REVIEW 5 cited by
Continuum optical-UV and X-ray variability of AGN: current results and future challenges
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
Continuum optical-UV and X-ray variability of AGN: current results and future challenges
read the original abstract
Active Galactic Nuclei (AGN) are believed to be powered by accretion of matter onto a supermassive black hole. A fundamental ingredient in shaping our understanding of AGN is their variability across the entire electromagnetic spectrum. Variability studies have the potential to help us understand the geometry of the emitting regions (in various energy bands), their causal relations, and the physics of the accretion processes. This review focuses on the observational properties of AGN variability in the optical/UV/X-ray bands (where most of the AGN luminosity is emitted) and their dependence on the AGN physical parameters (i.e. mass, luminosity, accretion rate). We also discuss possible interpretations in the context of accreting compact systems, and we review the use of variability as a tool to discover AGN and trace their properties across cosmic time, using both ground and space facilities. Finally, we discuss the opportunities and challenges provided by current and next-generation optical/X-ray surveys, to use variability as an effective tool to probe the growth of super massive black holes in the Universe.
Forward citations
Cited by 5 Pith papers
-
VAR-PZnn: A machine-learning framework for AGN photometric redshifts using color and variability-based features
VAR-PZnn combines ZTF g-band variability features with optical, MIR and NIR photometry in a mixture-density network to estimate AGN photometric redshifts with σ_NMAD=0.058 and an 8.2% outlier fraction on a 72,728-sour...
-
Simultaneous radio, optical and X-ray monitoring of hard X-ray selected AGN: a variability study
In 14 hard-X-ray-selected AGN monitored for two years, variability is strongest in X-rays and weakest in radio, and source variability explains only ~2-3% of the scatter in the Fundamental Plane.
-
X-ray disc reverberation modelling of the X-ray/UV/optical spectral/timing properties of Fairall 9
X-ray reprocessing by the accretion disc in Fairall 9 simultaneously explains the SED, UV/optical power spectra, and interband time lags only if the corona is powered externally rather than by accretion.
-
The shortest detected intra-day variability of active galactic nuclei in TESS survey
Upper limits on the shortest AGN variability timescales are log(t_min,ul/hrs) = 0.85 ± 0.55, interpreted as light-crossing times from a few to thousands of gravitational radii in regions smaller than accretion disks.
-
Physics and Astrophysics of Black Holes with eXTP
eXTP’s larger effective area and simultaneous polarimetry will tighten black-hole spin and Kerr-deviation constraints relative to NICER for the same exposure.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.