Mario Mateo

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University of Michigan Department of Astronomy
1085 S. University
Ann Arbor, MI 48109

Office Location(s): 303C West Hall
Phone: 734.936.1742
Fax: 734.763.6317
Research Website

  • About

    Mario Mateo observes the stars and motion of objects in nearby galaxies to assess the distribution of mass, particularly dark mass, within them. He is a ground-breaking instrumentalist, who 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. It has uniquely positioned Mateo’s group to follow up on the deluge of new detections expected from sky surveys like the LSST, Dark Energy Survey, and SkyMapper. Student Jeb Bailey plans to use it to study hot Jupiters, and Mateo plans to explore the evolution of dwarf galaxies and their interactions with the Milky Way.

    Notable Results

    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.

    New Directions

    Leading efforts to develop a Southern Spectroscopic Survey Telescope (SSST), a dedicated spectroscopic complement to the large-scale photometric surveys of the Southern Sky.                                             


    BA, Rice University; PhD, University of Washington; Carnegie and Hubble Fellowships, Carnegie Observatory/Pasadena, CA.


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