Ralph B. Baldwin Professor of Astronomy
Mario Mateo observes the stars and motion of objects in nearby galaxies to assess the distribution of mass, particularly dark mass, within them. He has designed and built fiber spectrographs for Magellan that can analyze an unprecedented number of targets – more than 250 – at a time. His new Michigan/Magellan Fiber System (M2FS) is the most powerful yet and is ideal for studying objects’ chemical composition, mass, temperature, and motion. Mateo has recently completed an complementary spectroscopic capability, IFUM, that will uniquely among comparable instruments be able to carry out detailed spectroscopic studies simultaneously over entire astronomical objects such as dwarf galaxies, star-forming regions, star clusters and active galactic nuclei. These tools will allow UM and Magellan observers to carry out a wide range of key spectroscopic studies in many areas of study.
Mateo recently used his spectrographic data to challenge the paradigm of cold dark matter. A galaxy’s mass distribution is strongly reflected in the distribution of the speeds of its stars. So, to assess the dark-matter distribution in various dwarf galaxies, Mateo developed velocity dispersion profiles based on his sample of stellar speeds that was 100x larger than previously available. By plotting the spread in stars’ speeds as a function of their distance from the galaxy’s center, he and his collaborators have shown that the distribution of mass in these galaxies was not consistent with simple cold dark matter models.
Leading efforts to develop a fiber deployment strategies for large-scale spectroscopic surveys. Aiming to use IFUM to carry out detailed studies of dwarf galaxies beyond the Local Group and to explore the nature of active galaxies at high spectral resolution.
Background: BA, Rice University; PhD, University of Washington; Carnegie and Hubble Fellowships, Carnegie Observatory/Pasadena, CA.
Mario Mateo's biography.
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