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)

gasstars

RHI/ROPT~ 2.0

gas

Three roles of galaxy interaction and galaxy-

group interaction

• Morphological transformation (e.g., SpSB)• 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)

Gas Stars

HI ring formation from a LSB

(A) Simulation. (B) Observation

Dependence of HI morphology on detection limit

1017 cm-2 4*1018 cm-2 2*1019 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 HIclouds’’.

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 Msolar/pc2

Gas

New stars Formation ofStars withinStripped 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.

Rnei Mnei

Predictions of INGC properties.

(1) ~ 100 INGCs / Mpc3.(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: Mv<-10, size <15pc)

Basic components of a galaxy

Globular clusters (GC) Dark matter halo

Bulge

Disk (thin + thick)

Stellar halo

108 1012

109

1011

109

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.