The Evolution of the Intergalactic Medium Transmission to Redshift 6
Abstract
We have measured the transmission of the Lyα forest produced by neutral hydrogen scattering in the intergalactic medium between redshifts 2 and 6.3 using high signal-to-noise, high-resolution (R>=5000) observations of 50 quasars spread over the redshift range. We use a uniform set of 15 Å intervals covering Lyα, Lyβ, and Lyγ absorption regions to tabulate the forest transmission as a function of redshift. The transmitted fractions show a relatively smooth evolution over the entire range of redshifts, which can be modeled with a smoothly decreasing ionization rate. Previous claims of an abrupt change at z~6 appear in part to be a consequence of an incorrect conversion of Lyβ to Lyα optical depths. The tabulated transmissions can be used to calculate the colors of objects with a specified input spectrum as a function of redshift. We calculate the colors of a flat-fν galaxy with a large intrinsic continuum break as an important example.
- Publication:
-
The Astronomical Journal
- Pub Date:
- May 2004
- DOI:
- 10.1086/383561
- arXiv:
- arXiv:astro-ph/0402347
- Bibcode:
- 2004AJ....127.2598S
- Keywords:
-
- Cosmology: Early Universe;
- Galaxies: Formation;
- Galaxies: Intergalactic Medium;
- Galaxies: Quasars: Absorption Lines;
- Astrophysics
- E-Print:
- 32 pages, 6 figures, 6 tables