Concordance models of reionization: implications for faint galaxies and escape fraction evolution

By Michael Kuhlen, C. Faucher-Giguére. 2012

278 citations recorded by the source corpus.

Recent observations have constrained the galaxy UV luminosity function up to z~10. However, these observations alone allow for a wide range of reionization scenarios due to uncertainties in the abundance of faint galaxies and the escape fraction of ionizing photons. We show that requiring continuity with post-reionization (z ~10 from z=4 (where the best fit is 4%) to z=9; or 3) more likely, a hybrid solution in which undetected galaxies contribute significantly and f_esc increases more modestly. Models in which star formation is strongly suppressed in low-mass, reionization-epoch haloes of mass up to ~10^10 M_sun (e.g., owing to a metallicity dependence) are only allowed for extreme assumptions for the evolution of f_esc. However, variants of such models in which the suppression mass is reduced (e.g., assuming an earlier or higher metallicity floor) are in better agreement with the data. Concordance scenarios satisfying the available data predict a consistent redshift of 50% ionized fraction z_reion(50%) ~ 10. On the other hand, the duration of reionization is sensitive to the relative contribution of bright versus faint galaxies, with scenarios dominated by faint galaxies predicting a more extended reionization event. Scenarios relying too heavily on high-z dwarfs are disfavored by kinetic Sunyaev-Zeldovich measurements, which prefer a short reionization history.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5e59bab7f1883653d2fbadd57680b52a3c5042e9

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. Richard S. Ellis
4. R. Bouwens
5. P. Oesch
6. M. Franx
7. P. V. van Dokkum
8. J. Dunlop

In Electrical and Electronic Engineering

1. Richard S. Ellis
2. R. Bouwens
3. J. Dunlop
4. P. Oesch
5. D. Stark
6. G. Illingworth
7. R. McLure
8. I. Labbé

In Instrumentation

1. Richard S. Ellis
2. R. Bouwens
3. P. Hopkins
4. M. Franx
5. P. V. van Dokkum
6. P. Oesch
7. G. Illingworth
8. J. Dunlop

Citations in the corpus

• Signatures of X-rays in the early Universe (2012, background): “…(z ∼ 6– 10) seem unable to maintain an ionized Universe, baring an evolution in galaxy properties (for example, an increase with redshift in the fraction of ionizing photons capable of making it out of the galaxy; e.g. Mitra et al. 2012; Kuhlen & Faucher-Giguere 2012; Fontanot et al. 2012).”
• The origin and evolution of the galaxy mass–metallicity relation (2015, background): “Their main halos cover halo masses from 7.7× 108–5.6× 1010M at z = 6 and these galaxies are believed to contribute most to the cosmic reionization (e.g. Kuhlen & Faucher-Giguère 2012; Robertson et al. 2013).”
• Galaxy UV-luminosity function and reionization constraints on axion dark matter (2014, background): “We follow Kuhlen & Faucher-Giguère (2012) and define: γion(MUV ) ≡ 2× 1025 s−1(100.4(51.63−MUV )), (11) where the second term represents the AB relation of the galactic rest-frame UV (1500A◦) luminosity.”
• COSMIC REIONIZATION AFTER PLANCK: COULD QUASARS DO IT ALL? (2015, background): “…the Lyα opacity data can only be achieved by carefully tuning the escape fraction from star-forming galaxies to increase rapidly with lookback time, so as to compensate for the decline in the star formation activity towards early epochs (e.g., Haardt & Madau 2012; Kuhlen & Faucher-Giguère 2012).”
• The difficulty of getting high escape fractions of ionizing photons from high-redshift galaxies: A view from the FIRE cosmological simulations (2015, background): “Also, Kuhlen & Faucher-Giguère (2012) showed that even applying a cut off on UV magnitude at MUV =−13, the required escape fraction at z = 6 varies from 6%–30% when changing the faint-end slope of UVLF within observational uncertainties.”
• THE EVOLUTION OF THE GALAXY REST-FRAME ULTRAVIOLET LUMINOSITY FUNCTION OVER THE FIRST TWO BILLION YEARS (2014, background): “Kuhlen & Faucher-Giguère (2012) and Robertson et al. (2013) did similar analyses, folding in additional observables (e.g., the Lyα forest and CMB), and found that in order to complete reionization by z ~ 6, the luminosity function must extend much deeper than can presently be observed, and/or the…”
• CANDELS: THE CONTRIBUTION OF THE OBSERVED GALAXY POPULATION TO COSMIC REIONIZATION (2012, background): “Finally on Figure 6, we also show the concordance models of Kuhlen & Faucher-Giguère (2012), which present a picture of the reionization history of the universe consistent withthe Lyα forest,WMAPoptical depth, and the kSZ effect.”
• GALAXY PROPERTIES AND UV ESCAPE FRACTIONS DURING THE EPOCH OF REIONIZATION: RESULTS FROM THE RENAISSANCE SIMULATIONS (2016, methodology): “…relations or the UV galaxy LF can be used in semi-analytic reionization calculations (e.g., Robertson et al. 2010, 2013, 2015; Alvarez et al. 2012; Kuhlen & Faucher-Giguère 2012) to check whether galaxies can provide a sufficient amount of radiation to complete and sustain reionization by z∼6.”
• ARE ULTRA-FAINT GALAXIES AT z = 6–8 RESPONSIBLE FOR COSMIC REIONIZATION? COMBINED CONSTRAINTS FROM THE HUBBLE FRONTIER FIELDS CLUSTERS AND PARALLELS (2015, methodology): “The value of ξion is generally constrained using stellar population models of early galax- ies and the observed UV slope β of z > 6 galaxies (Bolton & Haehnelt 2007; Kuhlen & Faucher-Giguère 2012; Robertson et al. 2015).”
• ESCAPE FRACTION OF IONIZING PHOTONS DURING REIONIZATION: EFFECTS DUE TO SUPERNOVA FEEDBACK AND RUNAWAY OB STARS (2014, background): “Small halos at high redshift may make a more significant contribution to the Thompson optical depth (Wyithe & Cen 2007; Shull et al. 2012; Kuhlen & Faucher-Giguère 2012; Robertson et al. 2013).”
• Inhomogeneous recombinations during cosmic reionization (2014, background): “Although undoubtedly too simplistic, this physical picture ameliorates empirically-motivated claims for a rapid redshift evolution in galaxy properties, like the escape fraction of ionizing photons (e.g. Haardt & Madau 2012; Kuhlen & Faucher-Giguère 2012)16.”
• THE ABUNDANCE OF STAR-FORMING GALAXIES IN THE REDSHIFT RANGE 8.5–12: NEW RESULTS FROM THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN (2012, result): “…formation rate densities are consistent with previous analyses aimed at explaining the measured Thomson optical depth (e.g. Robertson et al. 2010a; Kuhlen & Faucher-Giguère 2012) and that required to produce the stellar masses of z < 8 sources observed by Spitzer (e.g., Stark et al. 2012;…”
• KECK SPECTROSCOPY OF 3 < z < 7 FAINT LYMAN BREAK GALAXIES: THE IMPORTANCE OF NEBULAR EMISSION IN UNDERSTANDING THE SPECIFIC STAR FORMATION RATE AND STELLAR MASS DENSITY (2012, result): “Given the consistency with the SFRD (Figure 8), these results are not surprisingly similar to inferences obtained from the UV LF (e.g., Bouwens et al. 2012a; Kuhlen & Faucher-Giguère 2012).”
• Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, background): “−13 (see also Kuhlen & Faucher-Giguère 2012; Finkelstein et al. 2012) to simultaneously match constraints on the reionization history and the Thomson optical depth.”
• COSMIC REIONIZATION AND EARLY STAR-FORMING GALAXIES: A JOINT ANALYSIS OF NEW CONSTRAINTS FROM PLANCK AND THE HUBBLE SPACE TELESCOPE (2015, methodology): “The number of free electrons per hydrogen nucleus is calculated following Kuhlen & Faucher-Giguère (2012) assuming doubly ionized helium at z ≤ 4.”
• Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, methodology): “The past few decades have seen tremendous advances in our ability to theoretically model the process of reionization using a variety of methods (e.g., Shapiro et al. 1994; Trac & Cen 2007; Haardt & Madau 2012; Kuhlen & Faucher-Giguère 2012; Gnedin et al. 2017).”
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions (2019, unknown): “A related issue is whether our models overrun the constraints on ionizing emissivity at lower-z plotted in the top-left panel of our Figure 7 when combined with the AGN emissivity at lower redshifts (Kuhlen & Faucher-Giguère 2012; Becker & Bolton 2013).”