Abell 1689 中超紧致矮星系：基于 ACS 的光度研究
摘要
investigate the properties of Ultra Compact Dwarf (UCD) galaxy candidates in Abell 1689 (z=0.183) based on deep high resolution ACS images. A UCD candidate has to be unresolved, have i<28 (M_V<-11.5) mag and satisfy color limits derived from Bayesian photometric redshifts. We find 160 UCD candidates with 22<i<28 mag. It is estimated that about 100 of these are cluster members, based on their spatial distribution and photometric redshifts. For i>26.8 mag, the radial and luminosity distribution of the UCD candidates can be explained well by Abell 1689's globular cluster (GC) system. For i<26.8 mag, there is an overpopulation of 15 +/- 5 UCD candidates with respect to the GC luminosity function. For i<26 mag, the radial distribution of UCD candidates is more consistent with the dwarf galaxy population than with the GC system of Abell 1689. The UCD candidates follow a color-magnitude trend with a slope similar to that of Abell 1689's genuine dwarf galaxy population, but shifted fainter by about 2-3 mag. Two of the three brightest UCD candidates (M_V ~ -17 mag) are slightly resolved. At the distance of Abell 1689, these two objects would have King-profile core radii of ~35 pc and r_eff ~300 pc, implying luminosities and sizes 2-3 times those of M32's bulge. Additional photometric redshifts obtained with late type stellar and elliptical galaxy templates support the assignment of these two resolved sources to Abell 1689. Our findings imply that in Abell 1689 there are at least 10 UCDs with M_V<-12.7 mag. Compared to the UCDs in the Fornax cluster they are brighter, larger and have colors closer to normal dwarf galaxies. This suggests that they may be in an intermediate stage of the stripping process. Spectroscopy is needed to definitely confirm the existence of UCDs in Abell 1689.
关键词
引用
@article{arxiv.astro-ph/0406613,
title = {Ultra Compact Dwarf galaxies in Abell 1689: a photometric study with the ACS},
author = {S. Mieske and L. Infante and N. Benitez and D. Coe and J. P. Blakeslee and K. Zekser and H. Ford and T. J. Broadhurst and G. D. Illingworth and G. F. Hartig and M. Clampin and D. R. Ardila and F. Bartko and R. J. Bouwens and R. A. Brown and C. J. Burrows and E. S. Cheng and N. J. G. Cross and P. D. Feldman and M. Franx and D. A. Golimowski and T. Goto and C. Gronwall and B. Holden and N. Homeier and R. A. Kimble and J. E. Krist and M. P. Lesser and A. R. Martel and F. Menanteau and G. R. Meurer and G. K. Miley and M. Postman and P. Rosati and M. Sirianni and W. B. Sparks and H. D. Tran and Z. I. Tsvetanov and R. L. White and W. Zheng},
journal= {arXiv preprint arXiv:astro-ph/0406613},
year = {2009}
}
备注
29 pages, 10 figures, accepted for publication in the October 2004 issue of the Astronomical Journal