NASA’s Astrophysics Theory Program (ATP) has awarded our team (PI Robyn Sanderson, co-PI Andrew Wetzel) a grant for Predicting observable signatures for dynamical interactions between dark-matter substructure and stellar streams in the Milky Way. Congratulations to Robyn Sanderson, who led this grant!
The wealth of ongoing and upcoming observations of the Milky Way promise an era of ‘near-field cosmology’ to test the cold dark matter (CDM) paradigm. One of the most exciting and powerful probes of dark matter is using the Milky Way’s stellar streams as ‘gravitational antennae’, as close passages of small dark-matter subhalos dynamically perturb cold stellar streams, allowing us to test the diverging predictions of different dark-matter models for the low-mass end of the (sub)halo mass function. Our goal with this grant is to use our Latte suite of FIRE-2 simulations of Milky Way-like galaxies to model the dynamics of dark-matter subhalo interactions with stellar streams from disrupted globular clusters and satellite galaxies in realistic detail, including creating synthetic observations of these simulated perturbed streams. Our goal is to provide the first comprehensive end-to-end study that connects cosmological predictions from baryonic simulations to interpretations of, and predictions for, observable perturbations from dark-matter subhalos on stellar streams.
We are so excited that Sarah Loebman has accepted a faculty position at the University of California, Merced, where she will start as an Assistant Professor in their Department of Physics in fall 2020! We are doubly excited because, as their first astrophysics faculty, Sarah will start a new astrophysics program within their department. Fortunately for us, she will stay with our group at UC Davis for another year to finish her Hubble Fellowship. Congratulations Sarah!!!
co-investigators: Jay Anderson, Gurtina Besla, Mike Boylan-Kolchin, Tom Brown, James Bullock, Andrew Cole, Michelle Collins, Mike Cooper, Alis Deason, Andrew Dolphin, Aaron Dotter, Mark Fardal, Annette Ferguson, Tobias Fritz, Marla Geha, Karoline Gilbert, Raja Guhathakurta, Rodrigo Ibata, Michael Irwin, Myoungwon Jeon, Evan Kirby, Geraint Lewis, Dougal Mackey, Steve Majewski, Nicholas Martin, Alan McConnachie, Ekta Patel, Mike Rich, Josh Simon, Evan Skillman, Tony Sohn, Erik Tollerud, Roeland van der Marel
a Hubble Space Telescope (HST) Legacy Theory grant for Probing the epoch of reionization with the fossil record of nearby dwarf galaxies. Our goal is to use our FIRE-2 simulations to rigorously test and characterize how well HST near-field observations of the star-formation histories of dwarf galaxies in the Local Group can measure the faint end of the galaxy ultra-violet luminosity function during the epoch of reionization at z ~ 7. Furthermore, we will create synthetic HST and JWST observations of these simulated dwarf galaxies, to quantify how accurately the SFHs from measured stellar populations in nearby dwarfs can infer their star formation rates and UV luminosities at z ~ 7, and we will release these synthetic observations and simulation data to the scientific community, to help leverage existing HST data and guide upcoming JWST observations.
The Hellman Fellows Program has selected me as a 2019 Hellman Fellow, for my proposed research program: Using stars as gravitational antennae to measure dark matter. The Hellman Fellows Program supports the research of assistant professors, and this fellowship grant will help support the work of our group to use our Latte FIRE simulations to develop new dynamical models to measure the nature of dark matter, by using streams of stars as ‘gravitational antennae’ for interactions with dark-matter subhalos, thus translating dark-matter theories directly into measurable predictions for stellar dynamics.
I am excited that the Heising-Simons Foundation selected the grant that Keith Hawkins, Jennifer van Saders, and I submitted during this meeting: Aging Gracefully: Stellar Ages Across the HR Diagram and Their Implications for Galactic Archaeology. With this seed funding, our goal is two-fold:
Use the Latte FIRE-2 Milky Way-like simulations as a testbed to quantify the observational precision in stellar ages that we require for specific Milky Way studies.
Compile a unified framework for combining/comparing different ways of measuring stellar ages in an easy-to-use Baysian framework.
I am excited to work with Keith and Jen on this project over the next year!
Sierra Chapman, who has been pursuing research with our group as part of her Honor’s Thesis, graduates with her bachelor’s degree in physics. Moreover, for her excellent work on her Honors Thesis, in which she predicts the population of low-mass dark-matter subhalos that orbit close to the Milky Way, she earned Highest Honors. Sierra will continue to work with us over the summer to translate her thesis work into a paper to submit for publication. Congratulations Sierra!
Excited to announce the first student-led paper from our group, led by Ph.D. student Jenna Samuel: A profile in FIRE: resolving the radial distributions of satellite dwarf galaxies in the Local Group with simulations. Jenna examined the radial distribution of satellite dwarf galaxies around MW/M31-mass hosts in our FIRE simulations, which she showed are consistent with the Local Group. The satellites of MW-like galaxies from the SAGA survey have 2D radial profiles that are similar to our simulations too. Interestingly, more massive host galaxies have fewer satellites at small distances, which is caused by tidal destruction from the central galaxy. Jenna also quantified the destruction of subhalos by comparing our baryonic simulations to their dark matter-only versions, finding 10x destruction within the inner 20 kpc. Finally, Jenna applied approximations of observational completeness in the LG to our simulations, predicting that there may be 2-10 satellites with stellar mass > 10^5 Msun to be discovered around the MW, and 6-9 around M31. Congratulations to Jenna for such a good first paper!