analysis, might explain why AGILE observed the transient events not seen by Fermi/LAT.binaries generalgamma-rays starsstars black holesstars emission-lineBestars individual MWC 656X-rays binaries10.3847/0004-637X/829/2/101http://adsabs.harvard.edu/abs/2016ApJ...829..101M2016ApJ...829..101M