Drivers of asymmetry in synthetic H I emission-line profiles of galaxies in the EAGLE simulation

Abstract

We study the shapes of spatially integrated H emission line profiles of galaxies in the simulation using three separate measures of the profile's asymmetry. We show that the subset of galaxies whose gas fractions and stellar masses are consistent with those in the xGASS survey also have similar H line asymmetries. Central galaxies with symmetric H line profiles typically correspond to rotationally supported H and stellar disks, but those with asymmetric line profiles may or may not correspond to dispersion-dominated systems. Galaxies with symmetric H emission lines are, on average, more gas rich than those with asymmetric lines, and also exhibit systematic differences in their specific star formation rates, suggesting that turbulence generated by stellar or AGN feedback may be one factor contributing to H line asymmetry. The line asymmetry also correlates strongly with the dynamical state of a galaxy's host dark matter halo: older, more relaxed haloes host more-symmetric galaxies than those hosted by unrelaxed ones. At fixed halo mass, asymmetric centrals tend to be surrounded by a larger number of massive subhaloes than their symmetric counterparts, and also experience higher rates of gas accretion and outflow. At fixed stellar mass, central galaxies have, on average, more symmetric H emission lines than satellites; for the latter, ram pressure and tidal stripping are significant sources of asymmetry.

ASymba: H i global profile asymmetries in the simba simulation

“…These cuts remove a total of 246 galaxies and we are left with a sample of 4264 profiles. This is broadly comparable to the sample size studied in Manuwal et al (2021) constructed from the EAGLE simulation and roughly 40% of the sample size constructed from IllustrisTNG100 simulation used in Watts et al (2020b).…”

“…Another key finding of Watts et al (2020b) is that asymmetries are not driven solely by environment, but also multiple physical processes. Manuwal et al (2021) examined profile asymmetries in the Esimulation (Crain et al 2015;Schaye et al 2015;McAlpine et al 2016). They used a variety of methods to quantify the asymmetries and found, like Watts et al (2020b), that satellite galaxies tend to be more asymmetric than central galaxies.…”

On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies

“…matics predicted in cosmological simulations (e.g., El-Badry et al 2018;Oman et al 2019;Watts et al 2020;Manuwal et al 2021), the QSO absorption-line measurements we present here offer a complementary, and in some ways simpler, point of comparison for Galactic Fountain model predictions. Such comparisons are crucial to improving our understanding of the cycling of multiphase gas flows through galaxy disks.…”

WALLABY Pre-Pilot Survey: The effects of tidal interaction on radial distribution of color in galaxies of the Eridanus supergroup

“…The weak relation between line asymmetry and environment has been noticed before (Espada et al 2011;Scott et al 2014;). Although there have been supportive results based on observed and simulated data on the link between enhanced Hi line asymmetry, gas loss and environment density (Watts et al 2020a;Manuwal et al 2021), a direct causality by galactic tidal interaction has not been clearly established.…”