Helium Reionization Simulations. I. Modeling Quasars as Radiation Sources

Abstract

We introduce a new project to understand helium reionization using fully coupled $N$-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium (IGM) as a result of reionization and make predictions about the Lyman-$\alpha$ forest and baryon temperature-density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models include two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function (QLF) given a halo catalog from an $N$-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurements from BOSS, we find that the characteristic mass of quasar hosts is $M_h\sim 2.5\times 10^{12}{M}_{\odot }$ $h^{-1}$ for the lightbulb model, and $M_h\sim 2.3\times 10^{12}{M}_{\odot }$ $h^{-1}$ for the exponential model. In the exponential model, the peak quasar luminosity for a given halo mass is larger than that in the lightbulb model, typically by a factor of 1.5-2. The effective lifetime for quasars in the lightbulb model is 59 Myr, and in the exponential case, the effective time constant is about 15 Myr. We include semi-analytic calculations of helium reionization, and discuss how to include these quasars as sources of ionizing radiation for full hydrodynamics with radiative transfer simulations in order to study helium reionization.

18 pages, 12 figures. Updated for ApJ version. For a video summary of the paper, visit: https://www.youtube.com/watch?v=sGGtjetxjnk

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Cited by in corpus (19)

• Evolution of the AGN UV luminosity function from redshift 7.5
• New synthesis models of consistent extragalactic background light over cosmic time
• The ASTRID Simulation: Galaxy Formation and Reionization
• The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS
• The accuracy of semi-numerical reionization models in comparison with radiative transfer simulations
• The Evolution of the HeII-Ionizing Background at Redshifts 2.3<z<3.8 Inferred from a Statistical Sample of 24 HST/COS HeII Ly$\alpha$ Absorption Spectra
• Constraints on QSO emissivity using H I and He II Lyman alpha forest
• Helium Reionization Simulations. II. Signatures of Quasar Activity on the IGM
• Evidence for Short $\sim 1$ Myr Lifetimes from the He II Proximity Zones of $z\sim 4$ Quasars
• Effect of non-equilibrium ionization on derived physical conditions of the high-$z$ intergalactic medium
• The Accretion History of AGN: A Newly Defined Population of Cold Quasars
• Helium Reionization Simulations. III. The Helium Lyman-$\alpha$ Forest
• SCORCH. III. Analytical Models of Reionization with Varying Clumping Factors
• Constraints On Duty Cycles Of Quasars At Z $\sim$ 6
• Probing the high-z IGM with the hyperfine transition of ${}^3$He${}^{+}$
• Accretion History of AGN: Estimating the Host Galaxy Properties in X-ray Luminous AGN from z=0-3
• Reconstructing patchy helium reionization using the cosmic microwave background and large-scale structure
• Simulating the epoch of Helium Reionization in photon-conserving semi-numerical code SCRIPT
• Measuring photo-ionization rate and mean free path of HeII ionizing photons at $2.5\le z\le 3.6$: Evidence for late and rapid HeII reionization Part-II