The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background

Details The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background

1996-12-31

arxiv.org/abs/astro-ph/9612245v1

Astrophys.J.489:7-20,1997

Astronomy and Astrophysics

Astrophysics

35 pages latex (uses aaspp4 and psfig.sty), 10 postscript figures; submitted to ApJ. The complete paper can also be retrieved

Scientific paper

10.1086/304765

We have measured the distribution function of the flux decrement caused by Lyman alpha forest absorption in a new sample of high resolution QSO spectra. The observations are compared to the results from two simulations of the Lya forest: an Eulerian Lambda-CDM model, and an SPH standard CDM model. Good agreement between the shapes of simulated and observed distributions is achieved by globally scaling the optical depth to match the mean flux decrements. This procedure amounts to a measurement of the parameter Omega_b^2 h^3 / Gamma (where Omega_b is the baryonic matter density and Gamma is the HI ionization rate). Estimating a lower limit Gamma > 7 10^{-13} s^{-1} from the abundance of known QSOs, we derive a lower limit to the baryon density, Omega_b h^2>0.021(0.017) for the Lambda-CDM (SCDM) model. In both cases the large values are inconsistent with some recent D/H determinations (Rugers & Hogan 1996a,b), favoring a low deuterium abundance as reported by Tytler, Fan & Burles (1996). Adopting a fixed Omega_b, we can determine the evolution of the ionizing radiation field. Our models predict the intensity to be approximately constant with redshift, consistent with the assumption that the ionizing background is produced by known quasars for z < 3. However, additional sources of ionizing photons are required at higher redshift.

Affiliated with

Also associated with

No associations

Rating

The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Opacity of the Lyman Alpha Forest and Implications for Omega_{baryon} and the Ionizing Background will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-512241