Masao Sako

Masao Sako
Standing Faculty

Professor and Undergraduate Chair

Research Areas: Observational Astronomy and Cosmology



           July 1, 2012 - Associate Professor, University of Pennsylvania

           2006-2012 - Assistant Professor, University of Pennsylvania

  • 9/2004 – 2006 — Postdoctoral Research Fellow, Stanford University
  • 9/2003 – 8/2004 — Chandra Postdoctoral Fellow, Stanford University
  • 9/2001 – 8/2003 — Chandra Postdoctoral Fellow, California Institute of Technology
  • 2/2001 – 8/2001 — Postdoctoral Research Scientist, Columbia Astrophysics Laboratory
  • 6/1997 – 2/2001 — Graduate Research Assistant, Columbia Un

2001 — Ph. D., Graduate School of Arts and Sciences, Columbia University
2000 — M. Phil., Graduate School of Arts and Sciences, Columbia University
1999 — M. A., Graduate School of Arts and Sciences, Columbia University
1995 — B. S., Fu Foundation School of Engineering and Applied Science, Columbia University

Research Interests

My research focuses on observational cosmology with supernovae (SNe). Measurements of luminosity distances to Type Ia SNe have shown that our Universe is dominated by an unknown component called "dark energy", which is causing the expansion of the Universe to accelerate. My group is involved in current (SDSS-II) and future (DES, SNAP, LSST) large-scale optical surveys that will discover many thousands of SNe that will be used to map out the detailed expansion history of our Universe. I am also interested in several aspects of high energy astrophysics including X-ray spectroscopy and observations of gamma-ray bursts, X-ray binaries, supermassive black holes, and clusters of galaxies.

Selected Publications
  • Sako, M., et al., "The Sloan Digital Sky Survey-II Supernova Survey: Search Algorithm and Follow-up Observations", The Astronomical Journal, submitted (2007)
  • Frieman, J. A., et al., "The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary", The Astronomical Journal, submitted (2007)
  • Sako, M., Harrison, F. A., & Rutledge, R. E., "A Search for Discrete X-ray Spectral Features in a Sample of Bright gamma-ray Burst Afterglows", The Astrophysical Journal, 623, 973 (2005)
    Soderberg, A. M., et al., "The sub-energetic GRB 031203 as a cosmic analogue to GRB 980425", Nature, 430, 648 (2004)
  • Watanabe, S., et al., "Detection of a Fully-resolved Compton Shoulder of the Iron K-alpha Line in the Chandra X-ray Spectrum of GX301-2", The Astrophysical Journal Letters, 594, 37 (2003)
  • Sako, M., et al., "Can a Dusty Warm Absorber Model Reproduce the Soft X-ray Spectra of MCG-6-30-15 and Mrk~766?", The Astrophysical Journal, 596, 114 (2003)
  • Sako, M., "CNO Line Radiation and the Bowen Fluorescence Mechanism in Optically-Thick, Highly-Ionized Media", The Astrophysical Journal, 594, 1108 (2003)
  • Kinkhabwala, A., et al., "XMM-Newton Reflection Grating Spectrometer Observations of Discrete Soft X-ray Emission Features in NGC1068", The Astrophysical Journal, 575, 732 (2002)