2004/01/19 by T. X. Thuan, F. E. Bauer, P. Papaderos +1 · 69 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Dwarf galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Metallicity #Physics #Stellar, planetary, and galactic studies #Universe #astro-ph
paper · pdf · doi:10.1086/382949
published in The Astrophysical Journal 606(1), 213-220 (IOP Publishing) · emulateapj.cls used, 7 pages, 7 figures + 1 table, accepted for publication in ApJ
arxiv created 2004/01/19 · openalex publication_date 2004/04/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present an X-ray study of the three most metal deficient blue compact dwarf (BCD) galaxies known in the local universe, based on deep Chandra observations of SBS 0335-052 (0.025 Z ☉ ), SBS 0335-052W (0.02 Z ☉ ), and I Zw 18 (0.02 Z ☉ ). All three are detected, with more than 90% of their X-ray emission arising from pointlike sources. The 0.5-10.0 keV luminosities of these point sources are in the range (1.3-8.5) × 10 39 ergs s -1 . We interpret them to be single or a collection of high-mass X-ray binaries, the luminosities of which may have been enhanced by the low metallicity of the gas. There are hints of faint extended diffuse X-ray emission in both SBS 0335-052 and I Zw 18, probably associated with the superbubbles visible in both BCDs. The spectrum of I Zw 18 shows an O VIII hydrogen-like emission line. The best spectral fit gives an O overabundance of the gas in the X-ray point source by a factor of ~7 with respect to the Sun, or a factor of ~350 with respect to the O abundance determined for the H II region.