The J1051-17 Group: Evolution and InteractionVirginia KilbornSwinburne University of Technology

Sarah Sweet (Australian National University)Gerhardt Meurer (University of Western Australia)Michael Drinkwater (University of QueenslandKenji 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. 1013 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. 2014

Simulations by Bekki et al. 2014 (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 spectrumSweet et al. 2014 (in prep)

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

SINGG Choir J1051-17

SINGG Hα imaging

9 emission line galaxiesfound in the group

Keck spectra: 5 more dwarf galaxies in group

J1051-17: HI imaging

S1: HI mass = 4x1010M

HI excess (HI def = -0.6)

S2 (NGC 3431): HI mass =1.4x109M

HI deficient (HI def = 0.9)

Galaxy properties: TDGs ?

Red stars: J1051-17 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

• J1051-17 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 F ea

rly

Log v

The early-type fractionIncreases with increasing X-ray luminosity and Velocity dispersion

More evolved groups:-more early type galaxies-higher velocity dispersions-higher X-ray luminosity