Formation of intergroup and intragroup objects Kenji Bekki (UNSW) Origin of isolated massive clouds, intergalactic HII regions, intragroup GCs etc….

Today’s topic Formation of intragroup HI gas, rings, and HII regions (Bekki, Koribalski, Kilborn, Ryan-Weber, Ryder, Couch, etc…). Evolution of compact group of galaxies (my old studies). Formation of intergroup and intragroup GCs (with Yahagi).

Formation of intracluster/intercluster (group) GCs. (Yahagi & Bekki 2005) The large-scale structure of MPCs (MPC=Metal-poor globular cluster)

Evolution of extended gas disks in high M/L galaxies. NGC 2915 (Meurer et al. 1996) gas stars R HI /R OPT ~ 2.0 gas

Three roles of galaxy interaction and galaxy- group interaction Morphological transformation (e.g., Sp  SB) Triggering starbursts and AGNs (+ GC formation). Formation of intragroup stellar and gaseous (e.g., isolated HI gas, drifting GCs).

Origin of intragroup HI (e.g., recent HIPASS results) (1) Intergalactic rings.(2)IntragroupHI (NGC 2442) Ryan-Weber et al. (2002) Ryder et al. (2002)

Dynamical fate of stripped gas in groups Formation of isolated HI gas around NGC 2442 (Bekki, Koribalski, Ryder, & Couch 2005) ``Dark galaxy formation’’ (Bekki, Kilborn, & Koribalski 2005). Intragroup HII regions from tidal compression of HI clouds (Bekki & Ryan-Weber 2005).

Formation of intragroup HI rings (Bekki et al. 2004) GasStars

HI ring formation from a LSB

(A) Simulation. (B) Observation

Dependence of HI morphology on detection limit cm -2 4*10 18 cm -2 2*10 19 cm -2  N(HI) thres =

``Dark HI galaxy’’ in the Virgo cluster (Minchin et al. 2005)

``Dark HI galaxy’’ as tidal derbis (Bekki et al. 2005)

2D velocity fields of simulated ``dark HI clouds’’. Isolated disk

Intragroup HII regions around NGC 1533 in the Dorado group (Ryan-Weber et al. 2004)

NGC 1533 center HI disk Formation of intragroup HII region from tidal compression.  thres = 3 M solar /pc 2

Gas New stars Formation of Stars within Stripped HI (Bekki et al. 2005)

Other objects: NGC 1490 (Oosterloo et al. 2004) Gemini GMOS observations by de Oliveira et al. (2004)

Evolution of compact groups into field Es (Barnes 1989)

MRC (Meta-rich GC) MPC(Metal-poor GC)

How can we prove figure rotation of Es from GC kinematics ?

Multiple starbursts in multiple mergers (Bekki 2001)

Formation of starburst/AGN in collapasing CGs ? HST morphologies of ULIRGs.

Tidal stripping and common (metal-poor) gaseous halos Outer disk Inner disk

Transformation from spiral-rich groups with no intragroup gas into E-dominated ones with intragroup HI (also with spiral companion). Possible candidate of HI ?

``Selective stripping’’ of outer parts of galaxies in CGs. Formation of common HI envelopes in CGs ? Formation of metal-poor stellar halos (or hot metal-poor X-ray gas) after E formation ? A new clue of ``E+A’’s environments (2dF, 6dF, SDSS etc….e.g., the origin of E+As with companion galaxies)

Formation of intergroup GCs. (Yahagi & Bekki 2005) The large-scale structure of MPCs (MPC=Metal-poor globular cluster)

(Yahagi & Bekki 2005: Bekki & Yahagi 2005) INGC: Intergroup (intercluster, intergalaxy) GCs that are not within any virialized halos. INGC HGC HGC: GCs that are within virialized halos.

Distance (mass) of the closest neighbor halos. R nei M nei

Predictions of INGC properties. (1)~ 100 INGCs / Mpc 3. (2)More metal-poor, slightly younger than those HGC (i.e.., GCs within halos). (3)Immune from GC destruction by galaxy-scale tidal fields: Do they retain fossil information on initial cluster MF ?

Conclusions. (1)Stripped HI as intragroup HI objects (e.g. isolated clouds, rings, ``dark galaxy’’ etc). (2)Metal-poor stellar/gaseous halo formation after transformation from CGs to Es. (3)Formation of intergroup/intercluster GCs in the hierarchical clustering scenario.

Formation of young star clusters (super star clusters) in interaction/merging galaxies. (SSC: M v <-10, size <15pc)

Basic components of a galaxy Globular clusters (GC) Dark matter halo Bulge Disk (thin + thick) Stellar halo

Conclusions. (1)Stripped HI as intragroup HI objects (e.g. isolated clouds, rings, ``dark galaxy’’ etc). (2)Metal-poor stellar/gaseous halo formation after transformation from CGs to Es. (3)Formation of intergroup/intercluster GCs in the hierarchical clustering scenario.