The contribution of galaxies to the UV ionising background and the evolution of the Lyman forest

Details The contribution of galaxies to the UV ionising background and the evolution of the Lyman forest The contribution of galaxies to the UV ionising background and the evolution of the Lyman forest

2001-06-28

arxiv.org/abs/astro-ph/0106526v1

Astronomy and Astrophysics

Astrophysics

9 pages, A&A accepted

Scientific paper

10.1051/0004-6361:20010944

We have modelled the evolution of the number of Ly_alpha absorbers with redshift, resulting from the evolution of the ionising background and the Hubble expansion. The contribution of quasars (QSOs) and galaxies to the HI-ionising UV background has been estimated. The QSOs emissivity is derived from recent fits of their luminosity function. The galaxy emissivity is computed using a stellar population synthesis model, with a star-formation history scaled on observations of faint galaxies at lambda <= 1500 A. We allow for three values of the fraction of ionising photons that can escape the interstellar medium, f_esc=0.05, 0.1 and 0.4. The Intergalactic Medium is modelled as made of purely-absorbing clouds with the distribution in redshift and column density obtained from QSOs absorption lines. For the adopted values of f_esc, the contribution of galaxies to the ionising UV background is comparable or greater than that of QSOs. Accounting for the contribution of clouds to the UV emission, all models with f_esc <~ 0.1 provide an ionising flux compatible with local and high-z determination, including those with a pure QSOs background. The observed z ~ 1 break in the evolution can be better explained by a dominant contribution from galaxies. We find that models in Lambda-cosmology with Omega_matter=0.3, Omega_Lambda=0.7 describe the flat absorbers evolution for z <~ 1.0 better than models for Omega_matter=1.0.

Affiliated with

Also associated with

No associations

Rating

The contribution of galaxies to the UV ionising background and the evolution of the Lyman forest 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 contribution of galaxies to the UV ionising background and the evolution of the Lyman forest, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The contribution of galaxies to the UV ionising background and the evolution of the Lyman forest will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-123586