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Transcript
Long Term Monitoring of Active Galactic Nuclei with Bell Astrophysical Observatory
Whitney Wills, Dr. Michael Carini, Dr. David Barnaby, Ashley Atkerson,
Wesley T. Ryle, Tala Monroe
Abstract
What is an AGN?
Active galactic nuclei (AGN) are some of the most energetic objects in the Universe. They are
composed of an ordinary elliptical galaxy with a super massive black hole at the center. A disk
of material, called an accretion disk, surrounds the super massive black hole, and jets of
material moving at nearly relativistic speeds are emitted perpendicular to the disk. In the BL
Lacertae class of AGN jets are pointed almost directly along the line of sight, resulting in large
amplitude, erratic brightness variations. Our primary goal is the monitoring of the brightness
variations of BL Lac objects and using these variations to investigate the physics at work in
these objects. BL Lacs are the most extreme example of an AGN with highly variable
continuum emission as one of their defining characteristics. We have undertaken a program to
monitor these continuum variations by using the Bell Observatory 0.6m telescope.
Undergraduate students run the sessions from WKU’s campus via the Internet or on-site. The
telescope is equipped with CCD camera, which is used to obtain data that is then transferred to
WKU’s campus where it is archived and analyzed by undergraduate students.
Take a normal Galaxy
At the center add:
1 supermassive Black Hole
(m=105-109 times mass of the sun)
1 accretion disk
2 relativistic jets of material
= 1 Active Galactic Nucleus (AGN)
Why Study BL Lac?
What is a BL Lac Object?
•Most extreme example of an AGN
Students at Work
•Highly variable continuum emission
at all wavelengths
External view of Bell
Observatory
•Featureless continuum means continuum
radiation is the only diagnostic
•They vary due to extremely highly
energetic physical processes
•Featureless optical spectra
•Variability is not regular, can’t get a few
cycles and be finished
•Highly variable polarization
•Verified aspect unified AGN model
Whitney Wills observing
onsite
Tala Monroe cleaning
mirror covers
Wes Ryle observing
remotely
Internal view of Bell
Observatory
Telescope Specifies
Telescope Status
•0.6m primary mirror, f/11
•Telescope is fully functional
•Manufactured by Group 128
•Remote and onsite observing capability
•Equatorial mount
•WKU undergraduate students routinely
operating telescope
•True Cassegrain
•Apogee Ap2p CCD camera
Acknowledgments
This project has been supported by NASA
the Kentucky Space Grant Consortium and
the Applied Research and Technology
Program at WKU
Data Reduction
Results
•Used Image Reduction and Analysis Facility
(IRAF) Software
•X-Ray and Optical light curve for MRK
501 have same trend
•Removed background and thermal noise from the
picture
•Observed and produced light curves for
40 BL Lac
•Removed non-linearity
•Trained 5 WKU students to observe
regularly
•Measured the brightness inside a circular aperture
centered on the star