Unveiling the nature of IGR J16493-4348 with IR spectroscopy

TL;DR

This study uses IR spectroscopy to classify the optical counterpart of IGR J16493-4348 as a B0.5-1 supergiant, aiding understanding of its nature as a high-mass X-ray binary.

Contribution

It extends previous spectral analyses to IGR J16493-4348, providing its classification and insights into its interstellar and circumstellar extinction properties.

Findings

Classified the source as B0.5-1 supergiant

Estimated interstellar extinction and compared with X-ray data

Discussed absorption components related to circumstellar environment

Abstract

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is discovering a large number of new hard X-ray sources, many of them being HMXBs. The identification and spectral characterization of their optical/infrared counterparts is a necessary step in undertaking a detailed study of these systems. In a previous paper, we presented spectral analyses and classifications of six newly discovered INTEGRAL sources. In this paper, we extend the analysis to IGR J16493-4348. We used the ESO/VLT ISAAC spectrograph to observe the proposed IR counterpart to the source, obtaining a Ks medium-resolution spectrum (R = 500) with a signal-to-noise ratio (S/N) >150. We classified the source by comparing with published atlases. We spectrally classified the source as a B0.5-1 supergiant and estimated its interstellar extinction. We compared the extinction derived from X-ray data with effective interstellar extinction obtained from our data, discussing the absorption component associated with the circumstellar environment.