formation of intergroup and intragroup objects kenji bekki (unsw) origin of isolated massive clouds,...

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.