• Record: found
  • Abstract: found
  • Article: found
Is Open Access

A powerful and highly variable off-nuclear X-ray source in the composite starburst/Seyfert 2 galaxy NGC 4945

, ,



Read Bookmark
      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


      We report on a powerful and variable off-nuclear X-ray source in the nearby spiral galaxy NGC 4945. Two ROSAT PSPC observations show the source to brighten in 0.5--2.0 keV flux by a factor of about 9 on a time-scale of 11 months or less. It is seen by ASCA about one month after the second PSPC pointing, and is seen to have dimmed by a factor of > 7 in a ROSAT HRI pointing about one year after the second PSPC pointing. Its maximum observed 0.8--2.5 keV luminosity is about 8E38 erg/s, making it brighter than any known persistent X-ray binary in the Milky Way. Its total X-ray luminosity is probably larger than 1.2E39 erg/s. The observed variability argues against a superbubble interpretation, and the off-nuclear position argues against a low-luminosity active galactic nucleus. The source is therefore probably either an ultra-powerful X-ray binary or an ultra-powerful supernova remnant. Optical monitoring has not identified any supernovae in NGC 4945 during the time of the X-ray observations, and any supernova would have had to have been either very highly absorbed or intrinsically optically faint.

      Related collections

      Author and article information

      Custom metadata
      5 pages, uuencoded compressed tar file, MNRAS in press
      ScienceOpen disciplines:


      Comment on this article

      Register to benefit from advanced discovery features on more than 34,000,000 articles

      Already registered?