Dwarf Galaxy Discoveries from the KMTNet Supernova Program. I. the NGC 2784 Galaxy Group

Hong Soo Park, Dae Sik Moon, Dennis F Zaritsky, Mina Pak, Jae Joon Lee, Sang Chul Kim, Dong Jin Kim, Sang Mok Cha

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

We present BVI surface photometry of 31 dwarf galaxy candidates discovered in a deep image stack from the KMTNet Supernova Program of ∼30 square degrees centered on the nearby NGC 2784 galaxy group. Our final images have a 3σ surface brightness detection limit of μv ≈ 28.5 mag arcsec-2. The faintest central surface brightness that we measure is μ0.v = 26.1 mag arcsec-2. If these candidates are at the distance of NGC 2784, then they have absolute magnitudes greater than Mv =-9.5 mag and effective radii larger than 170 pc. Their radial number density decreases exponentially with distance from the center of NGC 2784 until it flattens beyond a radius of 0.5 Mpc. We interpret the baseline density level to represent the background contamination and estimate that 22 of the 31 new candidates are dwarf members of the group. The candidate's average color,<(B-V)0> ≈ 0.7, and Sérsic structural parameters are consistent with those parameters for the dwarf populations of other groups. We find that the central population of dwarfs is redder and brighter than the rest of the population. The measured faint-end slope of the luminosity function, α ≈ -1.33, is steeper than that of the Local Group, but consistent with published results for other groups. Such comparisons are complicated by systematic differences among different studies, but will be simpler when the KMTNet survey, which will provide homogenous data for 15-20 groups, is completed.

Original languageEnglish (US)
Article number19
JournalAstrophysical Journal
Volume848
Issue number1
DOIs
StatePublished - Oct 10 2017

Keywords

  • galaxies: dwarf
  • galaxies: individual (NGC 2784)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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