At the heart of every galaxy lives a supermassive black hole many thousands to billions of times the mass of our sun.  Often, the black hole lies dormant, but when material wanders too close, it forms an accretion disk as it falls into the black hole.  This accretion disk heats up due to friction and emits an enormous amount of energy in the form of light-- this is what we call an active galactic nucleus, or AGN.  AGN can be bright enough to outshine an entire galaxy, and can potentially drive winds capable of clearing gas from the galaxy.  Devoid of gas, a galaxy will lack the raw materials required to form stars, and will passively age instead of growing in stellar mass.  Using high resolution, spatially resolved spectra collected from the Low Resolution Imaging Spectrometer (LRIS) in the Keck telescope on Mauna Kea, I study the interplay between AGN and the gas in their host galaxies.

In the same way that ancient navigators used stars to track their journeys across the Earth, we now use careful position (astrometric) measurements of distant quasars to orient ourselves as Earth travels through the Universe.  A global network of radio telescopes form a very long baseline interferometer (VLBI) capable of recording extremely precise astrometric measurements of quasars billions of light years away.  A sophisticated modeling and estimation software then holds the positions of all distant objects fixed, corrects for the orbit, precession, nutation, and tectonic activity of the Earth, and generates an extremely precise celestial reference frame.  This reference frame is recognized as the international standard and is used to calibrate GPS, track spacecraft, and detect tectonic motions with precision greater than 1mm/year.  

Drawing from this large database containing decades of astrometric data, I modified the code to instead produce time series data describing the astrometric positions of 50 individual quasars.  I then searched for correlated deviations in each quasar's position and used statistical tests to determine whether those positional shifts could have been caused by gravitational lensing by a black hole in the halo of our galaxy.  

Dark, avalanche-like streaks actively appear and fade on dust-covered slopes on Mars.  Researchers have proposed a number of triggering mechanisms that could cause slope streaks, from dry-material avalanches triggered by geologic activity, wind, or overly-steepened slopes.  Other proposed mechanisms involve liquid water lurking just beneath the Martian surface.   If slope streaks were primarily caused by subsurface water flows, we might expect to see streaks form more often in the summer than the winter time.  For my undergraduate research project, I studied the seasonality of Martian slope streaks in order to address this question.