Open AccessA concordance model of the Lyman α forest at z = 1.95
Author(s) -
Jena Tridivesh,
Norman Michael L.,
Tytler David,
Kirkman David,
Suzuki Nao,
Chapman Angela,
Melis Carl,
Paschos Pascal,
O'Shea Brian,
So Geoffrey,
Lubin Dan,
Lin WenChing,
Reimers Dieter,
Janknecht Eckardt,
Fechner Cora
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09095.x
Subject(s) - physics , quasar , astrophysics , spectral line , baryon , flux (metallurgy) , photoionization , ionization , metallicity , lyman alpha forest , galaxy , observable , redshift , astronomy , intergalactic medium , quantum mechanics , ion , materials science , metallurgy
We present 40 fully hydrodynamical numerical simulations of the intergalacticgas that gives rise to the Ly-alpha forest. We make artificial spectra fromeach and measure three output parameters: the mean flux, a measure of the mostcommon Ly-alpha line width (b-value), and the 1D power spectrum of the flux onscales from 0.01 - 0.1 s/km. We investigate how these output parameters arecorrelated with the input parameters that describe the simulations. These inputparameters include the main cosmological parameters; and two astrophysicalparameters gammah and gammahe. The parameter gammah controls the rate ofionization of H I, He I and He II while gammahe controls the rate of heating.We compare the output from the simulations to data from HIRES and UVES spectraand we give a new measurement of the flux power from these spectra at z=1.95.We find that simulations with a wide variety of sigma_8 values, from at least0.8 - 1.1, can fit the small scale flux power and b-values when we adjustgammahe to compensate for the sigma_8 change. We can also use gammah to adjustthe H I ionization rate to simultaneously match the mean flux. We derivescaling relations that give the output parameter values expected for a varietyof input parameters with errors of 2% for optical depth and 1.4% for b-balues.We can break the degeneracy between gammahe and sigma_8 using large scale poweror other data to fix sigma_8.Comment: Revised author lis