Active Galactic Nuclei
NGC 1566 pictured above is an example of a Seyfert galaxy. It has a bright
point, central nucleus whose spectrum shows charactistic broad emission lines.
The lines are attributed to gas moving at velocities of thousands of km/s
aound a supermassive black hole. The picture was taken on the UK Schmidt Telescope
Much of my work on Active Galactic Nuclei for the past several years has
been in collaboration with my former graduate student Alex Filippenko (U.C.
Berkeley and
his former students (and, therefore, my grandchildren) L. Ho (OCIW)
and A. Barth (CfA). Our major work was a survey of the nuclei
of the brightest 500 galaxies north of the celestial equator using
sectra obtained with the Double Spectrograph on the Hale 200 inch telescope at the Palomar Observatory . This survey, which was started
when Filippenko was my student in 1984 and completed in 1998, took about 50
clear nights and could only have been done by people with priviledged
access to a large telescope. Click here to see a figure from the paper by Ho, Filippenko, Peng and Sargent referred to below. It shows typical examples of how the
H alpha and [N II] lines were decomposed into broad and sharp components
in order to reveal the broad H alpha emission line characteristic of a
Seyfert I galaxy.
Some of our papers are listed below:
- A. J. Barth, L. C. Ho, A. V. Filippenko, and W. L. W. Sargent, 1998, A Search for Ultraviolet Emission from LINERs , Astrophysical Journal 496, 133.
- L. C. Ho, A. V. Filippenko, W. L. W. Sargent and C. Y. Peng, 1997, A Search for ``Dwarf'' Seyfert Nuclei. V. Demographics of Nuclear Activity in Nearby Galaxies ,
Astrophysical Journal 487, 568.
- L. C. Ho, A. V. Filippenko, and W. L. W. Sargent, 1997,
The Influence of Bars on Nuclear Activity , Astrophysical Journal 487, 591. (The unintentional humour of the title won this paper a
mention in The Journal of Irreproducable Results .)
- L. C. Ho, A. V. Filippenko, and W. L. W. Sargent, 1997, Properties of H II Regions in the Centers of Nearby Galaxies , Astrophysical Journal 487, 579.
- L. C. Ho, A. V. Filippenko, W. L. W. Sargent and C. Y. Peng, 1997,
A Search for ``Dwarf'' Seyfert Nuclei. IV. Nuclei with Broad H$\alpha$
Emission , Astrophysical Journal Supplements 112, 391.
- L. C. Ho, A. V. Filippenko and W. L. W. Sargent, 1997, A Search for ``Dwarf'' Seyfert Nuclei. III. Spectroscopic Parameters
and Properties of the Host Galaxies , Astrophysical Journal Supplements 112, 315.
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page by Wallace Sargent, last updated 19 May 1999