The nature of the X-ray binary IGR J19294+1816from INTEGRAL, RXTE, and Swiftobservations

We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swiftof the recently discovered INTEGRALsource IGR J19294+1816. The Swift/XRT data allow us to refine the position of the source to ${\mathrm{RA}}_{\mathrm{J}2000}$= $19^{\mathrm h} 29^{\mathrm m} 55.9^{\mathrm s}$${\mathrm{Dec}}_{\mathrm{J}2000}$= +18° 18′38.4″ (±3.5″), which in turn permits us to identify a candidate infrared counterpart. The Swiftand RXTEspectra are well fitted with absorbed power laws with hard (Γ~ 1) photon indices. During the longest Swiftobservation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong ($P = 40$%) pulsation at 12.43781 (±0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+1816being an HMXB with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (~$2000{-}3000$s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implications of IGR J19294+1816being an SFXT.