Research



My research concentrates primarily on Active Galactic Nuclei (AGN).  An AGN consists of a super-massive black hole (weighing in at several million if not billions of times the mass of the sun) embedded in the heart of a host galaxy. This black hole is surrounded by an equatorial accretion disk of in-falling material.  In the objects I study, this accretion disk also fuels a columnized, relativistic jet of ionized gas and dust, formed through interactions with the black hole's powerful magnetic field and released perpendicular to the disk (see diagram).

An AGN in which the jet is oriented along the line of sight to the observer (in other words, we happen to be looking right down the barrel of the gun) is called a blazar.  Observationally, blazars have many distinguishing characteristics, including a double peaked spectral energy distribution (SED), a strong presence in the radio and gamma ray regimes, significant optical polarization, and not least, extreme brightness variability on all time scales, from months and years to mere days or even hours

Historically, blazars have always been found in elliptical galaxies, which I have always thought strange -- are we really expected to believe that an AGN somehow "knows" that it is not allowed to point a jet in the direction of Earth if it happens to be hosted by a spiral galaxy?  Thus, it came as little surprise to me when other research groups began finding AGNs in spiral host galaxies that exhibited characteristics similar to those listed above.

Groups such as those lead by Foschini and Yuan have demonstrated that certain very radio loud, narrow-line Seyfert 1 galaxies clearly possess blazar-like properties.  Building on such work, I have been examining similar objects for signs of microvariability (brightness variations on timescales of a few minutes or hours) and attempting to characterize it if found.  At the very least, these observations will help confirm the blazar-like nature of these Seyfert galaxies.  However, it is my hope to find that the presence or non-detection of microvariability will correlate with some other, more easily observed property, allowing other astronomers to be able to avoid the lengthy observation times necessary for such measurements.

To this end, I and fellow graduate student Joe Eggen (who is researching the changing optical polarization and gamma ray behavior of these same target objects) have constructed a list of several dozen narrow-line Seyfert 1 galaxies with varying degrees of radio loudness, redshift, gamma-ray detection, etc.  and have been attempting to parametrize their behavior.  Observations of these objects have been obtained from the 31-inch NURO, 42-inch Hall, and 72-inch Perkins telescopes at the Lowell Observatory in Flagstaff, AZ.  I have also acquired data from the 1.3 meter telescope at the Cerro Tololo Interamerican Observatory (CTIO) in Chile through the SMARTS consortium. I typically receive about one week's worth of data out of every month, allowing for the construction of very well defined optical light curves on multiple time scales. Results for one of our more spectacular objects can be found here.


Finding charts hosted on this website were constructed by myself for ease of use in differential photometry, and are made freely available to the community.  I ask only that they be referenced to should you wish to use them.  All apparent magnitudes listed for comparison stars in the object fields of view were calibrated using the Landolt list of equatorial stars. Images for the finding charts were obtained from the Sloan Digital Sky Survey (SDSS) through the use of their online tools.


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