GLOBULAR CLUSTER SYSTEMS IN BRIGHTEST CLUSTER GALAXIES: A NEAR-UNIVERSAL LUMINOSITY FUNCTION? Academic Article uri icon

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abstract

  • We present the first results from our HST Brightest Cluster Galaxy (BCG) survey of seven central supergiant cluster galaxies and their globular cluster (GC) systems. We measure a total of 48000 GCs in all seven galaxies, representing the largest single GC database. We find that a log-normal shape accurately matches the observed luminosity function (LF) of the GCs down to the GCLF turnover point, which is near our photometric limit. In addition, the LF has a virtually identical shape in all seven galaxies. Our data underscore the similarity in the formation mechanism of massive star clusters in diverse galactic environments. At the highest luminosities (log L > 10^7 L_Sun) we find small numbers of "superluminous" objects in five of the galaxies; their luminosity and color ranges are at least partly consistent with those of UCDs (Ultra-Compact Dwarfs). Lastly, we find preliminary evidence that in the outer halo (R > 20 kpc), the LF turnover point shows a weak dependence on projected distance, scaling as L_0 ~ R^-0.2, while the LF dispersion remains nearly constant.

authors

  • Harris, William Edgar
  • Morningstar, Warren
  • Gnedin, Oleg Y
  • O'Halloran, Heather
  • Blakeslee, John P
  • Whitmore, Bradley C
  • Côté, Patrick
  • Geisler, Douglas
  • Peng, Eric W
  • Bailin, Jeremy
  • Rothberg, Barry
  • Cockcroft, Robert
  • Barber DeGraaff, Regina

publication date

  • December 20, 2014