Fe<scp>ii</scp>/Mg<scp>ii</scp>Emission‐Line Ratios of QSOs within 0 &lt;<i>z</i>&lt; 5.3

Iwamuro, Fumihide; Motohara, Kentaro; Maihara, Toshinori; Kimura, Masahiko; Yoshii, Yuzuru; Doi, Mamoru

doi:10.1086/324540

Cited by 59 publications

(92 citation statements)

References 34 publications

(26 reference statements)

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“…Kelly et al (2010) and Willott et al (2010b) have shown that the intrinsic Eddington ratio distribution for a volume-limited QSO sample is indeed shifted toward lower values with respect to a luminosity-selected population. Our estimate hence represents an upper limit on the characteristic Eddington ratio of the z ∼ 6 QSO population: lower Eddington (Iwamuro et al 2002); black triangles: literature sample, z ∼ 6 (Barth et al 2003;Iwamuro et al 2004;Jiang et al 2007;Kurk et al 2007Kurk et al , 2009 ratios, according to Equation (9), would yield even longer times for the BH seeds to grow. In the future, with complete samples of QSOs at z ∼ 6, it will be possible to give better constraints on the SMBH formation models.…”

Section: Impact On Bh Formation Historymentioning

confidence: 94%

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EVIDENCE FOR NON-EVOLVING Fe II/Mg II RATIOS IN RAPIDLY ACCRETINGz∼ 6 QSOs

Rosa

Decarli

Walter

et al. 2011

ApJ

224

265

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Quasars (QSOs) at the highest known redshift (z ∼ 6) are unique probes of the early growth of supermassive black holes (BHs). Until now, only the most luminous QSOs have been studied, often one object at a time. Here we present the most extensive consistent analysis to date of 4 < z < 6.5 QSOs with observed near-infrared spectra, combining three new z ∼ 6 objects from our ongoing Very Large Telescope-Infrared Spectrometer And Array Camera program with nineteen sources from the literature. The new sources extend the existing Sloan Digital Sky Survey (SDSS) sample toward the faint end of the QSO luminosity function. Using a maximum likelihood fitting routine optimized for our spectral decomposition, we estimate the BH mass (M BH ), the Eddington ratio (defined as L bol /L Edd ), and the Fe ii/Mg ii line ratio, a proxy for the chemical abundance, to characterize both the central object and the broad-line region gas. The QSOs in our sample host BHs with masses of ∼10 9 M that are accreting close to the Eddington luminosity, consistent with earlier results. We find that the distribution of observed Eddington ratios is significantly different than that of a luminosity-matched comparison sample of SDSS QSOs at lower redshift (0.35 < z < 2.25): the average log(L bol /L Edd ) = −0.37 (L bol /L Edd ∼ 0.43) with a scatter of 0.20 dex for the z > 4 sample and the log(L bol /L Edd ) = −0.80 (L bol /L Edd ∼ 0.16) with a scatter of 0.24 dex for the 0.35 < z < 2.25 sample. This implies that, at a given luminosity, the M BH at high-z is typically lower than the average M BH of the lower-redshift population, i.e., the z > 4 sources are accreting significantly faster than the lower-redshift ones. We show that the derived Fe ii/Mg ii ratios depend sensitively on the analysis performed: our self-consistent, homogeneous analysis significantly reduces the Fe ii/Mg ii scatter found in previous studies. The measured Fe ii/Mg ii line ratios show no sign of evolution with cosmic time in the redshift range 4 < z < 6.5. If the Fe ii/Mg ii line ratio is used as a secondary proxy of the Fe/Mg abundance ratio, this implies that the QSOs in our sample have undergone a major episode of Fe enrichment in the few 100 Myr preceding the cosmic age at which they are observed.

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Section: Impact On Bh Formation Historymentioning

confidence: 94%

“…Notes. Column 1: QSO name; Columns 2 and 3: QSO right ascension and declination in J2000.0; Column 4: optical redshift from discovery paper; Column 5: NIR spectrum reference paper for the NIR spectra: A, Iwamuro et al (2002); B, Iwamuro et al (2004); C, Barth et al (2003); D, Kurk et al (2007); E, Kurk et al (2009);F, Jiang et al (2007).…”

Section: New Datamentioning

confidence: 99%

EVIDENCE FOR NON-EVOLVING Fe II/Mg II RATIOS IN RAPIDLY ACCRETINGz∼ 6 QSOs

Rosa

Decarli

Walter

et al. 2011

ApJ

224

265

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“…Of course another way to obtain a featureless continuum is to have metallicities significantly below the solar value used here. This is highly unlikely as quasars are famously known to have enhanced metallicities [53], with a near flat evolution from z = 0 up to z ∼ 4 − 5, after which it is possible that it declines to solar or even subsolar values [54].…”

Section: Individual Image-b Spectramentioning

confidence: 99%

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Reis

Reynolds

Miller

et al. 2014

Nature

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The co-evolution of a supermassive black hole with its host galaxy[1] through cosmic time is encoded in its spin[2, 3, 4]. At z > 2, supermassive black holes are thought to grow mostly by merger-driven accretion leading to high spin. However, it is unknown whether below z ∼ 1 these black holes continue to grow via coherent accretion or in a chaotic manner [5], though clear differences are predicted [3,4] in their spin evolution. An established method[6] to measure the spin of black holes is via the study of relativistic reflection features [7] from the inner accretion disk. Owing to their greater distances, there has hitherto been no significant detection of relativistic reflection features in a moderateredshift quasar. Here, we use archival data together with a new, deep observation of a gravitationally-lensed quasar at z = 0.658 to rigorously detect and study reflection in this moderate-redshift quasar. The level of relativistic distortion present in this reflection spectrum enables us to constrain the emission to originate within 3 gravitational radii from the black hole, implying a spin parameter a = 0.87 +0.08 −0.15 at the 3σ level of confidence and a > 0.66 at the 5σ level. The high spin found here is indicative of growth via coherent accretion for this black hole, and suggests that black hole growth between 0.5 z 1 occurs principally by coherent rather than chaotic accretion episodes. 1When optically-thick material, e.g. an accretion disc, is irradiated by hard X-rays, some of the flux is reprocessed into an additional 'reflected' emission component, which contains both continuum emission and atomic features. The most prominent signature of reflection from the inner accretion disc is typically the relativistic iron Kα line (6.4-6.97 keV; rest frame) [8] and the Compton reflection hump [7] often peaking at 20 − 30 keV (rest-frame). However, the deep gravitational potential and strong Doppler shifts associated with regions around black holes will also cause the forest of soft X-ray emission lines in the ∼ 0.7 − 2.0 keV range to be blended into a smooth emission feature, providing a natural explanation for the "soft-excess" observed in the X-ray spectra of nearby active galactic nuclei (AGNs) [9,10]. Indeed, both the iron line and the soft excess can be used to provide insight into the nature of the central black hole and to measure its spin [10]. Prior studies have revealed the presence of a soft-excess in 90% of quasars at[11, 12] z 1.7, and broad Fe-lines are also seen in 25% of these objects [11,13], suggesting that reflection is also prevalent in these distant AGNs. However, due to the inadequate S/N resulting from their greater distances, the X-ray spectra of these quasars were necessarily modeled using simple phenomenological parameterizations [12,14].Gravitational lensing offers a rare opportunity to study the innermost relativistic region in distant quasars [15,16], by acting as a natural telescope and magnifying the light from these sources. Quasars located between 0.5 z 1 are considerably ...

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“…Yet no evolutionary effect in the Fe ii (UV)/Mg ii ratio, up to z $ 6:4, has been found (e.g., Iwamuro et al 2002;Barth et al 2003;Diedrich et al 2002Diedrich et al , 2003. The implied abundances and their ratios show large scatter.…”

Section: Introductionmentioning

confidence: 99%

“…Many attempts have been made during last several decades to measure Fe ii (UV)/Mg ii ratios in QSOs and connect them with corresponding abundances (e.g., Kwan & Krolik 1981;Iwamuro et al 2002Iwamuro et al , 2003Iwamuro et al , 2004Freudling et al 2003). Two major techniques for subtracting or estimating the Fe ii emission spectra exist.…”

Section: Introductionmentioning

confidence: 99%

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Bruhweiler

Verner

2008

ApJ

125

173

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We use the narrow-lined broad-line region ( BLR) of the Seyfert 1 galaxy, I Zw 1, as a laboratory for modeling the ultraviolet (UV ) Fe ii 2100Y3050 8 emission complex. We calculate a grid of Fe ii emission spectra representative of BLR clouds and compare them with the observed I Zw 1 spectrum. Our predicted spectrum for log n H /(cm À3 ) ½ ¼ 11:0, log È H /(cm À2 s À1 ) ½ ¼ 20:5, and /(1 km s À1 ) ¼ 20, using Cloudy and an 830 level model atom for Fe ii with energies up to 14.06 eV, gives a better fit to the UV Fe ii emission than models with fewer levels. Our analysis indicates (1) the observed UV Fe ii emission must be corrected for an underlying Fe ii pseudocontinuum; (2) Fe ii emission peaks can be misidentified as that of other ions in active galactic nuclei (AGNs) with narrow-lined BLRs possibly affecting deduced physical parameters; (3) the shape of 4200Y4700 8 Fe ii emission in I Zw 1 and other AGNs is a relative indicator of narrow-line region ( NLR) and BLR Fe ii emission; (4) predicted ratios of Ly , C iii], and Fe ii emission relative to Mg ii k2800 agree with extinction corrected observed I Zw 1 fluxes, except for C iv k1549; (5) the sensitivity of Fe ii emission strength to microturbulence casts doubt on existing relative Fe/ Mg abundances derived from Fe ii (UV)/Mg ii flux ratios. Our calculated Fe ii emission spectra, suitable for BLRs in AGNs, are available at

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Feii/MgiiEmission‐Line Ratios of QSOs within 0 <z< 5.3

Cited by 59 publications

References 34 publications

EVIDENCE FOR NON-EVOLVING Fe II/Mg II RATIOS IN RAPIDLY ACCRETINGz∼ 6 QSOs

EVIDENCE FOR NON-EVOLVING Fe II/Mg II RATIOS IN RAPIDLY ACCRETINGz∼ 6 QSOs

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Modeling FeiiEmission and Revised Feii(UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

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