A redshift difference between high and low ionization emission-line regions in QSOs - Evidence for radial motions

Gaskell, C. M.

doi:10.1086/160481

Cited by 351 publications

(360 citation statements)

References 0 publications

Supporting

Mentioning

330

Contrasting

Order By: Relevance

“…Hu et al (2008) have claimed that there is a redshifting of the optical Fe II λ4570 emission blend relative to the NLR and Hβ. They adopt a similar explanation to that proposed by Gaskell (1982) for the blueshifting of high ionization lines -i.e., that the far side of the emission is blocked by the accretion disc and torus. To explain a redshifting, however, Hu et al (2008) propose that the region producing the optical Fe II is inflowing.…”

Section: Cases Of Apparent Outflowmentioning

confidence: 64%

“…From a comparison of the wavelengths of low-and highionization broad lines in active galactic nuclei (AGNs) Gaskell (1982) discovered that, unlike low-ionization lines, the high-ionization broad lines of AGNs have a systematic asymmetry. The centroids of the broad lines were blueshifted by about 600 km s −1 on average with respect to the low-ionization lines.…”

Section: Observational Propertiesmentioning

confidence: 99%

“…3 The disc-wind model Gaskell (1982) proposed a "disc-wind" model as a possible explanation of the blueshifting. Low-ionization lines would arise from gas associated with the accretion disc while the high-ionization lines would arise in an outflowing wind.…”

Section: Observational Propertiesmentioning

confidence: 99%

“…The outflow+obscuration (i.e., disc-wind) explanation of Gaskell (1982) has a number of strengths on theoretical and observational grounds and has therefore long been the favoured explanation. Fig.…”

Section: Strengths Of the Disc-wind Modelmentioning

confidence: 99%

“…From the profiles a key phenomenon to be explained is the systematic blueshifting of the high-ionization broad lines with respect to the systemic velocity of the host galaxy (Gaskell 1982). In this contribution we review and discuss the two main models proposed to explain the blueshifting.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The case for inflow of the broad-line region of active galactic nuclei

Gaskell

Goosmann

2016

Astrophys Space Sci

View full text Add to dashboard Cite

The high-ionization lines of the broad-line region (BLR) of thermal active galactic nuclei (AGNs) show blueshifts of a few hundred km/s to several thousand km/sec with respect to the low-ionization lines. This has long been thought to be due to the highionization lines of the BLR arising in a wind of which the far side of the outflow is blocked from our view by the accretion disc. Evidence for and against the discwind model is discussed. The biggest problem for the model is that velocity-resolved reverberation mapping repeatedly fails to show the expected kinematic signature of outflow of the BLR. The disc-wind model also cannot readily reproduce the red side of the line profiles of high-ionization lines. The rapidly falling density in an outflow makes it difficult to obtain high equivalent widths. We point out a number of major problems with associating the BLR with the outflows producing broad absorption lines. An explanation which avoids all these problems and satisfies the constraints of both the line profiles and velocity-resolved reverberation-mapping is a model in which the blueshifting is due to scattering off material spiraling inwards with an inflow velocity of half the velocity of the blueshifting. We discuss how recent reverberation mapping results are consistent with the scattering-plus-inflow model but do not support a disc-wind model. We propose that the anti-correlation of the apparent redshifting of Hβ with the blueshifting of C IV is a consequence of contamination of the red wings of Hβ by the broad wings of [O III].

show abstract

Section: Cases Of Apparent Outflowmentioning

confidence: 64%

Section: Observational Propertiesmentioning

confidence: 99%

Section: Observational Propertiesmentioning

confidence: 99%

Section: Strengths Of the Disc-wind Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations