Spatially resolved spectroscopy of the globular cluster RZ 2109 and the nature of its black hole

Mark B. Peacock, Stephen E. Zepf, Arunav Kundu, Thomas J. MacCarone, Katherine L. Rhode, John J. Salzer, Christopher Z. Waters, Robin Ciardullo, Caryl Gronwall, Daniel Stern

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16 Scopus citations


We present optical Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) spectroscopy of RZ 2109, a globular cluster (GC) in the elliptical galaxy NGC4472. This GC is notable for hosting an ultraluminous X-ray source as well as associated strong and broad [O III] λλ4959, 5007 emission. We show that the HST/STIS spectroscopy spatially resolves the [O III] emission in RZ 2109. While we are unable to make a precise determination of the morphology of the emission-line nebula, the best-fitting models all require that the [O III] λ5007 emission has a half-light radius in the range 3-7pc. The extended nature of the [O III] λ5007 emission is inconsistent with published models that invoke an intermediate-mass black hole origin. It is also inconsistent with the ionization of ejecta from a nova in the cluster. The spatial scale of the nebula could be produced via the photoionization of a strong wind driven from a stellar mass black hole accreting at roughly its Eddington rate.

Original languageEnglish (US)
Article number126
JournalAstrophysical Journal
Issue number2
StatePublished - Nov 10 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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