Open AccessThe identification of an optical counterpart to the super‐Eddington X‐ray source NGC 5204 X‐1
Author(s) -
Roberts T.P.,
Goad M.R.,
Ward M.J.,
Warwick R.S.,
O'Brien P.T.,
Lira P.,
Hands A.D.P.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04659.x
Subject(s) - physics , astrophysics , neutron star , luminosity , telescope , eddington luminosity , binary number , astronomy , galaxy , arithmetic , mathematics
We report the identification of a possible optical counterpart to the super‐Eddington X‐ray source NGC 5204 X‐1. New Chandra data show that the X‐ray source is point‐like, with a luminosity of 5.2×10 39 erg s −1 (0.5–8 keV) . It displays medium‐ and long‐term X‐ray variability in observations spanning a period of 20 yr. The accurate Chandra position allows us to identify a blue optical continuum source (m v =19.7) at the position of NGC 5204 X‐1, using newly obtained optical data from the INTEGRAL instrument on the William Herschel Telescope. The X‐ray and optical source properties are consistent with the scenario in which we are observing the beamed X‐ray emission of a high‐mass X‐ray binary in NGC 5204, composed of an O star with either a black hole or neutron star companion.