Variability of Active Galactic Nuclei

By B. Peterson. 2001

174 citations recorded by the source corpus.

Continuum and emission-line variability of active galactic nuclei provides a powerful probe of microarcsecond scale structures in the central regions of these sources. In this contribution, we review basic concepts and methodologies used in analyzing AGN variability. We develop from first principles the basics of reverberation mapping, and pay special attention to emission-line transfer functions. We discuss application of cross-correlation analysis to AGN light curves. Finally, we provide a short review of recent important results in the field.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/bcca7d0a0c9784eb8c78fa3f7c696c90f48c60a4

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A 13 Year Study of Spectral Variability in NGC 5548 (2002, methodology): “Reviews of the progress of this program are also available (see, e.g., Peterson 1993, 2001; Netzer & Peterson 1997).”
Raining on black holes and massive galaxies: the top-down multiphase condensation model (2016, background): “After several decades of investigations from X-ray to radio band, it is widely accepted that most of AGN exhibits some degree of rapid variability (Ulrich, Maraschi & Urry 1997; Peterson 2001 for a few reviews), including those of BCGs (Russell et al. 2013).”
Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships (2002, methodology): “Reverberation (or echo) mapping techniques (e.g., Blandford & McKee 1982; Peterson 2001a) do not require high spatial resolution but instead utilize the intrinsic continuum source variability and light-travel time delays between the location of the ionizing continuum source and the line-emitting…”
Active galactic nuclei: what’s in a name? (2017, background): “…z = 7.1: Mortlock et al. 2011); (2) small emitting regions in most bands, of the order of a milliparsec, as inferred from their rapid variability (e.g. Ulrich et al. 1997), implying high energy densities; (3) strong evolution of their luminosity functions (LFs; e.g. Merloni and Heinz 2013); (4)…”
Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A (2018, background): “Blazar electromagnetic (EM) emission is known to be highly variable on time scales fromminutes to years (9).”
THE LICK AGN MONITORING PROJECT: BROAD-LINE REGION RADII AND BLACK HOLE MASSES FROM REVERBERATION MAPPING OF Hβ (2009, background): “However, the average time lag is simply the first moment of the so-called “transfer function,” which describes the detail d line response as a function of time and velocity (see Peterson 2001 for a full review).”
PS16dtm: A Tidal Disruption Event in a Narrow-line Seyfert 1 Galaxy (2017, background): “AGN Variability AGN have long been known to display variability in the continuum and emission lines (Peterson 2001, and references therein), generally thought to be due to changes in the accretion rate possibly related to disk instabilities or thermal fluctuations (Kawaguchi et al. 1998; Pereyra et…”
REVERBERATION MAPPING MEASUREMENTS OF BLACK HOLE MASSES IN SIX LOCAL SEYFERT GALAXIES (2010, background): “…step towards recovering velocity-dependent Hβ transfer functions, or “velocity–delay maps”, which describe the response of the emission-line to an outburst from the ionizing continuum as a function of LOS velocity and light-travel time-delay (for a tutorial, see Peterson 2001; Horne et al. 2004).”
AN ALTERNATIVE APPROACH TO MEASURING REVERBERATION LAGS IN ACTIVE GALACTIC NUCLEI (2010, methodology): “Kelly et al. (2009) demonstrated this scaling relationship between τd and LAGN by performing a linear regression of τd on LAGN, while Collier & Peterson (2001) also found a positive correlation between the characteristic timescale and black hole masses.”
The Ensemble Photometric Variability of ~25,000 Quasars in the Sloan Digital Sky Survey (2003, background): “Finally, reverberation mapping studies (Peterson 2001) show that the quasar broad line region varies in response to changes in the continuum luminosity, showing that a large fraction of variability must be intrinsic to quasars.”
Optical and radio behaviour of the BL Lacertae object 0716+714 ⋆ (2003, unknown): “Mean fluxes <F> and standard deviations σ, in mJy, are reported, together with the mean fractional variation, defined as fvar = √ σ2 − δ2/<F>, where δ2 is the mean square uncertainty of the fluxes (Peterson 2001).”
Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database (2004, methodology): “A complete tutorial on our cross-correlation methodology is provided by Peterson (2001).”