Near-infrared spectroscopy of 20 new Chandra sources in the Norma Arm

Abstract

We report on CTIO/NEWFIRM and CTIO/OSIRIS photometric and spectroscopic observations of 20 new X-ray (0.5-10 keV) emitters discovered in the Norma Arm Region Chandra Survey (NARCS). NEWFIRM photometry was obtained to pinpoint the near-infrared counterparts of NARCS sources, while OSIRIS spectroscopy was used to help identify 20 sources with possible high mass X-ray binary properties. We find that (1) two sources are WN8 Wolf-Rayet stars, maybe in colliding wind binaries, part of the massive star cluster Mercer 81; (2) two are emission-line stars, possibly in X-ray binaries, that exhibit near- and mid-infrared excesses either due to free-free emission from the decretion discs of Be stars or warm dust in the stellar winds of peculiar massive stars such as B[e] supergiants or luminous blue variables; (3) one is a B8-A3 IV-V star that could be in a quiescent high mass X-ray binary system; (4) two are cataclysmic variables including one intermediate polar; (5) three may be neutron star symbiotic binaries; (6) five are most likely white dwarf symbiotic binaries; and (7) five exhibit properties more consistent with isolated giant/dwarf stars. The possible detection of one to three high mass X-ray binaries is in good agreement with our predictions. However, our study illustrates the difficulty of clearly differentiating quiescent or intermediate X-ray luminosity systems from isolated massive stars, which may lead to an underestimation of the number of known high mass X-ray binaries.

17 pages, 14 figures, 7 tables. Accepted for publication in A&A

References in corpus (13)

• Binary interaction dominates the evolution of massive stars
• X-Ray Spectroscopy of Stars
• A census of the Wolf-Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy
• Probing clumpy stellar winds with a neutron star
• Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. I. The nature of the companion star
• Quantitative studies of the optical and UV spectra of Galactic early B supergiants I. Fundamental parameters
• Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. II. The environment of the companion star
• IGR J16194-2810: a new symbiotic X-ray binary
• Distribution of High-Mass X-ray Binaries in the Milky Way
• A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations
• Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane
• IGR J18483-0311: a new intermediate supergiant fast X-ray transient
• Spitzer IRS Spectroscopy of Intermediate Polars: Constraints on Mid-Infrared Cyclotron Emission

Cited by in corpus (5)

• The Norma Arm Region Chandra Survey: X-ray Populations in the Spiral Arms
• Galactic Sources Detected in the NuSTAR Serendipitous Survey
• Initial Results from NuSTAR Observations of the Norma Arm
• Identifying four $INTEGRAL$ sources in the Galactic Plane via VLT/optical and $XMM$-$Newton$/X-ray spectroscopy
• A First Look at the X-ray Population of the Young Massive Cluster VVV CL077