An Extensive Catalog of Early-type Dwarf Galaxies in the Local Universe: Morphology and Environment

Abstract

We present an extensive catalog of 5405 early-type dwarf (dE) galaxies located in the various environments, i.e., clusters, groups, and fields, of the local universe (z < 0.01). The dEs are selected through visual inspection of the Legacy survey’s g–r–z combined tricolor images. The inspected area, covering a total sky area of 7643 deg2, encompasses two local clusters (Virgo and Fornax), 265 groups, and the regions around 586 field galaxies of M K < −21 mag. The catalog aims to be one of the most extensive and publicly accessible collections of data on dEs, despite its complex completeness limits, which may not accurately represent its statistical completeness. The strength of the catalog lies in the morphological characteristics, including nucleated, tidal, and ultradiffuse dEs. The two clusters contribute nearly half (2437 out of 5405) of the dEs, and the 265 groups contribute 2103 dEs. There are 864 dEs in 586 fields, i.e., ∼1.47 dEs per field. Using a standard definition commonly used in literature, we identify 100 ultradiffuse galaxies (UDGs), which compose ∼2% of the dE population. We find that 40% of our sample dEs harbor a central nucleus, and among the UDG population, a majority (79%) are nonnucleated. About 1.3% of dEs suffer from ongoing tidal disturbance by nearby massive galaxies, and only 0.03% show a sign of recent dwarf–dwarf mergers. The association between dEs and their nearest bright neighbor galaxies suggests that dEs are more likely created where their neighbors are non-star-forming ones.

Stellar Population Properties in the Stellar Streams around SPRC047

“…We obtained preprocessed CFHT images that had undergone bias subtraction, flat-fielding, and flux calibration by the MegaCam pipeline system, ELIXIR. To further remove the sky background, we followed a method described in Paudel et al (2023), in which we generated a background map by masking out identified sources in the image using Source Extractor (Bertin & Arnouts 1996) maps. The segmentation images were then filled with median values from surrounding pixels to eliminate light contributions from stars and background galaxies.…”

“…We found an ideal target to test SED fitting in the ultralow surface brightness regime in Canada-France-Hawaii Telescope (CFHT) images as a side product of a search for nearby interacting dwarf galaxies (Paudel et al 2023) in the Sloan Digital Sky Survey and Legacy Surveys (Dey et al 2019). This is a rare ringlike tidal stellar stream (originally cataloged and classified as a polar ring galaxy by Moiseev et al 2011) around the edge-on galaxy SPRC047 (R.A. = 13 h 59 m 41 s , decl.…”

Rejuvenating Star Formation Activity in an Early-type Dwarf Galaxy, LEDA 1915372, with Accreted H i Gas

“…We also performed surface photometry on the optical images of LEDA 1915372. We utilized the legacy r-band images and subtracted the sky backgrounds using the same method described in Paudel et al (2023). To extract the galaxy's major-axis light profile, we employed the IRAF ellipse task, following the manual masking of any non-related background and foreground objects.…”