2003/10/26 by L. Zampieri, P. Mucciarelli, R. Falomo +5 · 1 citation
Physics and Astronomy · #Accretion (finance) #Adaptive optics and wavefront sensing #Art #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Black hole (networking) #EPIC #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Literature #Luminosity #Physics #ROSAT #astro-ph
paper · pdf · doi:10.1086/381541
published as Astrophys.J. 603 (2004) 523-530 · 12 pages, 6 figures; submitted to The Astrophysical Journal
arxiv created 2003/10/26 · openalex publication_date 2004/03/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present new optical and Chandra observations of the field containing the ultraluminous X-ray source NGC 1313 X-2. On an ESO 3.6 m image, the Chandra error box embraces an R = 21.6 pointlike object and excludes a previously proposed optical counterpart. The resulting X-ray/optical flux ratio of NGC 1313 X-2 is ~500. The value of f X / f opt , the X-ray variability history, and the spectral distribution derived from a reanalysis of the ROSAT , ASCA , and XMM-Newton data indicate a luminous X-ray binary in NGC 1313 as a likely explanation for NGC 1313 X-2. If the X-ray soft component observed in the XMM-Newton EPIC spectrum originates from an accretion disk, the inferred mass of the compact remnant is ≈100 M ☉ , making it an intermediate-mass black hole. The derived optical luminosity ( L ≈ 10 5 L ☉ ) is consistent with that of a ≈15-20 M ☉ companion. The properties of the environment of NGC 1313 X-2 are briefly discussed.