2003/05/27 by K. Heike, H. Awaki, Y. Misao +2 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/377090
published as Astrophys.J. 591 (2003) L99-L102 · 15 pages including 4 Postscript figures; accepted for publication in ApJL
arxiv created 2003/05/27 · openalex publication_date 2003/06/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
From the analysis of a ~100 ks Chandra observation of the dwarf starburst galaxy NGC 1569, we have found that the X-ray point sources CXOU 043048.1+645050 and CXOU 043048.6+645058 show significant time variability. During this observation, the X-ray flux of CXOU 043048.1+645050 increased by 10 times in only 2 × 10 4 s. Since the spectrum in its bright phase was fitted with a disk blackbody model with kT in ≈ 0.43 keV and the bolometric luminosity is L bol ≈ 10 38 ergs s -1 , this source is an X-ray binary with a stellar mass black hole. Since the spectrum in its faint phase was also fitted with a disk blackbody model, the time variability can be explained by a change of the accretion rate onto the black hole. The other variable source, CXOU 043048.6+645058, had a flat spectrum with a photon index of ~1.6. This source may be an X-ray binary with an X-ray luminosity of several times 10 37 ergs s -1 . In addition, three other weak sources showed possible time variability. Taking all of the variability into account may suggest an abundant population of compact X-ray sources in NGC 1569.