Abstract
We present an updated version of the so-called Madau model for the
attenuation by the intergalactic neutral hydrogen against the radiation from
distant objects. First, we derive a distribution function of the intergalactic
absorbers from the latest observational statistics of the Ly$\alpha$ forest,
Lyman limit systems, and damped Ly$\alpha$ systems. The distribution function
excellently reproduces the observed redshift evolutions of the Ly$\alpha$
depression and of the mean-free-path of the Lyman continuum simultaneously.
Then, we derive a set of the analytic functions which describe the mean
intergalactic attenuation curve for objects at $z>0.5$. Our new model predicts,
for some redshifts, more than 0.5--1 mag different attenuation magnitudes
through usual broad-band filters relative to the original Madau model. Such a
difference would cause uncertainty of the photometric redshift of 0.2, in
particular, at $z\simeq3$--4. Finally, we find a more than 0.5 mag
overestimation of the Lyman continuum attenuation in the original Madau model
at $z>3$, which causes a significant overcorrection against direct observations
of the Lyman continuum of galaxies.
Users
Please
log in to take part in the discussion (add own reviews or comments).