RADIATIVE TRANSFER IN A CLUMPY UNIVERSE. IV. NEW SYNTHESIS MODELS OF THE COSMIC UV/X-RAY BACKGROUND

By F. Haardt, P. Madau. 2011

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We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth modulation of the background intensity from resonant line absorption in the Lyman series of cosmic hydrogen and helium; (2) the X-ray emission from the obscured and unobscured quasars that gives origin to the X-ray background; (3) a piecewise parameterization of the distribution in redshift and column density of intergalactic absorbers that fits recent measurements of the mean free path of 1 ryd photons; (4) an accurate treatment of the photoionization structure of absorbers, which enters in the calculation of the helium continuum opacity and recombination emissivity; and (5) the UV emission from star-forming galaxies at all redshifts. We provide tables of the predicted H i and He ii photoionization and photoheating rates for use, e.g., in cosmological hydrodynamics simulations of the Lyα forest and a new metallicity-dependent calibration to the UV luminosity density-star formation rate density relation. A “minimal cosmic reionization model” is also presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with look-back time, the clumping factor of the high-redshift intergalactic medium evolves following the results of hydrodynamic simulations, and Population III stars and miniquasars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogen-ionization rates inferred from flux decrement and proximity effect measurements, predicts that cosmological H ii (He iii) regions overlap at redshift 6.7 (2.8), and yields an optical depth to Thomson scattering, τes = 0.084 that is in agreement with Wilkinson Microwave Anisotropy Probe results. Our new background intensities and spectra are sensitive to a number of poorly determined input parameters and suffer from various degeneracies. Their predictive power should be constantly tested against new observations. We are therefore making our redshift-dependent UV/X emissivities and CUBA outputs freely available for public use at http://www.ucolick.org/~pmadau/CUBA.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a84368470f25d09de1840de2851f796ec71d2feb

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Citations in the corpus

The bolometric quasar luminosity function at z = 0–7 (2020, methodology): “We fit the redshift dependence of the emissivity with a five-parameter functional form (Haardt & Madau 2012): 912 = 0 (1 + z)a exp (−bz) exp (cz) + d , (23) and we obtain the best-fit as: 912 = (1024.108 erg s−1Hz−1 cMpc−3) (1 + z)5.865 × exp (0.731z) exp (3.055z) + 15.60 .”
NEW CONSTRAINTS ON COSMIC REIONIZATION FROM THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN (2013, background): “The resulting comoving emissivity is roughly the same as atz∼ 2, corresponding to 1.5–3 photons per hydrogen atom over the age of the Universe (see also Haardt & Madau 2012).”
Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies (2016, background): “Other studies argue for a slower increase of the escape fraction with redshift (e.g. Haardt & Madau 2012).”
The stellar mass-halo mass relation of isolated field dwarfs : a critical test of ΛCDM at the edge of galaxy formation (2016, background): “There is a least a factor 2 − 4 uncertainty in the flux of ionising photons at high redshift, with galaxies being the dominant ionising source at z & 3 and quasars dominating at lower redshifts (e.g. Haardt & Madau 2012).”
Cosmic Dawn (CoDa): the first radiation-hydrodynamics simulation of reionization and galaxy formation in the Local Universe (2015, background): “…the impact of radiative feedback on galaxy formation, at low and high mass and in a number of contexts, with a fixed uniform UV background from Haardt & Madau (1996, 2012), and more recently with fully coupled RHD simulations (Pawlik et al. 2013; Wise et al. 2014; Jeon et al. 2014; Rosdahl et…”
THE COS-HALOS SURVEY: PHYSICAL CONDITIONS AND BARYONIC MASS IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM (2014, background): “…effects of implementing different slopes and intensities of the background radiation field, including a comparison between Haardt & Madau (2001) and Haardt & Madau (2012), and find the derived ionization parameters and metallicities remain consistent within a few tenths of a dex for a range of…”
MUFASA: Galaxy Formation Simulations With Meshless Hydrodynamics (2016, methodology): “We do not employ the more recent Haardt & Madau (2012) determination owing to concerns regarding its low H i ionisation rate at z = 0 which has spurred the so-called photon underproduction crisis (Kollmeier et al. 2014).”
The difficulty of getting high escape fractions of ionizing photons from high-redshift galaxies: A view from the FIRE cosmological simulations (2015, background): “Star-forming galaxies at high redshifts are thought to be the dominant source of hydrogen reionization (e.g. Madau et al. 1999; Faucher-Giguère et al. 2008; Haardt & Madau 2012).”
Large Ly α opacity fluctuations and low CMB τ in models of late reionization with large islands of neutral hydrogen extending to z < 5.5 (2018, result): “Reionization is considerably late in our simulation compared to most models in the literature (e.g., Haardt & Madau 2012), and is comparable to the ‘Very Late’ model shown by Choudhury et al. (2015) to be consistent with the rapid disappearence of Lyα emission of high-redshift galaxies.”
Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, methodology): “There is a wealth of reionization models, which either use an analytical framework driven by observations of high-z galaxies (Madau et al. 1999; Haardt & Madau 2012; Robertson et al. 2013, 2015; Duncan & Conselice 2015), are semianalytical (e.g Benson et al. 2006; Wyithe & Cen 2007; Dayal et al.…”
Inferring the astrophysics of reionization and cosmic dawn from galaxy luminosity functions and the 21-cm signal (2018, methodology): “Indeed similar approaches combining LFs and EoR measurements have been used by several studies to constrain the escape fraction and its redshift evolution (e.g. Haardt & Madau 2012; Kuhlen & FaucherGiguère 2012; Mitra et al. 2013; Robertson et al. 2013; Price et al. 2016).”
The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time (2014, methodology): “In turn, these results inform model predictions for evolution in the extragalactic UV background (Faucher-Giguère et al. 2009; Haardt & Madau 2012; Becker & Bolton 2013).”
Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe (2015, methodology): “In the same figure 5 the AGN model prediction by Haardt & Madau (2012) is also shown for comparison.”
On the evolution of the H i column density distribution in cosmological simulations (2012, methodology): “…ionization rates and the small-scale structure of the absorbers, has been found to have no significant impact on the simulated HI CDDF (Pontzen et al. 2008; McQuinn & Switzer 2010; Altay et al. 2011). c© 0000 RAS, MNRAS 000, 000–000 on Haardt & Madau (2001) together with Haardt & Madau (2012).”
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.”
Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries (2016, background): “…galaxies, there is still no consensus on the relative contributions of these sources as a function of epoch (e.g., Haardt & Madau 1996; Volonteri & Gnedin 2009; Robertson et al. 2010; Haardt & Madau 2012; Kollmeier et al. 2014; Bouwens et al. 2015; Madau & Haardt 2015, and references therein).”
CANDELS: THE CONTRIBUTION OF THE OBSERVED GALAXY POPULATION TO COSMIC REIONIZATION (2012, background): “The radiative transfer simulations of Haardt & Madau (2012) also find a relatively high escape fraction, and one which rises with redshift.”