Neutral atomic hydrogen (H I) gas evolution in field galaxies at z ∼ 0.1 and ∼0.2
Abstract
We measure the neutral atomic hydrogen (H I) gas content of field galaxies at intermediate redshifts of z ∼ 0.1 and ∼0.2 using hydrogen 21-cm emission lines observed with the Westerbork Synthesis Radio Telescope. In order to make high signal-to-noise ratio detections, an H I signal stacking technique is applied: H I emission spectra from multiple galaxies, optically selected by the second Canadian Network for Observational Cosmology redshift survey project, are co-added to measure the average H I mass of galaxies in the two redshift bins. We calculate the cosmic H I gas densities (ΩHI) at the two redshift regimes and compare those with measurements at other redshifts to investigate the global evolution of the H I gas density over cosmic time. From a total of 59 galaxies at z ∼ 0.1 we find ΩHI = (0.33 ± 0.05) × 10-3, and at z ∼ 0.2 we find ΩHI = (0.34 ± 0.09) × 10-3, based on 96 galaxies. These measurements help bridge the gap between high-z damped Lyman α observations and blind 21-cm surveys at z = 0. We find that our measurements of ΩHI at z ∼ 0.1 and ∼0.2 are consistent with the H I gas density at z ∼ 0 and that all measurements of ΩHI from 21-cm emission observations at z ≲ 0.2 are in agreement with no evolution of the H I gas content in galaxies during the last 2.4 Gyr.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2013
- DOI:
- 10.1093/mnras/stt1481
- arXiv:
- arXiv:1308.1462
- Bibcode:
- 2013MNRAS.435.2693R
- Keywords:
-
- galaxies: evolution;
- galaxies: ISM;
- radio lines: galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 14 pages, 9 figures, accepted by MNRAS