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Steps foward determination of the size and structure of the broad-line region in active galactic nuclei. V. Variability of the ultraviolet continuum and emission lines of NGC 3783

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Steps foward determination of the size and structure of the broad-line region in active galactic nuclei. V. Variability of the ultraviolet continuum and emission lines of NGC 3783

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Título Steps foward determination of the size and structure of the broad-line region in active galactic nuclei. V. Variability of the ultraviolet continuum and emission lines of NGC 3783
Autor Reichert, G.A.
Rodriguez-Pascual, P.M.
Alloin, Danielle Marie
Clavel, J.
Crenshaw, Daniel Michael
Kriss, Gerard A.
Krolik, J.H.
Malkan, M.A.
Netzer, Hagai
Peterson, Bradley M.
Wamsteker, W.
Pastoriza, Miriani Griselda
Altamore, A.
Altieri, B.
Anderson, K.S.J.
Blackwell, J.H., Jr.
Boisson, Catherine
Brosch, N.
Carone, T.E.
Dietrich, Matthias
England, M.N.
Evans, I.N.
Filippenko, Alexei V.
Gaskell, C.M.
Good, M.
Gondhalekar, P.M.
Horne, Keith
Kazanas, D.
Kollatschny, W.
Koratkar, A.P.
Korista, Kirk T.
Macalpine, G.M.
Maoz, D.
Mazeh, Tsevi
Mccollum, B.
Miller, Hugh Richard
Oliveira, Carlos Roberto Mendes de
O'Brien, P.T.
Pelat, D.
Pérez Jiménez, Enrique
Perola, G.C.
Pogge, Richard William
Ptak, R.L.
Recondo-Gonzalez, M.C.
Rodriguez-Espinosa, J.M.
Rosenblat, E.I.
Asadun, A.C.
Santos-Lleo, M.
Shields, J.C.
Shrader, C.R.
Shull, J.M.
Simkin, S.M.
Sitko, M.L.
Snijders, M.A.J.
Sparke, L.S.
Stirpe, Giovanna M.
Stoner, R.E.
Storchi-Bergmann, Thaisa
Sun, W.-H.
Wang, T.
Welsh, W.F.
White, R.J.
Winge, Claudia
Zheng, W.
Abstract We report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of 7 months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line ftuxes. The light curves for the con­ tinuum ftuxes exhibited two well-defined local mínima or "dips," the first lasting <~20 days and the second <~4 days, with additional episodes of relatively rapid ftickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became "harder" when brighter. The variations in the continuum occurred simultaneously at ali wavelengths (Δt < 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N v (which is relatively weak and badly blended with Lyα), the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or "lag." As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are consider­ ably shorter than those obtained for NGC 5548, with values of (formally) ~O days for He II +O III], and ~4 days for Lyα and C IV. The data further suggest lags of~4 days for Si IV+ O IV] and 8-30 days for Si III] +C III]. Mg II lagged the 1460 Å continuum by ~9 days, although this result depends on the method of measuring the line flux and may in fact be due to variability of the underlying Fe n lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over timescales of <~2 days, and that the character of the continuum variability may change with time.
Contido em The astrophysical journal. Chicago. Vol. 425, no. 2, pt. 1 (Apr. 1994), p. 582-608
Assunto Espectros astronômicos
Galáxia NGC 3783
Galáxia NGC 5548
Galaxias seyfert
Nucleo galatico
[en] Galaxies: active
[en] Galaxies: individual (NGC 3783)
[en] Galaxies: nuclei
[en] Galaxies: Seyfert
[en] Ultraviolet: galaxies
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/108841
Arquivos Descrição Formato
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