4U 1344-60: a bright intermediate Seyfert galaxy at z = 0.012 with a relativistic Fe Kα emission line

Abstract

We present analysis of the optical and X-ray spectra of the low Galactic latitude bright (F_2-10 = 3.6 × 10^-11 erg cm^-2 s^-1) source 4U 1344-60. On the basis of the optical data we propose to classify 4U 1344-60 as an intermediate type Seyfert galaxy and we measure a value of z = 0.012±0.001 for its redshift. From the XMM-Newton observation we find that the overall X-ray spectral shape of 4U 1344-60 is complex and can be described by a power-law continuum (Γ≈ 1.55) obscured by two neutral absorption components (N_H^f ~ 10²² cm^-2 and N_H^p ~ 4 × 10²² cm^-2), the latter covering only the ~50% of the primary X-ray source. The X-ray data therefore lend support to our classification of 4U 1344-60. It exhibits a broad and skewed Fe Kα line at ~6.4 keV, which suggests the existence of an accretion disk that is able to reprocess the primary continuum down to a few gravitational radii. Such a line represents one of the clearest examples of a relativistic line observed by XMM-Newton so far. Our analysis has also revealed the marginal presence of two narrow line-like emission features at ~4.9 and ~5.2 keV.