AGN Reverberation Mapping

Abstract

Reverberation mapping is now a well-established technique for investigating spatially-unresolved structures in the nuclei of distant galaxies with activelyaccreting supermassive black holes. Structural parameters for the broad emissionline region, with angular sizes of microarcseconds, can be constrained through the substitution of time resolution for spatial resolution. Many reverberation experiments over the last 30 years have led to a practical understanding of the requirements necessary for a successful program. With reverberation measurements now in hand for 60 active galaxies, and more on the horizon, we are able to directly constrain black hole masses, derive scaling relationships that allow large numbers of black hole mass estimates throughout the observable Universe, and begin investigating the detailed geometry and kinematics of the broad line region. Reverberation mapping is therefore one of the few techniques available that will allow a deeper understanding of the physical mechanisms involved in AGN feeding and feedback at very small scales, as well as constraints on the growth and evolution of black holes across cosmic time. In this contribution, I will briefly review the background, implementation, and major results derived from this high angular resolution technique.

Extending the Calibration of C iv-based Single-epoch Black Hole Mass Estimators for Active Galactic Nuclei*

“…These observations are associated with program GO-12922. 1 See a recent review by Bentz (2016) on the current status and future prospects for RM studies.…”

A decades-long fast-rise-exponential-decay flare in low-luminosity AGN NGC 7213

“…The time-scales, the spectral changes, and the correlations and delays between variations in the different continuum or line components will reveal the nature and location of different physical components and on their interdependencies. For example, in the reverberation mapping method, the time lag between optical/ultraviolet continuum and Hβ (Mgii, Civ also) emission lines is crucial to constrain the size of broad line regions in AGN (for a recent review, see Bentz 2016).…”

Astronomical Distance Determination in the Space Age

“…Intense emission lines, most notably Balmer lines, with kinematic width of order of thousands km/s are the most characteristic features of AGN. The variability of the emission line intensity has been noticed already by Andrillat and Souffrin (1968), and the response of the lines to the variable intrinsic continuum opened a way to reverberation mapping of the Broad Line Region (e.g., Cherepashchuk and Lyutyi, 1973;Gaskell and Sparke, 1986;Kaspi et al, 2000, ;for a review, see Peterson 2014b;Bentz 2015). In the simplest approach, the time delay between the lines and the continuum measures the size of the BLR.…”