Long Term Monitoring of Active Galactic Nuclei with Bell Astrophysical Observatory

1. 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 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. What is an AGN? 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? • Featureless continuum means continuum radiation is the only diagnostic • They vary due to extremely highly energetic physical processes • Variability is not regular, can’t get a few cycles and be finished • Verified aspect unified AGN model • What is a BL Lac Object? • Most extreme example of an AGN • Highly variable continuum emission at all wavelengths • Featureless optical spectra • Highly variable polarization Students at Work External view of Bell Observatory Whitney Wills observing onsite Tala Monroe cleaning mirror covers Wes Ryle observing remotely Internal view of Bell Observatory • Telescope Specifies • 0.6m primary mirror, f/11 • Manufactured by Group 128 • Equatorial mount • True Cassegrain • Apogee Ap2p CCD camera • Telescope Status • Telescope is fully functional • Remote and onsite observing capability • WKU undergraduate students routinely operating telescope • Data Reduction • Used Image Reduction and Analysis Facility (IRAF) Software • Removed background and thermal noise from the picture • Removed non-linearity • Measured the brightness inside a circular aperture centered on the star • Results • X-Ray and Optical light curve for MRK 501 have same trend • Observed and produced light curves for 40 BL Lac • Trained 5 WKU students to observe regularly Acknowledgments This project has been supported by NASA the Kentucky Space Grant Consortium and the Applied Research and Technology Program at WKU