1999/02/01 by M. Henriksen, Mark Henriksen, Sarah Cousineau +1 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/306690
published as Astrophys.J. 511 (1999) 595-611 · 40 pages, 6 jpg figures, ApJ (in press)
openalex publication_date 1999/02/01 · arxiv created 1999/03/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
Results are reported from the first survey of X-ray emission from galaxies in pairs. The sample consists of 52 pairs of galaxies from the Catalog of Paired Galaxies whose coordinates overlap the ROSAT Position Sensitive Proportional Counter pointed observations. The mean observed log l X for early-type pairs is 41.35±0.21, while the mean log l X predicted using the l X - l b relationship for isolated early-type galaxies is 42.10±0.19. With 95% confidence, the galaxies in pairs are underluminous in the X-ray, compared with isolated galaxies, for the same l b . A significant fraction of the mixed pair sample also appears similarly underluminous. A spatial analysis shows that the X-ray emission from pairs of both types typically has an extent of ~10-50 kpc, much smaller than the group intergalactic medium, and thus likely originates from the galaxies. CPG 564, the most X-ray luminous early-type pair, 4.7 × 10 42 ergs s -1 , is an exception. The extent of its X-ray emission, greater than 169 kpc, and HWHM, ~80 kpc, is comparable to that expected from an intergalactic medium. The sample shows only a weak correlation, ~81% confidence, between l X and l b , presumably due to variations in gas content within the galaxies. No correlation between l X and the pair velocity difference (Δ v ), separation (Δ r ), or far-infrared luminosity ( l fir ) is found, although the detection rate is low, 22%.