http://arxiv.org/abs/1711.09500
We present the first measurement of the globular cluster population surrounding the elliptical galaxy J07173724+3744224 ($z=0.1546$). This galaxy is located in the foreground in the field-of-view of the Hubble Space Telescope (HST) Frontier Fields observations of galaxy cluster MACS J0717.5+3745 ($z=0.5458$), and represents the third most-distant galaxy in which the globular cluster population has been examined. Based on deep HST ACS F435W, F606W, and F814W images, we find a total globular cluster population of $N_{tot}=3441\pm 1416$. Applying the appropriate extinction correction and filter transformation from ACS F814W to the Johnson V-band, we determine that the host galaxy has an absolute magnitude of $M_{V}=-22.2$. The specific frequency was found to be $S_{N}=4.5 \pm 1.8$. The radial profile of the globular cluster system was best fit using a powerlaw of the form $\sigma\sim R^{-0.6}$, with the globular cluster population found to be more extended than the halo light of the host galaxy ($\sigma_{halo}\sim R^{-1.7}$). The F435W-F814W colour distribution suggests a bimodal population, with red globular clusters $3\times$ more abundant than blue clusters. These results are consistent with the host elliptical galaxy J07173724+3744224 having formed its red metal-rich GCs in situ, with the blue metal-poor globular clusters accreted from low-mass galaxies.
N. Carlson, M. Sultanova, S. Vithanage, et. al.
Tue, 28 Nov 17
71/82
Comments: 11 pages, 13 figures, 1 table, submitted to MNRAS