Sean Fillingham, UC Irvine

About Me

I am a physics PhD candidate at the University of California, Irvine working with Prof. Michael Cooper. Collaborators include but are not limited to Prof. James Bullock and the Local Group.

Research Interests

My research interests generally focus on galaxy evolution. At the moment the majority of my work is trying to understand the interaction between a satellite galaxy and its host environment. Some of the specific questions my work is trying to address are: How do galaxies evolve in overdense environments? What physical processes act to shut down star formation in satellites around massive hosts? Are the local (z~0) observed environmental trends the same at higher redshift and what can we learn from these trends as a function of redshift?

Satellite Quenching Model

One of the primary results of our groups work has been a quenching model based on the accretion histories of subhalos in N-body simulations, that is broadly consistent with observations. Below is a "cartoon" picture that illustrates the important quenching mechanisms in each satellite stellar mass regime.

First Author Publications

Taking Care of Business in a Flash: Constraining the Time-Scale for Low-Mass Satellite Quenching with ELVIS

This work uses the distribution of satellite galaxies in the Local Group to infer a typical quenching timescale through comparison to the accretion histories of subhalos in dark matter only simulations. We find that the extremely high fraction of quenched satellites within 300 kpc of either the Milky Way or M31 necessitates a relatively low quenching timescale of 2 Gyr. This very short quenching timescale points towards ram-pressure stripping as the quenching mechanism, or any other mechanism which operates on roughly a dynamical timescale. Additionally, we demonstrate that higher mass satellite galaxies have quenching timescales that are consistent with starvation as the dominant mechanism.


Under Pressure: Quenching Star Formation in Low-Mass Satellites via Stripping

This work is the extension of the TCB paper. Here we explicitly investigate the effectiveness of stripping, both ram pressure and viscous, as the dominant quenching mechanism in low mass satellites. Our implementation of stripping is able to reproduce the quenching critical mass for a variety of host halo properties, however the overall strength is unable to fully remove the cold gas component of the dwarfs galaxies below the critical mass. As such, stripping likely requires the assistance of internal feedback from the extra burst of star formation that is likely induced as the dwarf galaxy begins to interact with the host halo gas. Overall, ram-pressure and viscous stripping are viable candidate quenching mechanisms in the low mass galaxy regime, however additional hydrodynamic modeling is needed to confirm the overall effectiveness when stellar feedback is included.


Nth Author Publications

Discovery and Follow-Up Observations of the Type Ia Supernova SN 2016COJ WeiKang, Z., Mauerhan, J., Graham, M., et al. (in prep)


Get In Touch

Please contact me with any questions, comments, or concerns you might have with my past or present work. Snide remarks are also highly encouraged...

  • Address

    2137 Frederick Reines Hall
    University of California
    Irvine, CA 92617
    United States
  • Email

    sfilling [at] uci [dot] edu