A luminous quasar at a redshift of z = 7.085

Mortlock, D.; Warren, S. J.; Venemans, Bram; Patel, M.; Hewett, Paul C.; McMahon, R. G.; Simpson, Chris; Theuns, Tom; Gonzales-Solares, E.; Adamson, A. J.; Dye, S.; Hambly, N. C.; Hirst, Paul; Irwin, M. J.; Kuiper, E.; Lawrence, Andy; Röttgering, H. J. A.

doi:10.1038/nature10159

Cited by 1,492 publications

(1,732 citation statements)

References 29 publications

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“…10). The limits on the IGM neutrality inferred from the measurements of quasar near zones (open hexagon, Mortlock et al 2011) and the GRB damping wings (open circle, Chornock et al 2013) are also shown in the left panel of Fig. 10.…”

Section: Other Reionization Constraintsmentioning

confidence: 99%

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Sun

Furlanetto

2016

Mon. Not. R. Astron. Soc.

168

157

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Reionization is thought to have occurred in the redshift range of 6 < z < 9, which is now being probed by both deep galaxy surveys and CMB observations. Using halo abundance matching over the redshift range 5 < z < 8 and assuming smooth, continuous gas accretion, we develop a model for the star formation efficiency f of dark matter halos at z > 6 that matches the measured galaxy luminosity functions at these redshifts. We find that f peaks at ∼ 30% at halo masses M ∼ 10 11 -10 12 M , in qualitative agreement with its behavior at lower redshifts. We then investigate the cosmic star formation histories and the corresponding models of reionization for a range of extrapolations to small halo masses. We use a variety of observations to further constrain the characteristics of the galaxy populations, including the escape fraction of UV photons. Our approach provides an empirically-calibrated, physically-motivated model for the properties of star-forming galaxies sourcing the epoch of reionization. In the case where star formation in low-mass halos is maximally efficient, an average escape fraction ∼ 0.1 can reproduce the optical depth reported by Planck, whereas inefficient star formation in these halos requires either about twice as many UV photons to escape, or an escape fraction that increases towards higher redshifts. Our models also predict how future observations with JWST can improve our understanding of these galaxy populations.

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Section: Other Reionization Constraintsmentioning

confidence: 99%

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Sun

Furlanetto

2016

Mon. Not. R. Astron. Soc.

168

157

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show abstract

“…If successful, this strategy would not only represent a breakthrough in the study of the first luminous objects in the Universe, but it would also shed some light on the puzzles provided by the interpretation of the formation of SMBHs (see e.g. Fan et al 2001;Mortlock et al 2011;Petri et al 2012) and the excess recently found in the power spectrum of the cosmic Near Infrared Background fluctuations (for an overview, see Yue et al 2013). These issues will be discussed in more details in Sec.…”

Section: Introductionmentioning

confidence: 99%

Simulating the growth of intermediate-mass black holes

Pacucci

Ferrara

2015

Monthly Notices of the Royal Astronomical Society

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Theoretical models predict that a population of Intermediate Mass Black Holes (IMBHs) of mass M • ≈ 10 4−5 M might form at high (z ∼ > 10) redshift by different processes. Such objects would represent the seeds out of which z > ∼ 6 Super-Massive Black Holes (SMBHs) grow. We numerically investigate the radiation-hydrodynamic evolution governing the growth of such seeds via accretion of primordial gas within their parent dark matter halo of virial temperature T vir ∼ 10 4 K. We find that the accretion onto a Direct Collapse Black Hole (DCBH) of initial mass M 0 = 10 5 M occurs at an average rateṀ • 1.35Ṁ Edd 0.1 M yr −1 , is intermittent (duty-cycle < ∼ 50%) and lasts ≈ 142 Myr; the system emits on average at super-Eddington luminosities, progressively becoming more luminous as the density of the inner mass shells, directly feeding the central object, increases. Finally, when ≈ 90% of the gas mass has been accreted (in spite of an average super-Eddington emission) onto the black hole, whose final mass is ∼ 7 × 10 6 M , the remaining gas is ejected from the halo due to a powerful radiation burst releasing a peak luminosity L peak ∼ 3 × 10 45 erg s −1 . The IMBH is Compton-thick during most of the evolution, reaching a column density N H ∼ 10 25 cm −2 in the late stages of the simulation. We briefly discuss the observational implications of the model.

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“…In this context, quasars offer a valuable tool for exploring the [α/Fe] break at high redshift, because (i) their spectra show plenty of emission and absorption lines of metals including α elements and iron, and (ii) their brightness is great enough to provide spectra of good quality even from a far distance at z > 7 [9]. The purpose of this paper is to invent reliable diagnostics of the Mg/Fe abundance ratio for a broad-line region (BLR) cloud in a quasar.…”

Section: Introductionmentioning

confidence: 99%

Chemical Evolution of the Universe at 0.7 < z < 1.6 Derived from Abundance Diagnostics of Quasars

Sameshima¹,

Yoshii²,

Kawara³

2017

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)

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We present an analysis of Mg II λ2798 and Fe II UV emission lines for archival Sloan Digital Sky Survey (SDSS) quasars to explore diagnostics of the Mg/Fe abundance ratio in a broad-line region cloud. Our sample consists of 17,432 quasars selected from the SDSS Data Release 7 with a redshift range of 0.72 < z < 1.63. An anticorrelation between Mg II equivalent width (EW) and the Eddington ratio is found, while only a weak positive correlation is found between Fe II EW and the Eddington ratio. To investigate the origin of these differing behaviors of Mg II and Fe II emission lines, we have performed photoionization calculations using the Cloudy code. We find that their EW correlations with the Eddington ratio can be explained by just changing the cloud gas density; this indicates that the Mg II/Fe II flux ratio, which has been used as a first-order proxy for the Mg/Fe abundance ratio in chemical evolution studies with quasar emission lines, depends largely on the cloud gas density. By correcting this density dependence, we propose new diagnostics of the Mg/Fe abundance ratio for a broad-line region cloud. Using this new method, we have succeeded for the first time in measuring the evolution of the Mg/Fe abundance ratio as a function of redshift. From comparison with chemical evolution models, we suggest that α-enrichment by mass loss from metal-poor intermediate-mass stars occurred at z ∼ 2 or earlier.

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A luminous quasar at a redshift of z = 7.085

Cited by 1,492 publications

References 29 publications

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Simulating the growth of intermediate-mass black holes

Chemical Evolution of the Universe at 0.7 < z < 1.6 Derived from Abundance Diagnostics of Quasars

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