The Leo-I group: new dwarf galaxy and UDG candidates

TL;DR

This paper identifies 36 new dwarf galaxy candidates, including ultra diffuse galaxy candidates, in the Leo-I group, revealing a richer dwarf galaxy population than previously known and providing insights into small-scale structure formation.

Contribution

The study introduces a new sample of dwarf galaxy candidates in the Leo-I group using image enhancement and surface photometry, expanding the known galaxy population in this region.

Findings

36 new dwarf galaxy candidates identified

Leo-I group has twice as many dwarfs as the Local Group at similar magnitude

Presence of ultra diffuse galaxy candidates near the group

Abstract

The study of dwarf galaxies and their environments provides crucial testbeds for predictions of cosmological models and insights on the structure formation on small cosmological scales. In recent years, many problems on the scale of groups of galaxies challenged the current standard model of cosmology. We aim to increase the sample of known galaxies in the Leo-I group, containing the M\,96 subgroup and the Leo Triplet. This galaxy aggregate is located at the edge of the Local Volume at a mean distance of 10.7 Mpc. We employ image enhancing techniques to search for low-surface brightness objects in publicly available gr images taken by the Sloan Digital Sky Survey within 500 square degrees around the Leo-I group. Once detected, we perform surface photometry and compare their structural parameters to other known dwarf galaxies in the nearby universe. We found 36 new dwarf galaxy candidates within the search area. Their morphology and structural parameters resemble known dwarfs in other groups. Among the candidates 5 to 6 galaxies are considered as ultra diffuse galaxies candidates. If confirmed, they would be some of the closest examples of this galaxy type. We assessed the luminosity function of the Leo-I group and find it to be considerably rich in dwarf galaxies, with twice the number of galaxies as the Local Group at a limiting magnitude of M_V=-10 and a steeper faint-end slope.