Space Telescope and Optical Reverberation Mapping Project. I. Ultraviolet observations of the Seyfert 1 galaxy NGC 5548 with the cosmic origins spectrograph on Hubble Space Telescope
- Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Department of Physics and Astronomy, Georgia State University, 25 Park Place, Suite 605, Atlanta, GA 30303 (United States)
- SUPA Physics and Astronomy, University of St. Andrews, Fife, KY16 9SS Scotland (United Kingdom)
- Department of Physics, Western Michigan University, 1120 Everett Tower, Kalamazoo, MI 49008-5252 (United States)
- School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)
- Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretana N 1111, Playa Ancha, Valparaíso (Chile)
- Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States)
- Department of Astronomy and Astrophysics, Eberly College of Science, Penn State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
- Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom)
- Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand)
- Dipartimento di Fisica e Astronomia “G. Galilei,” Università di Padova, Vicolo dell’Osservatorio 3, I-35122 Padova (Italy)
We describe the first results from a six-month long reverberation-mapping experiment in the ultraviolet based on 171 observations of the Seyfert 1 galaxy NGC 5548 with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Significant correlated variability is found in the continuum and broad emission lines, with amplitudes ranging from ∼30% to a factor of two in the emission lines and a factor of three in the continuum. The variations of all the strong emission lines lag behind those of the continuum, with He ii λ1640 lagging behind the continuum by ∼2.5 days and Lyα λ1215, C iv λ1550, and Si iv λ1400 lagging by ∼5–6 days. The relationship between the continuum and emission lines is complex. In particular, during the second half of the campaign, all emission-line lags increased by a factor of 1.3–2 and differences appear in the detailed structure of the continuum and emission-line light curves. Velocity-resolved cross-correlation analysis shows coherent structure in lag versus line of sight velocity for the emission lines; the high-velocity wings of C iv respond to continuum variations more rapidly than the line core, probably indicating higher velocity broad-line region clouds at smaller distances from the central engine. The velocity-dependent response of Lyα, however, is more complex and will require further analysis.
- OSTI ID:
- 22883057
- Journal Information:
- Astrophysical Journal, Vol. 806, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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