Chandra grating spectroscopy of the Be/X-ray binary 1A 0535+262

Abstract

We present Chandra HETGS spectroscopy of the Be/X-ray binary 1A 0535+262 obtained during the 2009/2010 giant outburst. These are the first CCD grating spectra of this type of system during a giant outburst. Our spectra reveal a number of lines including a narrow Fe Kα emission line with an FWHM of ∼5000 km s-1. For the first time, we detect the presence of a highly ionized outflow in a Be/X-ray binary. Assuming that the line is He-like Fe xxv, fits with a simple Gaussian imply an outflow velocity of ∼1500 km s-1. However, self-consistent photoionization modeling with xstar suggests that Fe xxiii-xxiv must also contribute. In this case, an outflow velocity of ∼3000 km s-1 is implied. These results are discussed in the context of accretion flow in Be-star, neutron star, and black hole X-ray binaries. © 2010. The American Astronomical Society.