The power spectrum of the Lyman-α Forest at z < 0.5. Issue 1 (17th February 2019)

• Record Type: Journal Article
• Authors: Khaire, Vikram; Walther, Michael; Hennawi, Joseph F; Oñorbe, Jose; Lukić, Zarija; Prochaska, J Xavier; Tripp, Todd M; Burchett, Joseph N; Rodriguez, Christian
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 486:Issue 1(2019)
• Page Start: 769
• Page End: 782
• Publication Date: 2019-02-17
• Subjects: (galaxies:) intergalactic medium -- quasars: general -- (cosmology:) diffuse radiation -- large -scale structure of Universe; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz344
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present new measurements of the flux power-spectrum P ( k ) of the z < 0.5 H i Lyman-α Forest spanning scales $k \sim 0.001\!-\!0.1\, \mathrm{s \, km}^{-1}$ . These results were derived from 65 far-ultraviolet quasar spectra (resolution $R \sim 18\, 000$ ) observed with the Cosmic Origin Spectrograph (COS) on board the Hubble Space Telescope . The analysis required careful masking of all contaminating, coincident absorption from H i 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 H i photoionization rate ($\Gamma _{\rm H\, {\small I}}$ ) in the z < 0.5 intergalactic medium. Our results confirm most of the previous $\Gamma _{\rm H\, {\small I}}$ estimates. We conclude that previous concerns of a photon underproduction crisis are now resolved by demonstrating that the measured $\Gamma _{\rm H\, {\small I}}$ 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.