Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

Haardt, Francesco; Madau, Piero

doi:10.1088/0004-637x/746/2/125

Cited by 1,206 publications

(1,848 citation statements)

References 106 publications

Supporting

Mentioning

1,720

Contrasting

Order By: Relevance

“…We use the results of Pawlik et al (2009) and Haardt & Madau (2012) who show that the UVB generated by reionization can act as an effective pressure term, reducing the clumping factor with z such that…”

Section: Modeling Reionizationmentioning

confidence: 99%

Reionization and Galaxy Formation in Warm Dark Matter Cosmologies

Dayal

Choudhury

Bromm

et al. 2017

ApJ

View full text Add to dashboard Cite

We compare model results from a semi-analytic (merger-tree based) framework for high-redshift (z;5-20) galaxy formation against reionization indicators, including the Planck electron scattering optical depth (τ es ) and the ionizing photon emissivity (ṅ ion ), to shed light on the reionization history and sources in Cold (CDM) and Warm Dark Matter (WDM; particle masses of m x =1.5, 3, and 5 keV) cosmologies. This model includes all ofthe key processes of star formation, supernova feedback, the merger/accretion/ejectiondriven evolution of gas and stellar mass and the effect of the ultra-violet background (UVB), created during reionization, in photo-evaporating the gas content of galaxies in halos with M h 10 9  M . We find that the delay in the start of reionization in light (1.5 keV) WDM models can be compensated by a steeper redshift evolution of the ionizing photon escape fraction and a faster mass assembly, resulting in reionization ending at comparable redshifts (z;5.5) in all the dark matter models considered. We find thatthe bulk of the reionization photons come from galaxies with a halo mass of M h 10 9  M and a UV magnitude of −15M UV −10 in CDM. The progressive suppression of low-mass halos with decreasing m x leads to a shift in the "reionization" population to larger halo masses of M h 10 9  M and −17M UV −13 for 1.5 keV WDM. We find that current observations of τ es and the ultra violet luminosity function are equally compatible with all the (cold and warm) dark matter models considered in this work. Quantifying the impact of the UVB on galaxy observables (luminosity functions, stellar mass densities, andstellar to halo mass ratios) for different DM models, we propose that global indicators including the redshift evolution of the stellar mass density and the stellar mass-halo mass relation, observable with the James Webb Space Telescope, can be used to distinguish between CDM and WDM (1.5 keV) cosmologies.

show abstract

Section: Modeling Reionizationmentioning

confidence: 99%

Reionization and Galaxy Formation in Warm Dark Matter Cosmologies

Dayal

Choudhury

Bromm

et al. 2017

ApJ

View full text Add to dashboard Cite

show abstract

“…we adopt the UV background from Haardt & Madau (2012). We discuss the influence of our choice of ionizing background on our results in Sec.…”

Section: Enzo Simulationmentioning

confidence: 99%

“…In addition to correcting this error, our current simulations are an improvement over that previous work since we track non-equilibrium effects on the HI fraction directly, while Y12 assumed ionization equilibrium and calculated the HI fraction via post processing with CLOUDY (Ferland et al, 1998(Ferland et al, , 2013. In addition, we implement the most up to date ionizing background from Haardt & Madau (2012), which was not available at the time the Y12 simulations were made.…”

Section: Enzo Simulationmentioning

confidence: 99%

“…Most of these employ the Haardt & Madau (2001) ionizing background and suggest fair agreement with observation, although generally underreporting the HI column density distribution by a factor of a few. To date, only one work has examined the low redshift Lyα forest using the updated Haardt & Madau (2012) background, Kollmeier et al (2014, which strongly suggests that the updated background results in too much HI in the IGM at z = 0 at low to moderate column densities. This suggests a significant uncertainty in the sources of ionizing background radiation at low redshift, which could substantially change the neutral HI content in our simulations.…”

Section: Ionizing Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Warm gas in and around simulated galaxy clusters as probed by absorption lines

Emerick

Bryan

Putman

2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Understanding gas flows into and out of the most massive dark matter structures in our Universe, galaxy clusters, is fundamental to understanding their evolution. Gas in clusters is well studied in the hot (> 10 6 K) and cold (< 10 4 K) regimes, but the warm gas component (10 4 -10 6 K) is poorly constrained. It is challenging to observe directly, but can be probed through Lyα absorption studies. We produce the first systematic study of the warm gas content of galaxy clusters through synthetic Lyα absorption studies using cosmological simulations of two galaxy clusters produced with Enzo. We explore the spatial and kinematic properties of our cluster absorbers, and show that the majority of the identified absorbers are due to fast moving gas associated with cluster infall from IGM filaments. Towards the center of the clusters, however, the warm IGM filaments are no longer dominant and the absorbers tend to have higher column densities and metallicities, representing stripped galaxy material. We predict that the absorber velocity distribution should generally be bi-modal and discuss the effects of cluster size, mass, and morphology on the properties of the identified absorbers, and the overall cluster warm gas content. We find tentative evidence for a change in the well known increasing N HI with decreasing impact parameter for the most massive dark matter halos. Our results are compared directly to observations of Lyα absorbers in the Virgo cluster, and provide predictions for future Lyα absorption studies.

show abstract

“…According to our current understanding of the reionisation history of the Universe (Fan et al 2006;McQuinn et al 2009;Jarosik et al 2011;Haardt & Madau 2012), hydrogen was reionised by the ultraviolet radiation of the first stars and quasars, starting at z 10; with the increasing overlap of IGM H ii regions, hydrogen reionisation was completed around z 6 , leaving the IGM completely transparent to photons with hν > 13.6 eV. During the early stages of H i reionisation, the ionising radiation field was sufficiently hard to ionise He i (IP = 24.6 eV), but not He ii (IP = 54.4 eV).…”

Section: Introductionmentioning

confidence: 99%

The ESO UVES Advanced Data Products Quasar Sample – IV. On the deficiency of argon in DLA systems

Zafar¹,

Vladilo²,

Péroux³

et al. 2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

In this work, we study argon abundances in the interstellar medium of high-redshift galaxies (2.0 z abs 4.2) detected as Damped Lyα absorbers (DLA) in the spectra of background quasars. We use high-resolution quasar spectra obtained from the ESO-UVES advanced data products (EUADP) database. We present 3 new measurements and 5 upper limits of Ar i. We further compiled DLAs/sub-DLA data from the literature with measurements available of argon and α-capture elements (S or Si), making up a total of 37 systems, i.e. the largest DLA argon sample investigated so far. We confirm that argon is generally deficient in DLAs, with a mean value [Ar/α] ≃ −0.4 ± 0.06 dex (standard error of the mean). The [Ar/α] ratios show a weak, positive trend with increasing H i column density and increasing absorption redshift, and a weak, negative trend with dust-free metallicity, [S/H]. Detailed analysis of the abundance ratios indicates that Ar i ionisation, rather than dust depletion or nucleosynthetic evolution, is responsible for the argon deficiency. Altogether, the observational evidence is consistent with a scenario of argon ionisation dominated by quasar metagalactic radiation modulated by local H i self-shielding inside the DLA host galaxies. Our measurements and limits of argon abundances suggest that the cosmic reionisation of He ii is completed above z ∼ 3, but more measurements at z abs > 3.5 are required to probe the final stages of this process of cosmic reionisation.

show abstract

Radiative Transfer in a Clumpy Universe. Iv. New Synthesis Models of the Cosmic Uv/X-Ray Background

Cited by 1,206 publications

References 106 publications

Reionization and Galaxy Formation in Warm Dark Matter Cosmologies

Reionization and Galaxy Formation in Warm Dark Matter Cosmologies

Warm gas in and around simulated galaxy clusters as probed by absorption lines

The ESO UVES Advanced Data Products Quasar Sample – IV. On the deficiency of argon in DLA systems

Contact Info

Product

Resources

About