Space Telescope and Optical Reverberation Mapping Project. IX. Velocity-Delay Maps for Broad Emission Lines in NGC 5548

February 2021 • 2021ApJ...907...76H

Authors • Horne, Keith • De Rosa, G. • Peterson, B. M. • Barth, A. J. • Ely, J. • Fausnaugh, M. M. • Kriss, G. A. • Pei, L. • Bentz, M. C. • Cackett, E. M. • Edelson, R. • Eracleous, M. • Goad, M. R. • Grier, C. J. • Kaastra, J. • Kochanek, C. S. • Krongold, Y. • Mathur, S. • Netzer, H. • Proga, D. • Tejos, N. • Vestergaard, M. • Villforth, C. • Adams, S. M. • Anderson, M. D. • Arévalo, P. • Beatty, T. G. • Bennert, V. N. • Bigley, A. • Bisogni, S. • Borman, G. A. • Boroson, T. A. • Bottorff, M. C. • Brandt, W. N. • Breeveld, A. A. • Brotherton, M. • Brown, J. E. • Brown, J. S. • Canalizo, G. • Carini, M. T. • Clubb, K. I. • Comerford, J. M. • Corsini, E. M. • Crenshaw, D. M. • Croft, S. • Croxall, K. V. • Dalla Bontà, E. • Deason, A. J. • Dehghanian, M. • De Lorenzo-Cáceres, A. • Denney, K. D. • Dietrich, M. • Done, C. • Efimova, N. V. • Evans, P. A. • Ferland, G. J. • Filippenko, A. V. • Flatland, K. • Fox, O. D. • Gardner, E. • Gates, E. L. • Gehrels, N. • Geier, S. • Gelbord, J. M. • Gonzalez, L. • Gorjian, V. • Greene, J. E. • Grupe, D. • Gupta, A. • Hall, P. B. • Henderson, C. B. • Hicks, S. • Holmbeck, E. • Holoien, T. W.-S. • Hutchison, T. • Im, M. • Jensen, J. J. • Johnson, C. A. • Joner, M. D. • Jones, J. • Kaspi, S. • Kelly, P. L. • Kennea, J. A. • Kim, M. • Kim, S. • Kim, S. C. • King, A. • Klimanov, S. A. • Korista, K. T. • Lau, M. W. • Lee, J. C. • Leonard, D. C. • Li, Miao • Lira, P. • Lochhaas, C. • Ma, Zhiyuan • MacInnis, F. • Malkan, M. A. • Manne-Nicholas, E. R. • Mauerhan, J. C. • McGurk, R. • McHardy, I. M. • Montuori, C. • Morelli, L. • Mosquera, A. • Mudd, D. • Müller-Sánchez, F. • Nazarov, S. V. • Norris, R. P. • Nousek, J. A. • Nguyen, M. L. • Ochner, P. • Okhmat, D. N. • Pancoast, A. • Papadakis, I. • Parks, J. R. • Penny, M. T. • Pizzella, A. • Pogge, R. W. • Poleski, R. • Pott, J.-U. • Rafter, S. E. • Rix, H.-W. • Runnoe, J. • Saylor, D. A. • Schimoia, J. S. • Schnülle, K. • Scott, B. • Sergeev, S. G. • Shappee, B. J. • Shivvers, I. • Siegel, M. • Simonian, G. V. • Siviero, A. • Skielboe, A. • Somers, G. • Spencer, M. • Starkey, D. • Stevens, D. J. • Sung, H.-I. • Tayar, J. • Treu, T. • Turner, C. S. • Uttley, P. • Van Saders, J. • Vican, L. • Villanueva, S., Jr. • Weiss, Y. • Woo, J.-H. • Yan, H. • Young, S. • Yuk, H. • Zheng, W. • Zhu, W. • Zu, Y.

Abstract • In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity-delay maps for the prominent broad emission lines (Lyα, C IV, He II, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity-delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He II response inside 5-10 lt-day has a broad single-peaked velocity profile. The Lyα, C IV, and Hβ responses extend from inside 2 to outside 20 lt-day, with double peaks at ±2500 km s^-1 in the 10-20 lt-day delay range. An incomplete ellipse in the velocity-delay plane is evident in Hβ. We interpret the maps in terms of a Keplerian disk with a well-defined outer rim at R = 20 lt-day. The far-side response is weaker than that from the near side. The line-center delay $\tau =(R/c)(1-\sin i)\approx 5$ days gives the inclination i ≍ 45°. The inferred black hole mass is M_BH ≍ 7 × 10⁷ M_☉. In addition to reverberations, the fit residuals confirm that emission-line fluxes are depressed during the "BLR Holiday" identified in previous work. Moreover, a helical "Barber-Pole" pattern, with stripes moving from red to blue across the C IV and Lyα line profiles, suggests azimuthal structure rotating with a 2 yr period that may represent precession or orbital motion of inner-disk structures casting shadows on the emission-line region farther out.

Links

• PREPRINT http://arxiv.org/abs/2003.01448
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2021ApJ...907...76H
• ELECTR https://doi.org/10.3847/1538-4357/abce60
• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2021ApJ...907...76H
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/abce60/pdf
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2021ApJ...907...76H
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2021ApJ...907...76H