On the emission-line response to continuum variations in the Seyfert galaxy NGC 5548

1990 ◽  
Vol 365 ◽  
pp. L5 ◽  
Author(s):  
Hagai Netzer ◽  
Dan Maoz
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Ngc 5548

scholarly journals Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Markarian 6

2013 ◽  
Vol 9 (S304) ◽  
pp. 407-408
Author(s):  
Norayr S. Asatrian
Keyword(s):  
Fine Structure ◽  
Emission Line ◽  
Sampling Rate ◽  
Seyfert Galaxy ◽  
Special Astrophysical Observatory ◽  
Balmer Line ◽  
Line Profiles ◽  
Balmer Lines ◽  
Profile Changes ◽  
Hydrogen Emission Line

AbstractPart of results of the multi-epoch intranight optical spectroscopic monitoring of the Markarian 6 nucleus carried out at the telescopes of 6-m of the Special Astrophysical Observatory (Russia), 2.6-m of the Byurakan Astrophysical Observatory (Armenia) and 2-m of the Tautenburg Observatory (Germany) is presented.Observations were made in 1979, 1986, 1988-1991 and 2007-2009 during a total of 33 nights with an average sampling rate of 4 spectra per night. TV-scanner and long-slit spectrographs equipped with Image Tube and CCD detector arrays were used. Altogether we analyzed 110 Hβ and 58 Hα region spectra to search for intranight variability in the broad hydrogen emission line profiles. The typical spectral resolutions were 4 Å for scanner spectra, 6 Å for photographic spectra, and 5 Å and 10 Å for CCD spectra. The S/N ratio at the continuum level near the Hβ and Hα lines was in the range 15–50.The purpose of the search was to look for the characteristic variability signatures of different kinematical models of the broad emission-line region. We considered the centering and guiding errors which can result in differences between spectra.We found variations in the broad Balmer line difference profiles on time scale of hour with the level of significance of 3.6 σ to 5.0 σ. Variations take the form of narrow, small bumps located at the blue and red sides or only at the blue side of the lines. In the intermediate level of broad line flux, the Hβ and Hα profiles show fine structure. Detected profile changes occurred at the same radial velocity shifts as the details in the fine structure.The variability is at least 2 orders of magnitude more rapid than any observed for broad Balmer line profiles in AGNs that we are aware of in the literature.Discovered extremely rapid line-profile variability may be associated with reverberation effects. Two-sided profile changes may indicate the response of circularly rotating hydrogen clouds in the BLR to a light pulse from a central source. One-sided profile variations may be attributed to a response of a non-disk component: the subarcsec scale region of the jet.

Radio Emission from the Seyfert Galaxy NGC 5548

1982 ◽  
pp. 191-192
Author(s):  
J. S. Ulvestad ◽  
A. S. Wilson ◽  
D. G. Wentzel
Keyword(s):  
Radio Emission ◽  
Seyfert Galaxy ◽  
Ngc 5548

High Velocity Outflow in the Extended Emission-Line Region of the Seyfert Galaxy NGC 7319

1996 ◽  
Vol 111 ◽  
pp. 140 ◽  
Author(s):  
Kentaro Aoki ◽  
Hiroshi Ohtani ◽  
Michitosh Yoshida ◽  
George Kosugi
Keyword(s):  
Emission Line ◽  
High Velocity ◽  
Seyfert Galaxy ◽  
Line Region ◽  
Extended Emission

The discovery of an O VII emission line in the ASCA spectrum of the Seyfert galaxy NGC 3783

1995 ◽  
Vol 438 ◽  
pp. L67 ◽  
Author(s):  
I. M. George ◽  
T. J. Turner ◽  
H. Netzer
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy

scholarly journals Variability of the Ultraviolet Continuum and Emission Lines of NGC 3783

1994 ◽  
Vol 159 ◽  
pp. 403-403
Author(s):  
G.A. Reichert
Keyword(s):  
Seyfert Galaxy ◽  
Light Curves ◽  
Emission Lines ◽  
Power Density Spectrum ◽  
Ultraviolet Continuum ◽  
Density Spectrum ◽  
International Ultraviolet Explorer ◽  
Monitoring Effort ◽  
Ngc 5548 ◽  
The Continuum

On behalf of the International AGN Watch, I 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 seven 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 fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or “dips,” the first lasting ≲ 20 days and the second ≲ 4 days, with additional episodes of relatively rapid flickering 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 all 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 considerably shorter than those obtained for NGC 5548, with values of (formally) ∼ 0 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]. Uncertainties in these quantities are likely to be of order 2–3 days for the stronger features (Lyα, C IV), and 3–4 days for the weaker ones (He II+O III], Si IV+O IV], 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 II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over time scales of ≲ 2 days, and that the character of the continuum variability may change with time.

Deep Optical Imaging of the Bright Seyfert Galaxy NGC 5548: A Long, Very Low Surface Brightness Tail

1998 ◽  
Vol 116 (1) ◽  
pp. 102-110 ◽  
Author(s):  
J. Anthony Tyson ◽  
Philippe Fischer ◽  
Puragra Guhathakurta ◽  
Peter McIlroy ◽  
Richard Wenk ◽  
...  
Keyword(s):  
Optical Imaging ◽  
Surface Brightness ◽  
Seyfert Galaxy ◽  
Low Surface Brightness ◽  
Ngc 5548

scholarly journals The extended emission-line region of the Seyfert galaxy Mrk 573

1999 ◽  
Vol 309 (1) ◽  
pp. 1-25 ◽  
Author(s):  
P. Ferruit ◽  
A. S. Wilson ◽  
H. Falcke ◽  
C. Simpson ◽  
E. Pecontal ◽  
...  
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Line Region ◽  
Extended Emission
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