INTEGRAL AND SWIFT OBSERVATIONS OF THE Be X-RAY BINARY 4U 1036–56 (RX J1037.5–5647) AND ITS POSSIBLE RELATION WITH γ-RAY TRANSIENTS

We present timing, spectral, and long-term temporal analysis of the high-mass X-ray binary 4U 1036–56 using INTEGRAL and Swift observations. We show that it is a weak hard X-ray source spending a major fraction of the time in quiescence and only occasionally characterized by X-ray outbursts. The outburst activity we report here lasts several days, with a dynamic range spanned by the luminosity in quiescence and in outburst as high as ∼30. We report the detection of pulse period at 854.75 ± 4.39 s during an outburst, which is consistent with previous measurements. Finally, we analyze the possibility of the association of 4U 1036–56 with the unidentified transient γ-ray sources AGL J1037–5708 and GRO J1036–55, as prompted by its positional correlation.