Graduation Year


Graduation Month


Document Type

Professional Paper

Degree Name

Bachelor of Arts

School or Department

Physics and Astronomy


Physics – Astronomy

Faculty Mentor Department

Physics and Astronomy

Faculty Mentor

Dr. Nate McCrady


astronomy, black hole, reverberation mapping, active galactic nucleus, emission line

Subject Categories

Cosmology, Relativity, and Gravity | External Galaxies


Quasars are among the most luminous objects in the Universe, and the mechanism behind their luminosity was shrouded in mystery decades after their discovery. Since then, we have found that these objects are active galactic nuclei (AGN), which are powered by actively-feeding super massive black holes at the center of a galaxy. But we still know fairly little about the structure and motion of the material surrounding active super massive black holes, and most of these objects are not resolvable by conventional observations. We use a technique called reverberation mapping, which is traditionally used only as a mass determination method, to probe the structure and kinematics of dozens of AGN. Reverberation mapping uses the time lag between a change in continuum flux and a change in emission line flux to gauge the size of the broad line region (based on light travel time). We combine that size with the emitting material’s spread in velocity (measured from the width of the emission line) to determine the mass of the super massive black hole. We then repeat that process for sections of the emission line with equal flux, producing a velocity-resolved time delay graph, which we can analyze to visualize how material around the black hole moves. I present detailed analysis for the object Markarian 841.

Honors College Research Project


GLI Capstone Project




© Copyright 2021 Samuel J. Schonsberg