2004/04/21 by David A. Buote, Fabrizio Brighenti, William G. Mathews
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/422097
published as Astrophys.J. 607 (2004) L91-L94 · 4 pages, 2 figures, To Appear in ApJ Letters
arxiv created 2004/04/21 · openalex publication_date 2004/04/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
A new XMM observation of the outer regions of the galaxy group NGC 5044 indicates hot gas iron abundances of only Z Fe / Z ☉ ~ 0.15 between r = 0.2 r vir and 0.4 r vir . While the total baryon mass within the virial radius may be close to the cosmic mean value observed in rich clusters, the ratio of total iron mass to optical light in NGC 5044 is about 3 times lower than that in rich clusters. The remarkably low iron abundance over a large volume of the intergroup gas in the outer regions of NGC 5044 cannot be easily understood in terms of the outflow of enriched gas in a group wind during its early history or by the long-term enrichment by the group member galaxies that currently occupy this region. It is possible that the stars in NGC 5044 did not produce iron with the same efficiency as in clusters, or that the iron resides in nonluminous clouds or stars, or that the entropy of the iron-enriched gas created in early galactic starburst winds was too high to penetrate the group gas of lower entropy.