The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

M.C. Bentz; K.D. Denney; Marianne Vestergaard; C.J. Grier; B.M. Peterson; G. De Rosa; R.W. Pogge; A.J. Barth; V.N. Bennert; G. Canalizo; A.V. Filippenko; W. Li; E.L. Gates; J.E. Greene; M.A. Malkan; D. Stern; T. Treu; J.-H. Woo

doi:10.1088/0004-637X/767/2/149

The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

M.C. Bentz, K.D. Denney, Marianne Vestergaard, C.J. Grier, B.M. Peterson, G. De Rosa, R.W. Pogge, A.J. Barth, V.N. Bennert, G. Canalizo, A.V. Filippenko, W. Li, E.L. Gates, J.E. Greene, M.A. Malkan, D. Stern, T. Treu, J.-H. Woo

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412 Citations (Scopus)

Abstract

We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R_BLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

Original language	English
Article number	149
Journal	Astrophysical Journal
Volume	767
Issue number	2
ISSN	0004-637X
DOIs	https://doi.org/10.1088/0004-637X/767/2/149
Publication status	Published - 20 Apr 2013

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Bentz, M. C., Denney, K. D., Vestergaard, M., Grier, C. J., Peterson, B. M., De Rosa, G., Pogge, R. W., Barth, A. J., Bennert, V. N., Canalizo, G., Filippenko, A. V., Li, W., Gates, E. L., Greene, J. E., Malkan, M. A., Stern, D., Treu, T., & Woo, J-H. (2013). The low-luminosity end of the radius-luminosity relationship for active galactic nuclei. Astrophysical Journal, 767(2), [149]. https://doi.org/10.1088/0004-637X/767/2/149

Bentz, MC, Denney, KD, Vestergaard, M, Grier, CJ, Peterson, BM, De Rosa, G, Pogge, RW, Barth, AJ, Bennert, VN, Canalizo, G, Filippenko, AV, Li, W, Gates, EL, Greene, JE, Malkan, MA, Stern, D, Treu, T & Woo, J-H 2013, 'The low-luminosity end of the radius-luminosity relationship for active galactic nuclei', Astrophysical Journal, vol. 767, no. 2, 149. https://doi.org/10.1088/0004-637X/767/2/149

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abstract = "We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create {"}AGN-free{"} images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the RBLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.",

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AU - Bentz, M.C.

AU - Denney, K.D.

AU - Vestergaard, Marianne

AU - Grier, C.J.

AU - Peterson, B.M.

AU - De Rosa, G.

AU - Pogge, R.W.

AU - Barth, A.J.

AU - Bennert, V.N.

AU - Canalizo, G.

AU - Filippenko, A.V.

AU - Li, W.

AU - Gates, E.L.

AU - Greene, J.E.

AU - Malkan, M.A.

AU - Stern, D.

AU - Treu, T.

AU - Woo, J.-H.

PY - 2013/4/20

Y1 - 2013/4/20

N2 - We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the RBLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

AB - We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the RBLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

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VL - 767

JO - Astrophysical Journal

JF - Astrophysical Journal

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ER -

The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

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