The Local Lyα Forest. IV. Space Telescope Imaging Spectrograph G140M Spectra and Results on the Distribution and Baryon Content of H i Absorbers | Zendy

Steven V. Penton | Zendy; John T. Stocke | Zendy; J. Michael Shull | Zendy

Open Access

The Local Lyα Forest. IV. Space Telescope Imaging Spectrograph G140M Spectra and Results on the Distribution and Baryon Content of H i Absorbers

Author(s) -

Steven V. Penton,

John T. Stocke,

J. Michael Shull

Publication year - 2004

Publication title -

the astrophysical journal supplement series

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 3.546

H-Index - 277

eISSN - 1538-4365

pISSN - 0067-0049

DOI - 10.1086/382877

Subject(s) - physics , redshift , astrophysics , quasar , spectral line , spectrograph , intergalactic medium , baryon , extrapolation , number density , lyman alpha forest , hubble space telescope , space telescope imaging spectrograph , equivalent width , astronomy , emission spectrum , galaxy , statistics , mathematics

We present HST STIS/G140M spectra of 15 extragalactic targets, which wecombine with GHRS/G160M data to examine the statistical properties of the low-zLy-alpha forest. We evaluate the physical properties of these Ly-alphaabsorbers and compare them to their high-z counterparts. We determine that thewarm, 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 slowingof the number density evolution of high-W Ly-alpha clouds is not as great aspreviously measured, and the break to slower evolution may occur later thanpreviously suggested (z~1.0 rather than 1.6). We find a 7.2sigma excess in thetwo-point correlation function (TPCF) of Ly-alpha absorbers for velocityseparations less than 260 km/s, which is exclusively due to the higher columndensity clouds. From our previous result that higher column density Ly-alphaclouds cluster more strongly with galaxies, this TPCF suggests a physicaldifference between the higher and lower column density clouds in our sample.Comment: 71 pages, 6 tables, 26 EPS figures, to appear in ApJ Supplemen

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