XMM-Newton discovery of very high obscuration in the candidate Supergiant Fast X-ray Transient AX J1714.1-3912
Date Issued
2022
Author(s)
Abstract
We have analysed an archival XMM-Newton EPIC observation that serendipitously
covered the sky position of a variable X-ray source AX J1714.1-3912, previously
suggested to be a Supergiant Fast X-ray Transient (SFXT). During the XMM-Newton
observation the source is variable on a timescale of hundred seconds and shows
two luminosity states, with a flaring activity followed by unflared emission,
with a variability amplitude of a factor of about 50. We have discovered an
intense iron emission line with a centroid energy of 6.4 keV in the power
law-like spectrum, modified by a large absorption (NH around 1e24 cm-2), never
observed before from this source. This X-ray spectrum is unusual for an SFXT,
but resembles the so-called "highly obscured sources", high mass X-ray binaries
(HMXBs) hosting an evolved B[e] supergiant companion (sgB[e]). This might
suggest that AX J1714.1-3912 is a new member of this rare type of HMXBs, which
includes IGR J16318-4848 and CI Camelopardalis. Increasing this small
population of sources would be remarkable, as they represent an interesting
short transition evolutionary stage in the evolution of massive binaries.
Nevertheless, AX J1714.1-3912 appears to share X-ray properties of both kinds
of HMXBs (SFXT vs sgB[e] HMXB). Therefore, further investigations of the
companion star are needed to disentangle the two hypothesis.
Volume
512
Issue
2
Start page
2929
Issn Identifier
0035-8711
Ads BibCode
2022MNRAS.512.2929S
Rights
open.access
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