Matthew G. Walker
Astrophysics & Cosmology
Wean Hall 8408
Education & Professional Experience
PhD: University of Michigan (2007)
American Astronomical Society
Honors and Awards:
Martin and Beate Block Award, Aspen Center for Physics (2013)
Hubble Post-doctoral Fellowship (2010)
Assistant Professor, Carnegie Mellon University, 2013–
Post-doctoral Research: Harvard University, 2010–13
Post-doctoral Research: University of Cambridge (U.K.), 2007–10
I study the astrophysical properties of dark matter, thus far via optical imaging, spectroscopy and dynamical modelling of the 'dwarf' galaxies that surround the Milky Way and neighboring Andromeda. The dwarf galaxies include the oldest, smallest and 'darkest' (i.e., composed almost entirely of dark matter) galaxies known, and currently represent the smallest physical scales (sizes of ≈ 100 light years, speeds of a few kilometers per second, masses of ≈ 100,000 Suns) that are associated empirically with dark matter. If dark matter is made from some kind of new fundamental particle, then the manner in which dark matter can form 'clumps' at such small scales can help to decide among various ideas about the properties of that particle. By measuring the spatial distribution of dark matter in dwarf galaxies, I aim to help figure out what the dark matter actually is. Thus my research has wandered into the intersection of dynamics, cosmology and particle physics.
Night sky at the Magellan telescopes of Las Campanas Observatory, Chile.
(Photography and video editing by Mike Padilla, @mrpadillaphotography).
Tucker, Evan; Walker, Matthew G.; Mateo, Mario; Olszewski, Edward W.; Bailey, John I., III; Crane, Jeffrey D.; Shectman, Stephen A., Magellan/M2FS Spectroscopy of Galaxy Clusters: Stellar Population Model and Application to Abell 267, The Astronomical Journal 154, 3 (2017)
Nelson Caldwell, Matthew G. Walker, Mario Mateo, Edward W. Olszewski, Sergey Koposov, Vasily Belokurov, Gabriel Torrealba, Alex Geringer-Sameth, and Christian I. Johnson, Crater 2: An Extremely Cold Dark Matter Halo, The Astrophysical Journal 839, 1 (2017)
Alex Geringer-Sameth, Matthew G. Walker, Savvas M. Koushiappas, Sergey E. Koposov, Vasily Belokurov, Gabriel Torrealba, N. Wyn Evans, Indication of Gamma-Ray Emission from the Newly Discovered Dwarf Galaxy Reticulum II, Physical Review Letters 115, 81101 (2015)
Walker, Matthew G.; Mateo, Mario; Olszewski, Edward W.; Bailey, John I., III; Koposov, Sergey E.; Belokurov, Vasily; Evans, N. Wyn, Magellan/M2FS Spectroscopy of the Reticulum 2 Dwarf Spheroidal Galaxy, The Astrophysical Journal 808, 2 (2015)
Jorge Peñarrubia, Andrew Pontzen, Matthew G. Walker, Sergey E. Koposov, The coupling between the core/cusp and missing satellite problems, The Astrophysical Journal 759, L42 (2012)
Matthew G. Walker, Jorge Peñarrubia, A method for measuring (slopes of) the mass profiles of dwarf spheroidal galaxies, The Astrophysical Journal 742, 20 (2011)
Matthew G. Walker, Mario Mateo, Edward W. Olszewski, Jorge Peñarrubia, N. Wyn Evans, Gerard Gilmore, A universal mass profile for dwarf spheroidal galaxies?, The Astrophysical Journal 704, 1274 (2009)