An Atlas of QSO Spectra

Wilkes, Belinda; Wright, A. E.; Jauncey, D. L.; Peterson, Bruce A.

doi:10.1017/s1323358000021664

Cited by 53 publications

(45 citation statements)

References 32 publications

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“…An optical spectrum, covering a very restricted wavelength range (Wilkes et al 1983) shows only a single broad emission-line: on the assumption that this is Mg II (279 · 8 nm) a redshift of 0 · 859 is determined.…”

Section: Anomalous Objectsmentioning

confidence: 99%

The Optical/Near-IR Colours of Red Quasars

Francis

Whiting

Webster

2000

Publ. – Astron. Soc. Aust

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Abstract:We present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quasars, forming an unbiassed sub-sample of the Parkes Flat-Spectrum Sample. Data are also presented for 12 optically selected QSOs, drawn from the Large Bright QSO Survey. The spectral energy distributions of the radio-and optically-selected sources are quite different. The optically selected QSOs are all very similar: they have blue spectral energy distributions curving downwards at shorter wavelengths. Roughly 90% of the radio-selected quasars have roughly power-law spectral energy distributions, with slopes ranging from Fν ∝ ν 0 to F ν ∝ ν −2 . The remaining 10% have spectral energy distributions showing sharp peaks: these are radio galaxies and highly reddened quasars. Four radio sources were not detected down to magnitude limits of H ∼ 19 · 6. These are probably high redshift (z > 3) galaxies or quasars. We show that the colours of our red quasars lie close to the stellar locus in the optical: they will be hard to identify in surveys such as the Sloan Digital Sky Survey. If near-IR photometry is added, however, the red power-law sources can be clearly separated from the stellar locus: IR surveys such as 2MASS should be capable of finding these sources on the basis of their excess flux in the K-band.

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Section: Anomalous Objectsmentioning

confidence: 99%

The Optical/Near-IR Colours of Red Quasars

Francis

Whiting

Webster

2000

Publ. – Astron. Soc. Aust

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“…These were combined with 25 unpublished spectra drawn from the AAT archives, and 86 spectra drawn from the compilation of Wilkes et al (1983). We thus have spectra of 187 of the 323 sources in the PHFS.…”

Section: The Samplementioning

confidence: 99%

The Spectra of Red Quasars

Francis

Drake

Whiting

et al. 2001

Publ. – Astron. Soc. Aust

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We measure the spectral properties of a representative sub-sample of 187 quasars, drawn from the Parkes Half-Jansky, Flat-radio-spectrum Sample (PHFS). Quasars with a wide range of rest-frame optical/UV continuum slopes are included in the analysis: their colours range from 2 < B-K < 7. The median H-beta and [O III] emission-line equivalent widths of the red quasar sub-sample are a factor of ten weaker than those of the blue quasar sub-sample. Both the colours and the emission-line equivalent widths of the red quasars can be explained by the addition of a featureless red synchrotron continuum component to an otherwise normal blue quasar spectrum. The relative strengths of the blue and red components span two orders of magnitude at rest-frame 500nm. The blue component is weaker relative to the red component in low optical luminosity sources. This suggests that the fraction of accretion energy going into optical emission from the jet is greater in low luminosity quasars. This synchrotron model does not, however, fit around 10% of the quasars, which have both red colours and high equivalent width emission-lines. We hypothesise that these red, strong-lined quasars have intrinsically weak Big Blue Bumps. There is no discontinuity in spectral properties between the BL Lac objects in our sample and the other quasars. The synchrotron emission component only dominates the spectrum at longer wavelengths, so existing BL Lac surveys will be biassed against high redshift objects.Comment: 22 pages, 12 figures, accepted for publication in PASA. Data tables and composite spectra from the paper can be found at http://msowww.anu.edu.au/~pfrancis

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“…The light curve obtained throughout 1993 January to March is shown in Figure 3. It is obvious that the source was significantly brighter at the epoch of the detection of gamma emission than the brightness quoted by Wilkes et al (1983), which was at 18.4 mag. The source brightness decayed throughout spring 1993 to a level of 18.2 mag.…”

Section: Optical Observationsmentioning

confidence: 57%

“…The position uncertainty is nearly circular with a radius of 19Ј at 95% confidence. The gammaray source is offset by 15Ј from the position of PKS 1406Ϫ076, which has been identified by Wilkes et al (1983) as an 18.4 mag quasar at z ϭ 1.494. PKS 1406Ϫ076 has a 5 GHz flux density of 11 Jy.…”

Section: L97mentioning

confidence: 99%

High-Energy Gamma Rays from PKS 1406−076 and the Observation of Correlated Gamma-Ray and Optical Emission

Wagner¹,

Mattox

Hopp

et al. 1995

The Astrophysical Journal

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We report simultaneous observations of the optically violent variable (OVV) quasar PKS 1406Ϫ076 in the optical and gamma-ray regime. Gamma-ray emission is detected with very high significance. Both the gamma-ray and optical properties of PKS 1406Ϫ076 are typical for the group of gamma-bright active galactic nuclei detected by EGRET. During 1993 January the source was unusually bright in both frequency ranges. During this period we observed a rapid, symmetrical flare in the optical wavelength range which lasted for about 4 days. EGRET detected a similar rapid flare peaking about 22 hr after the optical outburst. Because such rapid flares are rare events, it is likely that the outbursts in the two frequency regimes are correlated. Correlated outbursts with similar profiles and a lag between the optical and gamma-ray maxima of 22 hr are inconsistent with simple versions of models suggested for the emission of high-energy radiation from blazars.

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An Atlas of QSO Spectra

Cited by 53 publications

References 32 publications

The Optical/Near-IR Colours of Red Quasars

The Optical/Near-IR Colours of Red Quasars

The Spectra of Red Quasars

High-Energy Gamma Rays from PKS 1406−076 and the Observation of Correlated Gamma-Ray and Optical Emission

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