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Paper: QSO Absorption Line Constraints on Intra-group High-Velocity Clouds
Volume: 240, Gas and Galaxy Evolution: A Conference in Honor of the 20th Anniversary of the VLA
Page: 487
Authors: Charlton, J. C.; Churchill, C. W.; Rigby, J. R.
Abstract: We show that the number statistics of moderate redshift Mg II and Lyman limit absorbers may rule out the hypothesis that high-velocity clouds (HVCs) are infalling intra-group material. There cannot be a substantial population of large, intra-group clouds in groups at redshift z~ 0.5 because such clouds would contribute to the cross-section for Mg II and Lyman limit absorption. Luminous galaxies already account for nearly all of this absorption. The discrepancies between the Local Group HVC population and the statistics of Mg II and Lyman limit absorbers can be reconciled: 1) if most of the extragalactic HVC analogs are within 200 kpc of galaxies, and not at large throughout the groups; or 2) if the HVCs consist of dense pockets of HI such that they are detected through beam-smearing of 21 cm emission but not along typical pencil beam quasar line-of-sight samplings.
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