scholarly journals Behaviour of the Mg ii 2798 Å line over the full range of AGN variability

2020 ◽  
Vol 496 (1) ◽  
pp. 309-327 ◽  
Author(s):  
David Homan ◽  
Chelsea L MacLeod ◽  
Andy Lawrence ◽  
Nicholas P Ross ◽  
Alastair Bruce
Keyword(s):  
Active Galactic Nuclei ◽  
Full Range ◽  
Population Sample ◽  
Galactic Nuclei ◽  
Baldwin Effect ◽  
Broad Emission ◽  
Line Region ◽  
Extreme Variability ◽  
First Time ◽  
The Continuum

ABSTRACT We investigate the responsiveness of the 2798 Å Mg ii broad emission line in active galactic nuclei (AGNs) on time-scales of several years. Our study is based on a sample of extremely variable AGNs as well as a broad population sample. The observed response of the line in previous studies has been mixed. By focusing on extreme variability (|Δg| > 1), we find that Mg ii clearly does respond to the continuum. However, the degree of responsiveness varies strikingly from one object to another: We see cases of Mg ii changing by as much as the continuum, more than the continuum, or very little at all. In 74 per cent of the highly variable sample, the behaviour of Mg ii corresponds with that of H β, with 30 per cent of the objects showing large variations in both lines. We do not detect any change in the line width that would correspond to broad-line region ‘breathing’, in accordance with results from the literature. Some of the objects in our highly variable sample show a clear asymmetry in the Mg ii profile. This skewness can be both to the blue and the red of the line centre. Results from our broad population sample show that highly variable quasars have lower Eddington ratios. This result holds for the variability of the continuum, but the correlation is significantly reduced for the variability of the Mg ii line. For the first time, we present an overview of the value of the intrinsic Baldwin effect for Mg ii in a large sample.

scholarly journals Spectral Variability in Seyfert Galaxies

1987 ◽  
Vol 121 ◽  
pp. 161-167
Author(s):  
B.M. Peterson
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
Spectral Variability ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region ◽  
Order Of Magnitude ◽  
Optical Continuum

Recent observations of spectral variability in active galactic nuclei have established the connection between the broad emission-line and optical continuum flux changes. The inferred size of the broad-line region is at least an order of magnitude smaller than conventional estimates based on photoionization models, which leads to new conclusions about the nature of the broad-line region.

scholarly journals Velocity Diagnostics of the Broad Emission-Line Region of Active Galactic Nuclei

1997 ◽  
Vol 159 ◽  
pp. 175-178 ◽  
Author(s):  
Brian Espey
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Nuclear Region ◽  
Driving Mechanisms ◽  
Broad Emission ◽  
Line Region ◽  
Broad Emission Line ◽  
Ongoing Project

AbstractWe present a brief review of emission-line velocity differences, and describe an ongoing project to determine the driving mechanisms responsible. We conclude with a brief outline of the use of velocity differences as probes of the conditions in the nuclear region of AGNs.

scholarly journals The polarized signal from broad emission lines in AGNs

2019 ◽  
Vol 491 (1) ◽  
pp. 1-12 ◽  
Author(s):  
P Lira ◽  
R W Goosmann ◽  
M Kishimoto ◽  
R Cartier
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Position Angle ◽  
Emission Lines ◽  
Type I ◽  
Line Profiles ◽  
Scattering Media ◽  
Broad Emission ◽  
Line Region ◽  
Scattering Signal

ABSTRACT Using the stokes Monte Carlo radiative transfer code, we revisit the predictions of the spectropolarimetric signal from a disc-like broad emission line region (BLR) in type I active galactic nuclei due to equatorial scattering. We reproduce the findings of previous works, but only for a scatterer that is much more optically and geometrically thick than previously proposed. We also find that when taking into account the polarized emission from all regions of the scatterer, the swing of the polarization position angle (PA) is in the opposite direction to that originally proposed. Furthermore, we find that the presence of outflows in the scattering media can significantly change the observed line profiles, with the PA of the scattering signal being enhanced in the presence of radially outflowing winds. Finally, a characteristically different PA profile, shaped like an ‘M’, is seen when the scatterer is co-spatial with the BLR and radially outflowing.

scholarly journals Results from Five Years of Spectrophotometric Monitoring of 28 Palomar-Green Quasars

1997 ◽  
Vol 159 ◽  
pp. 159-162
Author(s):  
Shai Kaspi
Keyword(s):  
Active Galactic Nuclei ◽  
Time Lag ◽  
Monitoring Program ◽  
Galactic Nuclei ◽  
Light Curves ◽  
Reliable Measurement ◽  
Line Region ◽  
Order Of Magnitude ◽  
Sampling Intervals ◽  
The Continuum

AbstractWe present 5 years of results from a spectrophotometric monitoring program of 28 quasars. The typical sampling intervals are several months. We show the light curves obtained for two quasars, PG 0804+762 and PG 0953+414. Both sources show Balmer emissionline variations which follow those of the continuum with a time lag of order 100 days. This is the first reliable measurement of such a lag in active galactic nuclei with luminosity L > 1045 erg s−1. The broad-line region (BLR) size that is implied is almost an order of magnitude larger than that measured in several Seyfert 1 galaxies and is consistent with the hypothesis that the BLR size grows as L0.5.

scholarly journals Constraints on the outer radius of the broad emission line region of active galactic nuclei

2014 ◽  
Vol 439 (1) ◽  
pp. 1051-1062 ◽  
Author(s):  
Hermine Landt ◽  
Martin J. Ward ◽  
Martin Elvis ◽  
Margarita Karovska
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Outer Radius ◽  
Broad Emission ◽  
Line Region ◽  
Broad Emission Line

scholarly journals The near-infrared broad emission line region of active galactic nuclei - II. The 1-μm continuum

2011 ◽  
Vol 414 (1) ◽  
pp. 218-240 ◽  
Author(s):  
Hermine Landt ◽  
Martin Elvis ◽  
Martin J. Ward ◽  
Misty C. Bentz ◽  
Kirk T. Korista ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Near Infrared ◽  
Galactic Nuclei ◽  
Broad Emission ◽  
Line Region ◽  
Broad Emission Line

scholarly journals Accretion in the broad line region of active galactic nuclei

2006 ◽  
Vol 2 (S238) ◽  
pp. 329-330
Author(s):  
E. Bon ◽  
L. Č. Popović ◽  
D. Ilić
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Line Profiles ◽  
Spherical Region ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region ◽  
Two Component

AbstractWe modeled the single-peaked Broad Emission Lines (BELs) with two-component model (accretion disk, with surrounding spherical region), comparing it with observational line profiles for a number of Active Galactic Nuclei (AGN). We find that the accretion in the Broad Line Region (BLR) can be present even if the profiles of BELs are single-peaked.

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