The Local Ly-alpha Forest IV: STIS G140M Spectra and Results on the Distribution and Baryon Content of HI Absorbers

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dc.creatorPenton, Steven V.
dc.creatorStocke, John T.
dc.creatorShull, J. Michael
dc.date2004-01-05
dc.date.accessioned2026-07-07T11:29:19Z
dc.date.available2026-07-07T11:29:19Z
dc.descriptionWe present HST STIS/G140M spectra of 15 extragalactic targets, which we combine with GHRS/G160M data to examine the statistical properties of the low-z Ly-alpha forest. We evaluate the physical properties of these Ly-alpha absorbers and compare them to their high-z counterparts. We determine that the warm, photoionized IGM contains 29+/-4% of the total baryon inventory at z = 0. We derive the distribution in column density, N_HI^(1.65+/-0.07) for 12.5 < log [N_HI] < 14.5, breaking to a flatter slope above log [N_HI] > 14.5. The slowing of the number density evolution of high-W Ly-alpha clouds is not as great as previously measured, and the break to slower evolution may occur later than previously suggested (z~1.0 rather than 1.6). We find a 7.2sigma excess in the two-point correlation function (TPCF) of Ly-alpha absorbers for velocity separations less than 260 km/s, which is exclusively due to the higher column density clouds. From our previous result that higher column density Ly-alpha clouds cluster more strongly with galaxies, this TPCF suggests a physical difference between the higher and lower column density clouds in our sample.
dc.description71 pages, 6 tables, 26 EPS figures, to appear in ApJ Supplement
dc.identifierhttps://arxiv.org/abs/astro-ph/0401036
dc.identifierhttp://arxiv.org/abs/astro-ph/0401036
dc.identifierAstrophys.J.Suppl.152:29,2004
dc.identifierdoi:10.1086/382877
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/196673
dc.subjectAstrophysics
dc.titleThe Local Ly-alpha Forest IV: STIS G140M Spectra and Results on the Distribution and Baryon Content of HI Absorbers
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