Publication Date

April 2018


Edward Moran




English (United States)


On the whole, galaxies are not optically variable. However, the accretion disks of intermediate-mass black holes (IMBH) that reside at the centers of low-mass galaxies are known to display optical variability on time scales ranging from hours to years. One method of confirming the presence of an IMBH at the center of a low-mass galaxy would be to observe optical variability of the nucleus of the galaxy. Aperture photometry is ineffective at identifying this variability due to fluctuating distortions in the point source function (PSF) caused by changing atmospheric conditions, focus variations, and guiding errors. Instead we use image subtraction to identify optical variability. We developed an algorithm that improves the effectiveness of image subtraction techniques by reducing fluctuations in different images? PSFs. We used this technique to demonstrate variability in galaxies known to contain IMBHs which now allows us to use variability to search for IMBHs in low-mass galaxies via this technique. We have successfully identified IMBHs in two dwarf galaxies whose activity is ambiguous, J1401+51 and J1351+40.

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