The relative growth of optical and radio quasars in SDSS

Shankar, Francesco; Sivakoff, G. R.; Vestergaard, M.; Dai, Xinyu

doi:10.1111/j.1365-2966.2009.15764.x

Cited by 22 publications

(30 citation statements)

References 127 publications

(272 reference statements)

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“…Our results (Figures 23-25) lead us to a very different conclusion than that of Shankar et al (2010; using much of the same data), who find that high-redshift RL quasars have high L L Edd , while low-redshift RL quasars have low L L Edd . We would argue instead that to reconcile the low-redshift and highredshift quasars the RL quasar masses at high-z are too low by as much 0.5 dex or more and not simply by~0.2-0.3 dex as is usually assumed.…”

Section: Mass Accretion Rate and Spincontrasting

confidence: 80%

“…Otherwise, these trends would suggest an unlikely situation whereby high-redshift and low-redshift quasars have their radio properties governed by two different process, where the switch just happens to occur at redshifts where the BH mass estimates transition from using Mg II to using C IV. Specifically, high-redshift RL quasars would have to have high L L Edd , while low-redshift RL quasars have low L L Edd (see, Shankar et al 2010). Thus, this issue is not just a matter for our analysis but speaks to the broader problem of the use of BH masses estimated from C IV emission lines.…”

Section: Bh Mass and Accretion Ratementioning

confidence: 99%

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Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission

Kratzer

Richards

2015

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We investigate the evolution of both the radio-loud fraction (RLF) and (using stacking analysis) the mean radio loudness of quasars. We consider how these properties evolve as a function of redshift and luminosity, black hole (BH) mass and accretion rate, and parameters related to the dominance of a wind in the broad emission-line region. We match the FIRST source catalog to samples of luminous quasars (both spectroscopic and photometric), primarily from the Sloan Digital Sky Survey. After accounting for catastrophic errors in BH mass estimates at high redshift, we find that both the RLF and the mean radio luminosity increase for increasing BH mass and decreasing accretion rate. Similarly, both the RLF and mean radio loudness increase for quasars that are argued to have weaker radiation line driven wind components of the broad emission-line region. In agreement with past work, we find that the RLF increases with increasing optical/UV luminosity and decreasing redshift, while the mean radio loudness evolves in the exact opposite manner. This difference in behavior between the mean radio loudness and the RLF in -L z may indicate selection effects that bias our understanding of the evolution of the RLF; deeper surveys in the optical and radio are needed to resolve this discrepancy. Finally, we argue that radio-loud (RL) and radio-quiet (RQ) quasars may be parallel sequences, but where only RQ quasars at one extreme of the distribution are likely to become RL, possibly through slight differences in spin and/or merger history.

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Section: Mass Accretion Rate and Spincontrasting

confidence: 80%

Section: Bh Mass and Accretion Ratementioning

confidence: 99%

Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission

Kratzer

Richards

2015

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“…These parameters of FBQS 1312 + 23, viz. the BH mass and the Eddington luminosity ratio, are within the distributions found for radioloud quasars at z = 1.5 (Shankar et al 2010). However, the Eddington luminosity ratio of the source is significantly higher than the mean log λ = −0.4 (or λ ≈ 0.4) for the corresponding BH mass, or the mean log λ = −0.9 (or λ ≈ 0.125) for the corresponding redshift (Shankar et al 2010, their Figure 4).…”

Section: Bh Mass and Eddington Luminosity Ratiosupporting

confidence: 82%

XMM-NEWTONOBSERVATIONS OF THE RADIO-LOUD BROAD ABSORPTION LINE QUASAR FBQS J131213.5+231958

Mathur

Dai

2010

The Astronomical Journal

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We present XMM-Newton observations of the broad absorption line (BAL) quasar FBQS J131213.5+231958. The X-ray spectrum of the source can be well described by an absorbed power-law model in which the absorber is either ionized or only partially covers the continuum source. This can explain the apparent lack of absorption observed in the Chandra spectrum with low signal-to-noise ratio. While the power-law slope of the spectrum is similar to that of non-BAL radio-loud quasars, the Eddington luminosity ratio is likely to be significantly higher than the mean. This shows that in high-mass black holes (BHs), high Eddington accretion may not result in as steep of a spectrum as in lower-mass BHs. This provides important constraints for accretion disk models. It also provides support to the idea that BAL quasars, at least their radio-loud subclass, represent an early evolutionary stage of quasars.

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“…Further increasing the local mass density by a factor of a few, as suggested by the current estimates of the local M bh -M bulge relation, would imply a radiative efficiency proportionally lower (Novak 2013), forcing the accretion models towards somewhat extreme scenarios such as frequent radiatively inefficient accretion and/or large fractions of heavily obscured, Compton-thick active galaxies (Comastri et al 2015). In contrast, a high radiative efficiency would imply that most of the local black holes are spinning rapidly, suggesting that spin may not be the only parameter controlling radio loudness in AGN, in line with many other, independent lines of evidence (e.g., Sikora et al 2007;Shankar et al 2008Shankar et al , 2010bShankar et al , 2016.…”

Section: Direct Implications Of the Bias In The Observed Scaling Relamentioning

confidence: 81%

Selection bias in dynamically measured supermassive black hole samples: its consequences and the quest for the most fundamental relation

Shankar¹,

Bernardi²,

Sheth³

et al. 2016

Mon. Not. R. Astron. Soc.

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251

369

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We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions σ than local galaxies of similar stellar mass. We use Monte-Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the M bh -σ relation by a factor of at least ∼ 3; the bias for the M bh -M star relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that σ is more fundamental than M star or effective radius. In particular, the M bh -M star relation is mostly a consequence of the M bh -σ and σ-M star relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically-based black hole-galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed σ. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of f vir ∼ 1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.

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The relative growth of optical and radio quasars in SDSS

Cited by 22 publications

References 127 publications

Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission

Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission

XMM-NEWTONOBSERVATIONS OF THE RADIO-LOUD BROAD ABSORPTION LINE QUASAR FBQS J131213.5+231958

Selection bias in dynamically measured supermassive black hole samples: its consequences and the quest for the most fundamental relation

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