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The Power Spectrum of the Lyman-$\alpha$ Forest at z < 0.5
- Publication Year :
- 2018
-
Abstract
- We present new measurements of the flux power-spectrum P(k) of the $z<0.5$ HI Lyman-$\alpha$ forest spanning scales k ~ 0.001-0.1 s/km. These results were derived from 65 far ultraviolet quasar spectra (resolution R~18000) observed with the Cosmic Origin Spectrograph (COS) on board the Hubble Space Telescope. The analysis required careful masking of all contaminating, coincident absorption from HI and metal-line transitions of the Galactic interstellar medium and intervening absorbers as well as proper treatment of the complex COS line-spread function. From the P(k) measurements, we estimate the HI photoionization rate ($\Gamma_{\rm HI}$) in the z<0.5 intergalactic medium. Our results confirm most of the previous $\Gamma_{\rm HI}$ estimates. We conclude that previous concerns of a photon underproduction crisis are now resolved by demonstrating that the measured $\Gamma_{\rm HI}$ can be accounted for by ultraviolet emission from quasars alone. In a companion paper, we will present constraints on the thermal state of the $z<0.5$ intergalactic medium from the P(k) measurements presented here.<br />Comment: 15 pages, 8 figures, Accepted for publication in MNRAS
- Subjects :
- Astrophysics - Cosmology and Nongalactic Astrophysics
Subjects
Details
- Database :
- arXiv
- Publication Type :
- Report
- Accession number :
- edsarx.1808.05605
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1093/mnras/stz344