scholarly journals Quantifying the impact of variable BLR diffuse continuum contributions on measured continuum interband delays

2019 ◽  
Vol 489 (4) ◽  
pp. 5284-5300 ◽  
Author(s):  
K T Korista ◽  
M R Goad
Keyword(s):  
Emission Line ◽  
Power Laws ◽  
Continuum Emission ◽  
Reverberation Mapping ◽  
Density Distributions ◽  
Line Region ◽  
Total Light ◽  
Approximate Power ◽  
Dc Component ◽  
The Impact

ABSTRACT We investigate the contribution of reprocessed continuum emission (1000–10 000 Å) originating in broad-line region (BLR) gas, the diffuse continuum (DC), to the wavelength-dependent continuum delays measured in AGN disc reverberation mapping experiments. Assuming a spherical BLR geometry, we adopt a Local Optimally emitting Cloud (LOC) model for the BLR that approximately reproduces the broad emission-line strengths of the strongest UV lines (Ly α and C iv) in NGC 5548. Within this LOC framework, we explore how assumptions about the gas hydrogen density and column density distributions influence flux and delay spectra of the DC. We find that: (i) models which match well measured emission-line luminosities and time delays also produce a significant DC component, (ii) increased $\rm {\mathit{ n}_H}$ and/or $\rm {\mathit{ N}_H}$, particularly at smaller BLR radii, result in larger DC luminosities and reduced DC delays, (iii) in a given continuum band the relative importance of the DC component to the measured interband delays is proportional (though not 1:1) to its fractional contribution to the total light in that band, (iv) the measured DC delays and DC variability amplitude depend also on the variability amplitude and characteristic variability time-scale of the driving continuum, (v) the DC radial surface emissivity distributions F(r) approximate power laws in radius with indices close to −2 (≈1:1 response to variations in the driving continuum flux), thus their physics is relatively simple and less sensitive to the unknown geometry and uncertainties in radiative transfer. Finally, we provide a simple recipe for estimating the DC contribution in disc reverberation mapping experiments.

scholarly journals The Kinematics of Quasar Broad Emission Line Regions Using a Disk-Wind Model

2017 ◽  
Vol 34 ◽  
Author(s):  
Suk Yee Yong ◽  
Rachel L. Webster ◽  
Anthea L. King ◽  
Nicholas F. Bate ◽  
Matthew J. O’Dowd ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Profile ◽  
Inclination Angle ◽  
Opening Angle ◽  
Line Profiles ◽  
Wind Model ◽  
Disk Wind ◽  
Reverberation Mapping ◽  
Broad Emission ◽  
Line Region

AbstractThe structure and kinematics of the broad line region in quasars are still unknown. One popular model is the disk-wind model that offers a geometric unification of a quasar based on the viewing angle. We construct a simple kinematical disk-wind model with a narrow outflowing wind angle. The model is combined with radiative transfer in the Sobolev, or high velocity, limit. We examine how angle of viewing affects the observed characteristics of the emission line. The line profiles were found to exhibit distinct properties depending on the orientation, wind opening angle, and region of the wind where the emission arises.At low inclination angle (close to face-on), we find that the shape of the emission line is asymmetric, narrow, and significantly blueshifted. As the inclination angle increases (close to edge-on), the line profile becomes more symmetric, broader, and less blueshifted. Additionally, lines that arise close to the base of the disk wind, near the accretion disk, tend to be broad and symmetric. Single-peaked line profiles are recovered for the intermediate and equatorial wind. The model is also able to reproduce a faster response in either the red or blue sides of the line profile, consistent with reverberation mapping studies.

scholarly journals Time-Resolved Spectroscopy of Accretion Disks in Algols

1989 ◽  
Vol 107 ◽  
pp. 51-61 ◽  
Author(s):  
Ronald H. Kaitchuck
Keyword(s):  
Emission Line ◽  
Accretion Disks ◽  
Velocity Fields ◽  
Continuum Emission ◽  
Turbulent Structures ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Long Period ◽  
Short Period ◽  
The Impact

AbstractTime-resolved spectroscopy during the eclipse of short-period Algol systems, has shown their accretion disks to be small, turbulent structures with non-Keplerian velocity fields and asymmetries between the leading and trailing sides of the disk. These transient disks are produced by the impact of the gas stream on the mass-gaining star, and occur in systems where the star is just large enough to ensure the stream collision is complete. These emission line disks and the excess continuum emission do not always occur together. The permanent accretion disks in at least a few of the long-period Algol systems have features in common with the transient disks including non-Keplerian velocity fields.

scholarly journals Reverberation Mapping Analysis of the Broad-Line Region in Seyfert Galaxy NGC 4151

1998 ◽  
Vol 188 ◽  
pp. 424-425
Author(s):  
S.J. Xue ◽  
F.Z. Cheng
Keyword(s):  
Emission Line ◽  
Time Lag ◽  
Seyfert Galaxy ◽  
Broad Line ◽  
Reverberation Mapping ◽  
Ngc 4151 ◽  
Broad Line Region ◽  
Spectroscopic Monitoring ◽  
Line Region ◽  
The Continuum

One of the primary goals of AGN variability studies has been to determine the size of broad-line region (BLR) through the reverberation mapping technique. In a recent international multiwavelength spectroscopic monitoring campaign, NGC 4151 has been observed intensively by ground-based telescopes for a period of over 2 months, with a typical temporal resolution of 1 day. The main result from this optical campaign is that finding the variation in the emission line flux (Hβ or Hα) lagging the continuum by 0-3 days (1993 campaign: Kaspi et al. 1996). This is in contrast to the past results in which a time lag of 9±2 days was found for the same emission line (1988 campaign: Maoz et al. 1991). Such a BLR “size problem” may be caused by a different variability timescale of the ionizing continuum or a real change in BLR gas distribution in the 5.5 yr interval between the two watch campaigns. In order to clarify which of the two possibilities is most likely the real case, we performed further reverberation analysis on both optical datasets.

scholarly journals The Interaction of Quasar Winds and the Circumquasar Environment

1983 ◽  
Vol 6 ◽  
pp. 593-601
Author(s):  
J. E. Dyson
Keyword(s):  
Emission Line ◽  
High Speed ◽  
Stellar Winds ◽  
Lower Velocity ◽  
Interstellar Clouds ◽  
Line Region ◽  
Cool Gas ◽  
Set Up ◽  
The Impact ◽  
Narrow Emission

High speed winds from quasars interact with the gas and stars in a surrounding galaxy and produce a variety of effects. The winds sweep up the general interstellar matter into fast moving shells of cool gas which can produce lower velocity (≲, 0.01c) sharp absorption line systems. The impact of the wind on dense interstellar clouds may contribute to the narrow emission line region. Finally, supernovae or stellar winds near the QSO set up shock waves in the outflow. Shocked QSO wind material is responsible for the broad emission line material.

Recent results of measuring black hole masses via reverberation mapping

2019 ◽  
Vol 15 (S356) ◽  
pp. 116-121
Author(s):  
Shai Kaspi
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Continuum Emission ◽  
Mapping Technique ◽  
Reverberation Mapping ◽  
Line Region ◽  
Almost All ◽  
Black Hole Masses

AbstractOver the past three decades more than 100 Active Galactic Nuclei (AGNs) were measured using the reverberation mapping technique. This technique uses the response of the line emission in the Broad Line Region (BLR) to continuum emission variation and yields a measure for the distance of the BLR from the central Black Hole (BH). This in turn is used to measure the BH’s mass. Almost all of these measurements are of low-luminosity AGNs while for quasars with luminosities higher than 1046 rg s−1 there are hardly any attempts of reverberation mapping. This contribution reports on recent results from a two-decades campaigns to measure the BH mass in high-luminosity quasars using the reverberation mapping technique. BLR distance from the BH, BH mass, and AGN UV luminosity relations over eight orders of magnitude in luminosity are presented, pushing the luminosity limit to the highest point so far.

scholarly journals The broad emission-line region in AGNs and quasars: The impact of variability studies

1996 ◽  
Vol 237 (1-2) ◽  
pp. 207-240 ◽  
Author(s):  
P. M. Gondhalekar ◽  
M. R. Goad ◽  
P. T. O'Brien
Keyword(s):  
Emission Line ◽  
Broad Emission ◽  
Line Region ◽  
Broad Emission Line ◽  
The Impact

Scaling

2018 ◽  
Author(s):  
Stefan Thurner ◽  
Rudolf Hanel ◽  
Peter Klimekl
Keyword(s):  
Distribution Function ◽  
Dynamical Systems ◽  
Complex Systems ◽  
Power Law ◽  
Scaling Laws ◽  
Power Laws ◽  
Distribution Functions ◽  
Temporal Process ◽  
Approximate Power

Scaling appears practically everywhere in science; it basically quantifies how the properties or shapes of an object change with the scale of the object. Scaling laws are always associated with power laws. The scaling object can be a function, a structure, a physical law, or a distribution function that describes the statistics of a system or a temporal process. We focus on scaling laws that appear in the statistical description of stochastic complex systems, where scaling appears in the distribution functions of observable quantities of dynamical systems or processes. The distribution functions exhibit power laws, approximate power laws, or fat-tailed distributions. Understanding their origin and how power law exponents can be related to the particular nature of a system, is one of the aims of the book.We comment on fitting power laws.

scholarly journals Exploring the link between C IV outflow kinematics and sublimation-temperature dust in quasars

2020 ◽  
Author(s):  
Matthew J Temple ◽  
Manda Banerji ◽  
Paul C Hewett ◽  
Amy L Rankine ◽  
Gordon T Richards
Keyword(s):  
Emission Line ◽  
High Frequency ◽  
Infrared Emission ◽  
Black Hole Mass ◽  
Sublimation Temperature ◽  
Continuum Source ◽  
Broad Emission ◽  
Line Region ◽  
Using Data

Abstract Using data from SDSS, UKIDSS and WISE, we investigate the properties of the high-frequency cutoff to the infrared emission in ≃5000 carefully selected luminous (Lbol ∼ 1047) type 1 quasars. The strength of ≃2 μm emission, corresponding to emission from the hottest ($T>1200\rm \, K$) dust in the sublimation zone surrounding the central continuum source, is observed to correlate with the blueshift of the C iv λ1550 emission line. We therefore find that objects with stronger signatures of nuclear outflows tend to have a larger covering fraction of sublimation-temperature dust. When controlling for the observed outflow strength, the hot dust covering fraction does not vary significantly across our sample as a function of luminosity, black hole mass or Eddington fraction. The correlation between the hot dust and the C iv line blueshifts, together with the lack of correlation between the hot dust and other parameters, therefore provides evidence of a link between the properties of the broad emission line region and the infrared-emitting dusty regions in quasars.

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