Sarah Pearson

Graduate Student, Columbia University

Welcome to my homepage! I am a fourth year graduate student in the
Department of Astronomy at Columbia University


Here you can find a list of my refereed and submitted publications. You can also look me up on ADS, arXiv and google scholar.


Curriculum Vitae

I received my B.S. in Physics at the University of Copenhagen in 2012.

I'm currently a graduate student at Columbia University, where I am pursuing a Ph.D. advised by Kathryn V. Johnston, Mary E. Putman and Gurtina Besla.



I am interested in what we can learn about dark matter and galactic properties by studying tidal debris in our own and external galaxies. To investigate this, I use a combination of observations and simulations of Milky Way stellar tidal streams and dwarf galaxy interactions. I have previously done work on the morphology, explosive origin and ionization state of supernova remnants.


Modeling dwarf-dwarf interactions

In Pearson et al. (2016) we found that tidal interactions between dwarf galaxies could park gas at large distances, but that this gas would be re-accreted to the dwarfs (the gas remained bound) unless the pair was in the vicinity of a massive galaxy, which prevented the re-accretion. In this project, we use a hybrid of N-body and test particle simulations (Identikit: Barnes & Hibbard 2009) to investigate: how much gas is moved to the outskirts through tidal pre-processing and on what timescales does the gas fall back to the dwarfs? We do this by modeling a subset of the Pearson et al. (2016) pairs, which are pre-infall analogs of the Magellanic Clouds. This will help us understand the baryon cyle of dwarf galaxy interactions.



I modeled the dynamical evoltuion of the Milky Way globular cluster, Pal 5, and used the morphology of its stellar tidal stream to rule out a triaxial shape of the dark matter halo in the inner parts of our Galaxy. The Pal 5 stream formed large, two-dimensional "fans" when evolved in a triaxial halo, which is incosistant with observations. The stream properties were easily reproduced in a mildly oblate potential.

Dwarf-Dwarf Interactions

We studied resolved HI maps of a sample of 10 interacting dwarf irregular galaxy pairs at various interacting stages and in various environments within the Local Universe. We found that mutual interactions between the pairs can "park" (but not unbind) gas at large distances, and that only a nearby, massive galaxy prevents the gas from being re-accreted and ultimately removes the gas from the systems.

Supernova Remnants

Using observations from the Chandra X-ray Observatory, we found that the supernova remnant, W49B, originites from a jet-driven, core-collapse explosion of a massive star (Lopez, Ramirez-Ruiz, Castro & Pearson 2013) and that its plasma is overionized (the ions are stripped of more electrons than they should be a the given temperature) due to a rapid adiabatic expansion.




Department of Astronomy, Columbia University
Pupin Physics Lab, Office 1414
550 West 120th Street
New York, NY 10027