He ii REIONIZATION AND ITS EFFECT ON THE INTERGALACTIC MEDIUM

By M. McQuinn, A. Lidz, M. Zaldarriaga, L. Hernquist, P. Hopkins, S. Dutta, C. Faucher-Giguére. 2008

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Observations of the intergalactic medium (IGM) suggest that quasars reionize He ii in the IGM at z ≈ 3. We have run a set of 190 and 430 comoving Mpc simulations of He ii being reionized by quasars to develop an understanding of the nature of He ii reionization and its potential impact on observables. We find that He ii reionization heats regions in the IGM by as much as 25, 000 K above the temperature that is expected otherwise, with the volume-averaged temperature increasing by ∼12, 000 K and with large temperature fluctuations on ∼50 Mpc scales. Much of this heating occurs far from quasars by photons with long mean free path. We find a temperature–density equation of state of γ − 1 ≈ 0.3 during He ii reionization, but with a wide dispersion in this relation having σT ∼ 104 K. He ii reionization by the observed population of quasars cannot produce an inverted relation (γ − 1 < 0). Our simulations are consistent with the observed evolution in the mean transmission of the He ii Lyα forest. We argue that the heat input from He ii reionization is unable to cause the observed depression at z ≈ 3.2 in the H i Lyα forest opacity as has been suggested. We investigate how uncertainties in the properties of QSOs and of He ii Lyman limit systems influence our predictions.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/274ecb73cc4a320c99f95d19aa089ed26687b96a

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Citations in the corpus

New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization (2013, background): “In a patchy and extended helium reionization (e.g., Becker et al. 2011), the globally-averaged temperature-density relation is also unlikely to flatten dramatically (McQuinn et al. 2009; Compostella et al. 2013), although it may be flat or inverted locally.”
Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium (2018, background): “…recombination rate of He III, the double ionization of helium is expected to be completed by hard UV-emitting quasars around the apparent peak of their activity, at ' 2.5 (e.g., McQuinn et al. 2009; Haardt & Madau 2012, hereinafter HM12), at much later times than the reionization of H I and He I .”
Detection of extended He II reionization in the temperature evolution of the intergalactic medium (2010, methodology): “…that growing He iii bubbles around QSOs introduce spatial fluctuations in both ionization and temperature (Sokasian et al. 2002; Gleser et al. 2005; Lai et al. 2006; Paschos et al. 2007; Furlanetto & Oh 2008), even if these are partially damped by radiative transfer effects (McQuinn et al. 2009).”
A model for cosmological simulations of galaxy formation physics: multi-epoch validation (2013, methodology): “…the model was calibrated to satisfy the measured mean transmission of the Ly-alpha forest at intermediate redshifts z = 2−4.2 (Faucher-Giguère et al. 2008a,b), published HeII to HI column density ratios, HeII reionisation by z ∼ 3 (McQuinn et al. 2009), and complete HI reionisation by z = 6.”
Evolution of the AGN UV luminosity function from redshift 7.5 (2018, methodology): “…Lyman limit systems are ap- 8 La Plante & Trac (2016) erroneously varied the z > 3.5 QLF parameters independently, neglecting their covariance and the survey data. proximately captured with sub-grid filtering methods (McQuinn et al. 2009) or with adaptive mesh refinement (Compostella et al. 2014).”
RADIATIVE TRANSFER IN A CLUMPY UNIVERSE. IV. NEW SYNTHESIS MODELS OF THE COSMIC UV/X-RAY BACKGROUND (2011, background): “…recombination rate of He III, the double ionization of helium is expected to be completed by hard UV-emitting quasars around the peak of their activity at z ≈ 2.5 (e.g., Madau & Meiksin 1994; Sokasian, Abel, & Hernquist 2002; McQuinn et al. 2009), much later than the reionization of H I and He I.”
Modified Gravity-GADGET: A new code for cosmological hydrodynamical simulations of modified gravity models (2013, background): “…in the peak temperature, may, however, be rather small compared to uncertainties in the heating efficiency due to helium II reionization (see e.g. McQuinn et al. 2009) or the effects of a recently suggested additional heating of the IGM by TeV-blazars (Broderick et al. 2012; Puchwein et al.…”
New Constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-$\alpha$ forest data (2017, background): “The bounds for γ at each redshift are physically motivated for the time of HeII reionization [1, 48].”
COSMOLOGICAL IMPLICATIONS OF FAST RADIO BURST/GAMMA-RAY BURST ASSOCIATIONS (2013, background): “(13), one gets ΩbfIGM= 8πGmpDMIGM 3cH0 / ∫ z 0 [ 34y1χe,H(z) + 1 8y2χe,He(z)](1 + z)dz [Ωm(1 + z)3 +ΩΛ]1/2 (14) Studies suggest that H is essentially fully ionized at z < 6 (Fan et al. 2006), and He is essentially fully ionized at z < 2 (McQuinn et al. 2009).”
Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, methodology): “7 He II Lyα forest have been used to place limits of QHe II10% at the cosmic mean density, which implies that He II reionization was likely still in progress at z∼2.7 (McQuinn 2009; Shull et al. 2010; Syphers & Shull 2014).”
The Evolution of the Intergalactic Medium (2015, background): “During He ii reionization by quasars (which is discussed in more detail in § 2.5), He iii bubbles are blown around quasars and the IGM is additionally heated by (5− 10)× 103K (Furlanetto & Oh 2008; McQuinn et al. 2009; Compostella, Cantalupo & Porciani 2013).”
The first ultraviolet quasar-stacked spectrum at z ≃ 2.4 from WFC3 (2015, background): “…stack at z 2.4 from WFC3 4205 et al. 2014), they are likely the only sources responsible for the reionization of He II at z ∼ 3 (Miralda-Escudé, Haehnelt & Rees 2000; Faucher-Giguère et al. 2008; Furlanetto 2009; McQuinn et al. 2009; Haardt & Madau 2012; Compostella, Cantalupo & Porciani 2013).”
COSMIC REIONIZATION AFTER PLANCK: COULD QUASARS DO IT ALL? (2015, background): “…rather than complete Gunn-Peterson absorption at higher redshifts, recent observations have revelead hightransmission regions out to z = 3.5 (Worseck et al. 2015), in conflict with numerical models of He II reionization driven by luminous quasars (McQuinn et al. 2009; Compostella et al. 2013).”