The near-infrared radius-luminosity relationship for active galactic nuclei

Abstract

Black hole masses for samples of active galactic nuclei (AGN) are currently estimated from single-epoch optical spectra. In particular, the size of the broad-line emitting region needed to compute the black hole mass is derived from the optical or ultraviolet continuum luminosity. Here we consider the relationship between the broad-line region size, R, and the near-infrared (near-IR) AGN continuum luminosity, L, as the near-IR continuum suffers less dust extinction than at shorter wavelengths and the prospects for separating the AGN continuum from host-galaxy starlight are better in the near-IR than in the optical. For a relationship of the form R propto L^alpha, we obtain for a sample of 14 reverberation-mapped AGN a best-fit slope of alpha=0.5+/-0.1, which is consistent with the slope of the relationship in the optical band and with the value of 0.5 naively expected from photoionisation theory. Black hole masses can then be estimated from the near-IR virial product, which is calculated using the strong and unblended Paschen broad emission lines (Pa alpha or Pa beta).

5 pages, 2 figures, accepted by MNRAS Letters

References in corpus (6)

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• A near-infrared relationship for estimating black hole masses in active galactic nuclei
• On the black hole mass of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342
• The relativistic jet of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342
• The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548
• A novel black-hole mass scaling relation based on coronal gas, and its dependence with the accretion disc
• Constraints on the outer radius of the broad emission line region of active galactic nuclei
• Medium-resolution Optical and Near-Infrared Spectral Atlas of 16 2MASS-selected NIR-red Active Galactic Nuclei at $z\sim 0.3$
• The SOUX AGN Sample: SDSS-XMM-Newton Optical, Ultraviolet and X-ray selected active galactic nuclei spanning a wide range of parameter space -- Sample definition
• A complex dust morphology in the high-luminosity AGN Mrk 876
• Analyzing temporal variations of AGN emission line profiles in the context of (dusty) cloud structure formation in the broad line region
• The first spectroscopic IR reverberation programme on Mrk 509