NOAO >   Observing Info >   Approved Programs >   2009A-0204

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Proposal Information for 2009A-0204


PI: Steve Zepf, Michigan State University, zepf@pa.msu.edu
Address: Dept. of Physics and Astronomy, East Lansing, MI 48864, USA

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

Title: A GMOS Study [of the Optical Spectrum] of the Black Hole Hosting Globular Cluster RZ2109

Abstract: We propose to obtain GMOS spectra of the black hole-hosting globular cluster RZ2109. X-ray observations have shown that this globular cluster in the Virgo elliptical NGC 4472 hosts the only known black-hole X-ray binary in a globular cluster. Recently, we used exploratory Keck LRIS exposures at low spectral resolution (R ~ 400) to show that this globular cluster source has remarkably broad [OIII]4959, 5007 lines, with velocity widths of approximately 2,000km/s . Further, no other strong emission lines are observed, suggesting a large [OIII]/H(beta) ratio. Here we propose to obtain deep GMOS spectroscopy at significantly higher spectral resolution. We will use these data to - 1) determine the line profile of the broad [OIII]4959, 5007 lines. This is key for understanding the geometry of the [OIII] emitting region, 2) significantly improve the determination of the Balmer emission line luminosity and velocity width, using the higher spectral resolution and signal-to-noise to better characterize the underlying stellar Balmer absorption from the globular cluster stars, -3) either measure or place much more stringent limits on the line luminosities for other key diagnostic lines, such as [OIII]4363, and -4) test for variability in the [OIII]4959, 5007 emission lines by comparing the proposed data with the earlier exploratory observations.


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