Local Volume TiNy Titans: gaseous dwarf–dwarf interactions in the Local Universe

Abstract

In this paper, we introduce the Local Volume TiNy Titans sample (LV-TNT), which is a part of a larger body of work on interacting dwarf galaxies: TNT (Stierwalt et al. 2015). This LV-TNT sample consists of 10 dwarf galaxy pairs in the Local Universe (< 30 Mpc from Milky Way), which span mass ratios of M * ,1 /M * ,2 < 20, projected separations < 100 kpc, and pair member masses of log(M * /M ) < 9.9. All 10 LV-TNT pairs have resolved synthesis maps of their neutral hydrogen, are located in a range of environments and captured at various interaction stages. This enables us to do a comparative study of the diffuse gas in dwarf-dwarf interactions and disentangle the gas lost due to interactions with halos of massive galaxies, from the gas lost due to mutual interaction between the dwarfs. We find that the neutral gas is extended in the interacting pairs when compared to non-paired analogs, indicating that gas is tidally pre-processed. Additionally, we find that the environment can shape the HI distributions in the form of trailing tails and that the gas is not unbound and lost to the surroundings unless the dwarf pair is residing near a massive galaxy. We conclude that a nearby, massive host galaxy is what ultimately prevents the gas from being reaccreted. Dwarf-dwarf interactions thus represent an important part of the baryon cycle of low mass galaxies, enabling the "parking" of gas at large distances to serve as a continual gas supply channel until accretion by a more massive host.

Lyα Absorbers and the Coma Cluster

“…Another example of the non-detection of Lyα absorption in close proximity to HI emission is the galaxy pair NGC 4532/DDO 137 just beyond R vir and within 2σ v of the Virgo Cluster (Pearson et al 2016). These types of non-detections are interesting in terms of galaxy quenching and are worth further investigation in the future.…”

Under pressure: quenching star formation in low-mass satellite galaxies via stripping

“…However, our analysis suggests that stripping (and specifically rampressure stripping) may require a significantly clumpy host CGM or the assistance of baryonic feedback to effectively remove enough cold gas from the most gas-rich and concentrated systems. Additionally, recent work by Pearson et al (2016) and Marasco et al (2016) shows that the distribution of HI in low-mass field galaxies can be significantly altered via close encounters with neighboring dwarfs. If these encounters occur just before or during infall onto a host system, the resulting satellite's ISM will likely be more susceptible to stripping.…”

Galaxy pairs in the Sloan Digital Sky Survey – XI. A new method for measuring the influence of the closest companion out to wide separations

“…Various approaches to characterizing environment have been used in the literature, including membership and/or location within structures such as clusters, groups, sheets, filaments and voids (Yang et al 2007;Darvish et al 2014;Eardley et al 2015), central/satellite classification (Kravtsov et al 2004), local number density (Cooper et al 2005;Baldry et al 2006), clustering statistics (Robaina et al 2009;Skibba et al 2013), proximity to the nearest massive galaxy (Geha et al 2012;Sánchez-Janssen et al 2013;Ruiz, Trujillo, & Mármol-Queraltó 2014;Pearson et al 2016), etc. Given the particular goals of this study, and our desire to consistently classify a large number of galaxies within a flux-limited galaxy redshift survey, we elect to use two distinct metrics to describe each galaxy's environment.…”