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Position: Research Assistant Professor, IACS,
Catholic University of America
Mail Address: NASA's Goddard Space Flight Center,
Code 681, Greenbelt, MD 20771
Office Location: GSFC, Bldg. 21, T21-A
Phone (GSFC): 301-286-0871
Fax (GSFC): 301-286-1752
Email: crenshaw@buckeye.gsfc.nasa.gov
Dr. Crenshaw is working on the optical and ultraviolet spectra of
active galaxies obtained by the Hubble Space Telescope
in support of the Instrument Definition Team for the
Space
Telescope Imaging Spectrograph. Current areas of interest include
the following:
1) Intrinsic UV absorption lines in active galaxies.
These lines are much more common than previously believed, and, along
with X-ray warm absorbers, reveal a component of high-ionization gas
that is outflowing from the active nucleus.
2) The size and structure of the broad-line region and continuum
cource (with the International
AGN Watch). IUE, HST/FOS, and ground-based monitoring campaigns
have revealed that emission line clouds in the broad-line region,
traveling at velocities of thousands of km/sec, are very close (light
days) to the central source (presumably a supermassive black hole). In
addition, observations of the continuum variability over a broad range
in wavelength (optical to X-rays) have been used to place strict
constraints on accretion disk and reprocessing models.
3) Physical conditions and kinematics of the narrow-line region
in Seyfert galaxies (with Dr. Steven Kraemer). This study is
important for understanding the extended region of gas that is ionized
by the central source, and the link between nuclear activity and the
host galaxy.
Preprint (in postscript)Preprint (in postscript)
Table 1a (in postscript)
Table 1b (in postscript)
Preprint (in postscript)Preprint (in postscript)|
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