What broad emission lines tell us about how active galactic nuclei work

Gaskell, C. Martin

doi:10.1016/j.newar.2009.09.006

Cited by 209 publications

(205 citation statements)

References 110 publications

(128 reference statements)

Supporting

Mentioning

185

Contrasting

Unclassified

Order By: Relevance

“…First, the observational arguments for both inflow and outflow in BLR were given in a number of papers (e.g. Done & Krolik 1996;Elvis 2000;Ferland et al 2009;Gaskell 2009;Shapovalova et al 2010). Second, there has been considerable discussion of the heating efficiency of the LIL BLR: radiative heating seems too low compared with the observed radiation field, and additional mechanical heating seems to be required (Collin-Souffrin et al 1988;Bottorff & Ferland 2002;Shapovalova et al 2004;Shapovalova et al 2010).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The origin of the broad line region in active galactic nuclei

Czerny

Hryniewicz

2010

A&A

244

213

View full text Add to dashboard Cite

Aims. Although broad emission lines are the most reliable signature of the nuclear activity of a galaxy and the location of the emitting material is well measured by the reverberation method, the physical cause of the formation of the broad line region remains unclear. We attempt to place some constraints on its origin. Methods. We study the properties of the accretion disk underlying the broad line region. Results. We find that the effective temperature at the disk radius corresponding to the location of the broad line region, as inferred from the Hβ line, is universal in all monitored sources and equal to 1000 K. This value is close to the limiting value that permits the existence of the dust. Conclusions. The likely origin of the low ionization part of the broad line region is the strong local dusty wind from the disk. This wind becomes exposed to the irradiation by the central regions when moving higher above the disk surface and subsequently behaves like a failed wind, thus leading to a local mixture of inflow and outflow. This may provide the physical explanation of the turbulence needed both to smooth the line profiles as well as provide additional mechanical heating.

show abstract

Section: Discussionmentioning

confidence: 99%

“…However, major uncertainties about the geometry, dynamics, and physics of BLR still exist (for a review, see e.g. Sulentic et al 2000;Gaskell 2009). …”

Section: Introductionmentioning

confidence: 99%

The origin of the broad line region in active galactic nuclei

Czerny

Hryniewicz

2010

A&A

244

213

View full text Add to dashboard Cite

show abstract

“…This implies that the BLR location is close to the equatorial plane. However, the origin and exact geometry of BLR is still relatively unknown and is highly debated in the literature (see, e.g., Sulentic et al 2000;Gaskell 2009, and references therein). Elitzur et al (2014) suggest that the BLR and torus are most naturally a continuation of the accretion disc outflow.…”

Section: Origin Of the Broad-line-region Cloudsmentioning

confidence: 99%

An X-ray variable absorber within the broad line region in Fairall 51

Svoboda

Guainazzi

Longinotti

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Fairall 51 is a polar-scattered Seyfert 1 galaxy, a type of active galaxy believed to represent a bridge between unobscured type-1 and obscured type-2 objects. Fairall 51 has shown complex and variable X-ray absorption, but little is known about its origin. Aims. In our research, we observed Fairall 51 with the X-ray satellite Suzaku in order to constrain a characteristic time scale of its variability. Methods. We performed timing and spectral analysis of four observations separated by 1.5, 2, and 5.5 day intervals. Results. We found that the 0.5-50 keV broadband X-ray spectra are dominated by a primary power-law emission (with the photon index ∼2). This emission is affected by at least three absorbers with different ionisations (log ξ ≈ 1-4). The spectrum is shaped further by a reprocessed emission, possibly coming from two regions, the accretion disc and a more distant scattering region. The accretion disc emission is smeared by the relativistic effects, from which we measured the spin of the black hole as a ≈ 0.8 ± 0.2. We found that most of the spectral variability can be attributed to the least ionised absorber whose column density changed by a factor of two between the first (highest-flux) and the last (lowest-flux) observation. Conclusions. A week-long scale of the variability indicates that the absorber is located at the distance ≈0.05 pc from the centre, i.e., in the broad line region.

show abstract

“…But let us recall the results obtained in the study of dynamics of the line-driven diskwind, where the kinematics of the gas show that both infall and outflow can occur in different regions of the wind at the same time (see Proga et al 1998Proga et al , 2000, which depends on radiation force. Also, recently Gaskell (2009) reported the possibility that an inflow is present in the BLR of AGN.…”

Section: Variability and The Blr Structure Of 3c 3903mentioning

confidence: 99%

“…The physics and geometry of the BLR are uncertain, and an investigation of the BEL shape variability in a long period is very useful for determining the BLR nature. The profiles of the BELs in AGN can indicate the geometry of emitting plasma in the BLR (see Sulentic et al 2000;Popović et al 2004;Gaskell 2009;Zamfir et al 2010, etc. ).…”

Section: Introductionmentioning

confidence: 99%

Spectral optical monitoring of 3C 390.3 in 1995–2007

Popovic

Shapovalova

Ilić

et al. 2011

A&A

View full text Add to dashboard Cite

Context. We present a study of the variability of the broad emission-line parameters of 3C390.3, an active galaxy with the doublepeaked emission-line profiles. We give a detailed analysis of the variation in the broad Hα and Hβ emission-line profiles, the ratios, and the Balmer decrement of different line segments. Aims. We explore the disk structure with an investigation of the variability of the broad-line profiles. This is assumed to emit the broad double-peaked Hβ and Hα emission lines in the spectrum of 3C390.3. Methods. We divided the observed spectra into two periods (before and after the outburst in 2002) and separately analyzed the variation in these two periods. First we analyzed the spectral emission-line profiles of the Hα and Hβ lines and measured the peak positions. Then, we divided the lines into several segments and measured the line-segment fluxes. The Balmer decrement variation for the entire Hα and Hβ fluxes and for the line segments was investigated and discussed. Additionally, we modeled the variations in the line parameters with an accretion disk model and compared our modeled line parameter variations with observed ones. Results. We compared the variability in the observed line parameters with the disk model predictions and found that the variation in line profiles and in the line segments corresponds to the emission of a disk-like broad-line region (BLR). But there is probably another additional emission component that contributes to the Hα and Hβ line center. We found that the variation in the line profiles is caused by the variation in the parameters of the disk-like BLR, first of all in the inner (outer) radius, which can well explain the line parameters variations in Period I. The Balmer decrement across the line profile has a bell-like shape and is affected not only by physical processes in the disk, but also by different emitting disk dimension of the Hα and Hβ line. Conclusions. The geometry of the BLR of 3C390.3 seems to be very complex, and inflows/outflows may be present, but evidently the broad-line region with its disk-like geometry is the dominant emitter.

show abstract

What broad emission lines tell us about how active galactic nuclei work

Cited by 209 publications

References 110 publications

The origin of the broad line region in active galactic nuclei

The origin of the broad line region in active galactic nuclei

An X-ray variable absorber within the broad line region in Fairall 51

Spectral optical monitoring of 3C 390.3 in 1995–2007

Contact Info

Product

Resources

About