The Spectra of Red Quasars

Francis, Paul; Drake, Catherine L.; Whiting, M. T.; Drinkwater, Michael J.; Webster, R. L.

doi:10.1071/as01039

Cited by 20 publications

(14 citation statements)

References 19 publications

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“…The total sample comprises 323 radio sources. A sub‐sample of 39 of these sources was compiled by OWW02 for which it was possible to obtain spectra covering the broad Hβ emission line from various sources in the literature (Wilkes et al 1983; Francis et al 2001).…”

Section: The Flat‐spectrum Samplementioning

confidence: 99%

On the black hole mass–radio luminosity relation for flat-spectrum radio-loud quasars

Jarvis

McLure

2002

Monthly Notices of the Royal Astronomical Society

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A new analysis of the connection between black hole mass and radio luminosity in radio‐selected flat‐spectrum quasars (FSQs) is presented. In contrast to recent claims in the literature, we find no evidence that the black hole masses of radio‐selected FSQs are systematically lower than those of luminous optically selected radio‐loud quasars. The black hole masses of the FSQs are estimated via the virial black hole mass estimator which utilizes the linewidth of the Hβ emission line as a tracer of the central gravitational potential. By correcting for the inevitable effects of inclination, incurred as a result of the FSQs being viewed close to the line of sight, we find that the black hole masses of the FSQs with intrinsically powerful radio jets are confined, virtually exclusively, to Mbh > 108 M⊙. This is in good agreement with previous studies of optically selected FSQs and steep‐spectrum radio‐loud quasars. Finally, following the application of a realistic Doppler boosting correction, we find that the FSQs occupy a wide range in intrinsic radio luminosity, and that many sources would be more accurately classified as radio‐intermediate or radio‐quiet quasars. This range in radio luminosity suggests that the FSQs are fully consistent with an upper boundary on radio power of the form L5 GHz∝Mbh2.5.

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Section: The Flat‐spectrum Samplementioning

confidence: 99%

On the black hole mass–radio luminosity relation for flat-spectrum radio-loud quasars

Jarvis

McLure

2002

Monthly Notices of the Royal Astronomical Society

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“…Many radio-selected quasars are quite red, although this redness may be caused by synchrotron emission or weak blue bump emission, rather than dust (Webster et al 1995;Baker & Hunstead 1995;Francis, Whiting, & Webster 2000;Francis et al 2001). At least a few radio-selected quasars, however, show unmistakable evidence of severe dust reddening (Malhotra, Rhoads, & Turner 1997;Courbin et al 1998; Gregg et al 2002).…”

Section: Luminous Qsosmentioning

confidence: 99%

An Unbiased Census of Active Galactic Nuclei in the Two Micron All Sky Survey

2004

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We present an unbiased near-IR-selected AGN sample, covering 12.56 deg 2 down to K s $ 15:5, selected from the Two Micron All Sky Survey (2MASS). Our only selection effect is a moderate color cut (J ÀK s > 1:2) designed to reduce contamination from Galactic stars. We observed both pointlike and extended sources. Using the brute-force capabilities of the Two Degree Field multifiber spectrograph on the Anglo-Australian Telescope, we obtained spectra of 65% of the target list: an unbiased subsample of 1526 sources. Eighty percent of the 2MASS sources in our fields are galaxies, with a median redshift of 0.15. The remainder are K and M dwarf stars. We find tentative evidence that Seyfert 2 nuclei are more common in our IR-selected survey than in blue-selected galaxy surveys. We estimate that 5:1 AE 0:7% of the galaxies have Seyfert 2 nuclei with H equivalent widths greater than 0.4 nm, measured over a spectroscopic aperture of radius $2.5 kpc. Blue-selected galaxy samples only find Seyfert 2 nuclei meeting these criteria in $1.5% of galaxies. We find that 1:2 AE 0:3% of our sources are broadline (type 1) AGNs, giving a surface density of 1:0 AE 0:3 deg 2 , down to K s < 15:0. This is the same surface density of type 1 AGNs as optical samples down to B < 18:5. Our type 1 AGNs, however, mostly lie at low redshifts, and host galaxy light contamination would make $50% of them hard to find in optical QSO samples. We conclude that the type 1 AGN population found in the near-IR is not dramatically different from that found in optical samples. There is no evidence for a large population of AGNs that could not be found at optical wavelengths, although we can only place very weak constraints on any population of dusty high-redshift QSOs. In contrast, the incidence of type 2 (narrow-line) AGNs in a near-IR-selected galaxy sample seems to be higher than in a blue-selected galaxy sample.

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“…This paper suggests that traditional samples of red quasars that impose cuts on observed colors or spectral index (e.g., Webster et al 1995;Francis et al 2001;Wilkes et al 2002;Gregg et al 2002) are too heterogeneous with redshift to yield physically homogeneous samples of red quasars. Spectral indexes are sensitive to the choice of continuum windows, and simple color cuts necessarily ignore the significant contribution that emission and absorption lines make to the colors of quasars as a function of redshift.…”

Section: Introductionmentioning

confidence: 99%

Red and Reddened Quasars in the Sloan Digital Sky Survey

Richards¹,

Hall²,

Berk³

et al. 2003

378

303

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We investigate the overall continuum and emission-line properties of quasars as a function of their optical/ UV spectral energy distributions. Our sample consists of 4576 quasars from the Sloan Digital Sky Survey (SDSS) that were chosen using homogeneous selection criteria. Expanding on our previous work, which demonstrated that the optical/UV color distribution of quasars is roughly Gaussian but with a red tail, here we distinguish between (1) quasars that have intrinsically blue (optically flat) power-law continua, (2) quasars that have intrinsically red (optically steep) power-law continua, and (3) quasars whose colors are inconsistent with a single power-law continuum. We find that 273 (6.0%) of the quasars in our sample fall into the latter category and appear to be redder because of SMC-like dust extinction and reddening rather than because of synchrotron emission. Even though the SDSS quasar survey is optically selected and flux-limited, we demonstrate that it is sensitive to dust reddened quasars with E(BÀV ) d 0.5, assuming a classical SMC extinction curve. The color distribution of our SDSS quasar sample suggests that the population of moderately dust reddened, but otherwise normal (i.e., type 1) quasars is smaller than the population of unobscured quasars: we estimate that a further 10% of the quasar population with M i < À25.61 is missing from the SDSS sample because of extinction, bringing the total fraction of dust-reddened quasars to 15% of broad-line quasars. We also investigate the emission-and absorption-line properties of these quasars as a function of color and comment on how some of these results relate to Boroson-Green-type eigenvectors. Quasars with intrinsically red (optically steep) powerlaw continua tend to have narrower Balmer lines and weaker C iv, C iii], He ii, and 3000 Å bump emission as compared with bluer (optically flatter) quasars. The change in strength of the 3000 Å bump appears to be dominated by the Balmer continuum and not by Fe ii emission. The dust-reddened quasars have even narrower Balmer lines and weaker 3000 Å bumps, in addition to having considerably larger equivalent widths of [O ii] and [O iii] emission. The fraction of broad absorption line quasars (BALQSOs) increases from $3.4% for the bluest quasars to perhaps as large as 20% for the dust-reddened quasars, but the intrinsic color distribution will be much bluer if all BALQSOs are affected by dust reddening.

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The Spectra of Red Quasars

Cited by 20 publications

References 19 publications

On the black hole mass–radio luminosity relation for flat-spectrum radio-loud quasars

On the black hole mass–radio luminosity relation for flat-spectrum radio-loud quasars

An Unbiased Census of Active Galactic Nuclei in the Two Micron All Sky Survey

Red and Reddened Quasars in the Sloan Digital Sky Survey

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