The influence of metagalactic ultra-violet background fluctuations on the high-redshift Ly$\alpha$ forest

Abstract

Under the assumption that galaxies and Quasi-Stellar Objects (QSOs) dominate the metagalactic ultra-violet (UV) background, it is shown that at high redshifts fluctuations in the UV background are dominated by QSO shot noise and have an auto-correlation length of a few to several comoving Mpcs, depending on the bright end of the QSO luminosity function. The correlations create long range spatial coherence in the neutral hydrogen fraction. Using a semi-analytic model, it is demonstrated that the coherence may account for the broad distribution in effective optical depths measured in the Ly$\alpha$ forest spectra of background QSOs, for line-of-sight segments of comoving length $50h^{-1}$ Mpc at redshifts $5<z<6$. Capturing the fluctuations in a numerical simulation requires a comoving box size of $\sim 1h^{-1}$ Gpc, although a box half this size may be adequate if sufficient random realizations of the QSO population are performed.

11 pages, 9 figures. Accepted for publication in MNRAS

References in corpus (13)

• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• An Observational Determination of the Bolometric Quasar Luminosity Function
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Conditions for Reionizing the Universe with A Low Galaxy Ionizing Photon Escape Fraction
• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• First Season MWA EoR Power Spectrum Results at Redshift 7
• Clustering of quasars in SDSS-IV eBOSS : study of potential systematics and bias determination
• Glimpsing through the high redshift neutral hydrogen fog
• The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from z-dropout Galaxies
• The VLT LBG Redshift Survey - III. The clustering and dynamics of Lyman-break galaxies at z ~ 3
• Constraining the Tail-End of Reionization Using Lyman-$\alpha$ Transmission Spikes

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