NOAO >   Observing Info >   Approved Programs >   2012A-0440

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Proposal Information for 2012A-0440


PI: Steve Zepf, Michigan State University, zepf@pa.msu.edu
Address: Dept. of Physics and Astronomy, East Lansing, MI 48824, USA

CoI: Matthew Steele, Michigan State University
CoI: Tom Maccarone, University of Southampton
CoI: Katherine Rhode, Indiana University
CoI: John Salzer, Indiana University
CoI: Arunav Kundu, Eureka Scientific

Title: A Search for Optical Emission Lines from the Globular Cluster Black- Hole Source CXOU1229410+075744

Abstract: We propose to obtain GMOS spectra of the newly discovered black-hole X-ray source CXOU1229410+075744 located in a globular cluster in the Virgo elliptical NGC 4472. To date there have only been two other black- hole X-ray sources in globular clusters for which it has been possible to obtain optical spectra. Both of these have proven to be remarkable. One of these, RZ2109, has extraordinarily broad [O III]4959, 5007 emission lines, with a line width of about 2,4000km/s in a globular cluster with an escape velocity about two orders of magnitude smaller. RZ2109 also shows no sign of other emission lines, requiring [O IIII]/H(beta) > 100. The second such object, CXOJ033831.8-352604, has much narrower line widths of about 140km/s, with [N II] as the strongest line, and also [O III] with no clear Balmer emission. Our goal is to obtain optical spectra of CXOU1229410+075744, the third such source for which spectroscopy is possible, in order to determine what the characteristic features of these objects and to begin to distinguish between models for how these accreting black hole systems are formed in the dense stellar systems in which they are observed.


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