The J Group: Evolution and Interaction Virginia Kilborn Swinburne University of Technology Sarah Sweet (Australian National University) Gerhardt Meurer (University of Western Australia) Michael Drinkwater (University of Queensland Kenji Bekki (University of Western Australia)

Groups: Galaxy pre-processing Grus quartet: Lutz et al. in prep. Kern et al 2008 Loose groups – 2-4 spiral members + dwarf galaxies Group masses up to approx M  HI-rich

SINGG Choirs Survey for Ionisation in Gas-rich Galaxies (Meurer et al. 2006) SINGG imaged approx 400 galaxies in Hα, selected from the HIPASS HI catalogue (approx 15’ resolution) 15 imaging fields contained 4 or more galaxies: dubbed the SINGG “Choirs” (Sweet et al. 2013) Hα imaging of 3 SINGG groups (orange), overlaid on optical R-band (blue/white) 50kpc

HI Mass distribution of SINGG and the Choirs HI mass from HIPASS

SINGG Choirs: Tidal Dwarf Galaxy laboratories? Horellou & Koribalski 2007 TDGs – important to know how dwarf galaxies are formed for comparison with cosmological simulations

SINGG Choirs: Tidal Dwarf Galaxy laboratories? Recent galaxy interactions- but dwarfs not situated in optically detected tidal tails Measure metalicity and dynamics to determine properties of TDG candidates in the Choirs

Metalicity of TDG candidates Sweet et al Simulations by Bekki et al (in prep) show that TDGs should have moderate metalicity, and faint

Dynamics and mass: Optical data WiFES and Keck spectra of dwarf galaxies – rotation curves to determine total mass Keck Deimos spectrum Sweet et al (in prep)

Dynamics and mass: HI data ATCA and VLA data for all 15 groups

SINGG Choir J SINGG Hα imaging 9 emission line galaxies found in the group

Keck spectra: 5 more dwarf galaxies in group

J : HI imaging S1: HI mass = 4x10 10 M  HI excess (HI def = -0.6) S2 (NGC 3431): HI mass =1.4x10 9 M  HI deficient (HI def = 0.9)

Galaxy properties: TDGs ? Red stars: J group members

Central galaxy: Polar ring? DecCam imaging

S1: UV imaging

Optical dynamics: 2 components

HI dynamics Kilborn et al. 2014, in prep

Ongoing HI accretion?

Summary SINGG Choirs are excellent laboratories to study the physical processes in evolving groups J is a polar ring galaxy with possible ongoing HI accretion Implications for gas fuelling scenarios and TDG formation 14 more Choirs to analyse…

Star formation?

Evolution in galaxy groups Log Lx F early Log  v The early-type fraction Increases with increasing X-ray luminosity and Velocity dispersion More evolved groups: -more early type galaxies -higher velocity dispersions -higher X-ray luminosity