Loading...
Please wait, while we are loading the content...
Similar Documents
A Concordance Model of The Lyman-Alpha Forest at z = 1 . 95
| Content Provider | Semantic Scholar |
|---|---|
| Author | Jena, Tridivesh Norman, Michael L. Tytler, David Kirkman, David Suzuki, Nao Ângela Chapman Melis, Carl Paschos, Pascal O'Shea, Brian So, Geoffrey Lubin, Dan Wen-Ching |
| Copyright Year | 2006 |
| Abstract | We present 40 fully hydrodynamical numerical simulations of the intergalactic gas that gives rise to the Lyα forest. The simulation code, input and output files are available at http://www.cosmos.ucsd.edu/g̃so/index.html. For each simulation we predict the observable properties of the H I absorption in QSO spectra. We then find the sets of cosmological and astrophysical parameters that match the QSO spectra. We present our results as scaling relationships between input and output parameters. The input parameters include the main cosmological parameters Ωb, Ωm, ΩΛ, H0 and σ8; and two astrophysical parameters γ912 and X228. The parameter γ912 controls the rate of ionization of H I, He I and He II and is equivalent to the intensity of the UV background. The second parameter X228 controls the rate of heating from the photoionization of He II and can be related to the shape of the UVB at λ < 228 Å. We show how these input parameters; especially σ8, γ912 and X228; effect the output parameters that we measure in simulated spectra. These parameters are the mean flux F̄ , a measure of the most common Lyα line width (b-value) bσ, and the 1D power spectrum of the flux on scales from 0.01 – 0.1 s/km. We compare the simulation output to data from Kim et al. (2004) and Tytler et al. (2004) and we give a new measurement of the flux power from HIRES and UVES spectra for the low density IGM alone at z = 1.95. We find that simulations with a wide variety of σ8 values, from at least 0.8 – 1.1, can fit the small scale flux power and b-values when we adjust X228 to compensate for the σ8 change. We can also use γ912 to adjust the H I ionization rate to simultaneously match the mean flux. When we examine only the mean flux, b-values and small scale flux power we can not readily break the strong degeneracy between σ8 and X228. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://cns.bu.edu/~achapman/LymanAlpha.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
