A Composite<i>HST</i>Spectrum of Quasars

Zheng, Wei; Kriss, G. A.; Telfer, Randal; Grimes, John; Davidsen, A. F.

doi:10.1086/303560

Cited by 469 publications

(616 citation statements)

References 39 publications

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“…In this sense, the adopted procedure necessarily introduces an unavoidable dispersion. For example, the line ratios recently reported by Zheng et al (1996) from HST data, lead to a difference of about 25 per cent in the total luminosity with respect to Francis et al (when the lines in common to the two works are considered)…”

Section: Broad Line Luminositymentioning

confidence: 81%

See 1 more Smart Citation

Jets and accretion processes in active galactic nuclei: further clues

Celotti¹,

Padovani²,

Ghisellini³

1997

Monthly Notices of the Royal Astronomical Society

264

290

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We present evidence in favour of a link between the luminosity radiatively dissipated in the central engine of radio-loud Active Galactic Nuclei and the kinetic power in their jets. This piece of evidence is based on the relation we find between the luminosity in broad emission lines and the kinetic power in pc-scale radio jets, for a sample of radio-loud quasars for which suitable data are available in the literature. We find that the ionizing luminosity and the kinetic one are of the same order of magnitude, suggesting that the processes responsible for them are somehow related. A strong magnetic field in equipartition with the radiation field could be responsible for regulating both processes. BL Lac objects seem to follow a similar behaviour, but with comparatively fainter broad line emission.

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Section: Broad Line Luminositymentioning

confidence: 81%

“…They refer to an optical sample, mostly consisting of radio quiet sources, but no major differences in the broad line fluxes between radio quiet and radio loud objects has been clearly determined (e.g. Corbin 1992, see also Steidel & Sargent 1991, Boroson & Green 1992Zheng et al 1996).…”

Section: Broad Line Luminositymentioning

confidence: 99%

Jets and accretion processes in active galactic nuclei: further clues

Celotti¹,

Padovani²,

Ghisellini³

1997

Monthly Notices of the Royal Astronomical Society

264

290

View full text Add to dashboard Cite

show abstract

“…Zheng et al 1997;Finn et al 2014) no sizeable sample exists with X-ray spectra. Adding to this is the need for reliable BH mass estimates.…”

Section: Previous Workmentioning

confidence: 99%

Reaching the peak of the quasar spectral energy distribution – I. Observations and models

Collinson

Ward

Done

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We perform a spectral analysis of a sample of 11 medium redshift (1.5 z 2.2) quasars. Our sample all have optical spectra from the SDSS, infrared spectra from GNIRS and TSPEC, and X-ray spectra from XMM-Newton. We first analyse the Balmer broad emission line profiles which are shifted into the IR spectra to constrain black hole masses. Then we fit an energy-conserving, three component accretion model of the broadband spectral energy distribution (SED) to our multiwavelength data. Five out of the 11 quasars show evidence of an SED peak, allowing us to constrain their bolometric luminosity from these models and estimate their mass accretion rates. Based on our limited sample, we suggest that estimating bolometric luminosities from L 5100 Å and L 2−10 keV may be unreliable, as has been also noted for a low-redshift, X-ray selected AGN sample.

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“…The model is also not quite satisfactory in the optical/UV band since the observed spectra are frequently redder than predicted by the model. The model spectra, in the long wavelength limit, have the universal slope of 1/3 while the mean quasar slope above 1050Å in the Zheng et al (1997) sample is −0.99 ± 0.05.…”

Section: The Modelmentioning

confidence: 88%

Universal spectral shape of high accretion rate AGN

Nikołajuk

Różáńska

Dumont

2004

Nuclear Physics B - Proceedings Supplements

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Abstract. The spectra of quasars and NLS1 galaxies show surprising similarity in their spectral shape. They seem to scale only with the accretion rate. This is in contradiction with the simple expectations from the standard disk model which predicts lower disk temperature for higher black hole mass. Here we consider two mechanisms modifying the disk spectrum: the irradiation of the outer disk due to the scattering of the flux by the extended ionized medium (warm absorber) and the development of the warm Comptonizing disk skin under the effect of the radiation pressure instability. Those two mechanisms seem to lead to a spectrum which indeed roughly scales, as observed, only with the accretion rate. The scenario applies only to objects with relatively high luminosity to the Eddington luminosity ratio for which disk evaporation is inefficient.

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A CompositeHSTSpectrum of Quasars

Cited by 469 publications

References 39 publications

Jets and accretion processes in active galactic nuclei: further clues

Jets and accretion processes in active galactic nuclei: further clues

Reaching the peak of the quasar spectral energy distribution – I. Observations and models

Universal spectral shape of high accretion rate AGN

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