NOAO >   Observing Info >   Approved Programs >   2011B-0485

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Proposal Information for 2011B-0485


PI: Kailash Sahu, Space Telescope Science Institute, ksahu@stsci.edu
Address: SMO, 3700 San Martin Drive, Baltimore, MD 21218, USA

CoI: Howard Bond, STScI
CoI: Jay Anderson, STScI
CoI: Martin Dominik, U. of St. Andrews, UK
CoI: Andrzej Udalski, Warsaw University

Title: Detecting Isolated Black Holes through HST Astrometry and SMARTS Photometry of Microlensing Events

Abstract: The goal of this proposal is the first direct detection of isolated stellar-mass black holes (BHs). To date, stellar-mass BHs have only been detected in X-ray binaries. We have underway an \it HST project aimed at detecting single BHs through high-precision astrometry of long-duration MOA and OGLE microlensing events in the Galactic bulge. We select events where there is no contribution of light from the lens. Such events can only be produced by BH lenses, or by low-mass lenses that happen to move with unusually low relative velocities. To distinguish between them, we will use \it HST WFC3 imaging to search for the astrometric shift that only occurs in the case of a BH-mass lens. In a typical case, a BH lens will cause a position shift of \gtabout1.4 mas, detectable with WFC3 imaging. If the distance to the lens can also be inferred, through the effect of the Earth's motion on the microlensing light curve, the mass of the lens can be calculated directly. In addition to the \it HST astrometry, we require accurate photometric monitoring throughout the event in order to characterize the parallax effect. We request SMARTS 1.3m service observing which will, given the excellent observing conditions at CTIO, provide an essential adjunct to the monitoring carried out by the survey programs.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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