An LBT view of the co-rotating group of galaxies around NGC 2750: Deep imaging and new satellite candidates

TL;DR

This study uses deep imaging to identify new satellite candidates around NGC 2750, revealing a potentially co-rotating satellite group with tidal features, challenging current cosmological models.

Contribution

First deep imaging survey around NGC 2750 identifying new satellite candidates and tidal features, providing evidence for a co-rotating satellite group.

Findings

Six new candidate dwarf galaxies discovered

Tidal features indicating past interactions

Satellite distribution suggests moderate flattening

Abstract

Some galaxies such as the Milky Way and Andromeda display coherently rotating satellite planes, posing tensions with cosmological simulations. NGC 2750 has emerged as an additional candidate system hosting a co-rotating group of galaxies. We aim to assess the presence of a coherent satellite plane around NGC 2750 by identifying new candidate dwarf galaxies and low surface brightness features. We conducted deep, wide-field photometric observations of NGC 2750 using the Large Binocular Telescope in the g- and r-bands. Standard data reduction techniques were applied to enhance the detection of low-surface-brightness features down to about 31 mag/arcsec^2 in r. Our observations led to the discovery of six new candidate dwarf galaxies, including one with properties consistent with an ultra-diffuse galaxy. We also identified tidal features around NGC 2750, indicating past interactions with nearby satellites. The spatial distribution of satellites suggests a moderate flattening, further supported by the newly identified candidates. Follow-up spectroscopic measurements will be critical in confirming or challenging the strong kinematic coherence observed previously. The luminosity function of NGC 2750 reveals an excess of bright satellites compared to similar systems, adding to the growing tension between observed satellite populations and cosmological simulations.