The Origin of Faint Tidal Features around Galaxies in the RESOLVE Survey

Abstract

We study tidal features around galaxies in the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. Our sample consists of 1048 RESOLVE galaxies that overlap with the DECam Legacy Survey, which reaches an r-band 3σ depth of ∼27.9 mag arcsec −2 for a 100 arcsec 2 feature. Images were masked, smoothed, and inspected for tidal features such as streams, shells, or tails/arms. We find tidal features in 17 ±2 % of our galaxies, setting a lower limit on the true frequency. The frequency of tidal features in the gas-poor (gas-to-stellar mass ratio <0.1) subsample is lower than in the gas-rich subsample (13 ±3 % versus 19 ±2 %). Within the gas-poor subsample, galaxies with tidal features have higher stellar and halo masses, ∼3× closer distances to nearest neighbors (in the same group), and possibly fewer group members at fixed halo mass than galaxies without tidal features, but similar specific star formation rates. These results suggest tidal features in gas-poor galaxies are typically streams/shells from dry mergers or satellite disruption. In contrast, the presence of tidal features around gas-rich galaxies does not correlate with stellar or halo mass, suggesting these tidal features are often tails/arms from resonant interactions. Similar to tidal features in gas-poor galaxies, tidal features in gas-rich galaxies imply 1.7× closer nearest neighbors in the same group; however, they are associated with diskier morphologies, higher star formation rates, and higher gas content. In addition to interactions with known neighbors, we suggest that tidal features in gas-rich galaxies may arise from accretion of cosmic gas and/or gas-rich satellites below the survey limit.

Star Formation in Isolated Dwarf Galaxies Hosting Tidal Debris: Extending the Dwarf–Dwarf Merger Sequence

“…In particular, we note that there exists a significant population of dwarf galaxies that host stellar shells, similar to those observed in higher mass galaxies (Atkinson et al 2013;Carlsten et al 2017;Hood et al 2018;Kado-Fong et al 2018). Such shells have also been observed around early-type dwarf galaxies in the Virgo Cluster (Paudel et al 2017).…”

Overview of the DESI Legacy Imaging Surveys

“…The large time baseline between the Legacy Surveys and SDSS also enables the detection of faint transients and the measurement of proper motions for faint stars (Figure 18 shows an example). The sensitivity of the Legacy Surveys data to low surface brightness structures has been exploited in the new version of Galaxy Zoo (https://blog.galaxyzoo.org/tag/decals/) and for finding faint tidal features associated with galaxies (e.g., Hood et al 2018). In addition, the depth of the Legacy Surveys data has resulted in their use for selecting emission-line galaxy (DECaLS component; Raichoor et al 2017) and QSO targets (WISE component Myers et al 2015) for the SDSS-IV/eBOSS spectroscopic survey.…”

Linking compact dwarf starburst galaxies in the RESOLVE survey to downsized blue nuggets

“…Group halo masses are assigned using halo abundance matching on the group-integrated r -band luminosity as described in Berlind et al (2006) and Eckert et al (2017). Nearest neighbor distances are determined using the kd-tree algorithm of Maneewongvatana & Mount (1999), "correcting" for peculiar velocities as described in Hood et al (2018) by using the group catalog to suppress apparent lineof-sight distances within, but not between, groups.…”