Broad-line Reverberation in the Kepler-field Seyfert Galaxy Zw 229-015

Barth, A.J.; Nguyen, M.L.; Malkan, M.A.; Filippenko, A.V.; Li, W.; Gorjian, V.; Joner, M.D.; Bennert, V.N.; Botyanszki, J.; Cenko, S.B.; Childress, M.; Choi, J.; Comerford, J.M.; Cucciara, A.; da Silva, R.; Duchêne, G.; Fumagalli, M.; Ganeshalingam, M.; Gates, E.L.; Gerke, B.F.; Griffith, C.V.; Harris, C.; Hintz, E.G.; Hsiao, E.; Kandrashoff, M.T.; Keel, W.C.; Kirkman, D.; Kleiser, I.K.W.; Laney, C.D.; Lee, J.; Lopez, L.; Lowe, T.B.; Moody, J.W.; Morton, A.; Nierenberg, A.M.; Nugent, P.; Pancoast, A.; Rex, J.; Rich, R.M.; Silverman, J.M.; Smith, G.H.; Sonnenfeld, A.; Suzuki, N.; Tytler, D.; Walsh, J.L.; Woo, J.-H.; Yang, Y.; Zeisse, C.

Abstract

The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from Hβ reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad Hβ flux. From cross-correlation measurements, we find that the Hβ light curve has a rest-frame lag of 3.86+0.69 –0.90 days with respect to the V-band continuum variations. We also measure reverberation lags for Hα and Hγ and find an upper limit to the Hδ lag. Combining the Hβ lag measurement with a broad Hβ width of σline = 1590 ± 47 km s–1 measured from the rms variability spectrum, we obtain a virial estimate of M BH = 1.00+0.19 –0.24 × 107 M ☉ for the black hole in Zw 229-015. As a Kepler target, Zw 229-015 will eventually have one of the highest-quality optical light curves ever measured for any active galaxy, and the black hole mass determined from reverberation mapping will serve as a benchmark for testing relationships between black hole mass and continuum variability characteristics in active galactic nuclei.

Citation

Barth, A., Nguyen, M., Malkan, M., Filippenko, A., Li, W., Gorjian, V., …Zeisse, C. (2011). Broad-line Reverberation in the Kepler-field Seyfert Galaxy Zw 229-015. Astrophysical Journal, 732(2), Article 121. https://doi.org/10.1088/0004-637x/732/2/121

• Journal Article Type: Article
• Acceptance Date: Mar 10, 2011
• Publication Date: May 10, 2011
• Deposit Date: Apr 6, 2014
• Publicly Available Date: Apr 20, 2016
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 732
• Issue: 2
• Article Number: 121
• DOI: https://doi.org/10.1088/0004-637x/732/2/121
• Public URL: https://durham-repository.worktribe.com/output/1456930