2012A&A...546A.125M

We report on a series of outbursts of the high-mass X-ray binary XTE J1946+274 in 2010/2011 observed with INTEGRAL, RXTE, and Swift. We discuss possible mechanisms resulting in the extraordinary outburst behavior of this source. The X-ray spectra can be described by standard phenomenological models, enhanced by an absorption feature of unknown origin at about 10keV and a narrow iron Kα fluorescence line at 6.4keV, which are variable in flux and pulse phase. We find possible evidence for a cyclotron resonance scattering feature at about 25keV at the 93% level. The presence of a strong cyclotron line at 35keV seen in data from the source's 1998 outburst that was confirmed by a reanalysis of these data can be excluded. This result indicates that the cyclotron line feature in XTE J1946+274 is variable between individual outbursts.