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Formation of intergroup and intragroup objects. Origin of isolated massive clouds, intergalactic HII regions, intragroup GCs etc…. Kenji Bekki (UNSW). Today’s topic. Formation of intragroup HI gas, rings, and HII regions (Bekki, Koribalski, Kilborn, Ryan-Weber, Ryder, Couch, etc…).
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Formation of intergroup and intragroup objects Origin of isolated massive clouds, intergalactic HII regions, intragroup GCs etc…. Kenji Bekki (UNSW)
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. gas stars gas RHI/ROPT~ 2.0 NGC 2915 (Meurer et al. 1996)
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) Ryder et al. (2002) Ryan-Weber 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
(B) Observation (A) Simulation.
Dependence of HI morphology on detection limit N(HI)thres = 1017 cm-2 4*1018 cm-2 2*1019 cm-2
``Dark HI galaxy’’ in the Virgo cluster (Minchin et al. 2005)
Isolated disk 2D velocity fields of simulated ``dark HI clouds’’.
Intragroup HII regions around NGC 1533 in the Dorado group (Ryan-Weber et al. 2004)
Formation of intragroup HII region from tidal compression. HI disk NGC 1533 center rthres = 3 Msolar/pc2
New stars Formation of Stars within Stripped HI (Bekki et al. 2005) Gas
Other objects: NGC 1490 (Oosterloo et al. 2004) Gemini GMOS observations by de Oliveira et al. (2004)
MRC (Meta-rich GC) MPC(Metal-poor GC)
Formation of starburst/AGN in collapasing CGs ? HST morphologies of ULIRGs.
Outer disk Inner disk Tidal stripping and common (metal-poor) gaseous halos
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)
INGC INGC: Intergroup (intercluster, intergalaxy) GCs that are not within any virialized halos. (Yahagi & Bekki 2005:Bekki & Yahagi 2005) HGC HGC: GCs that are within virialized halos.
Predictions of INGC properties. • ~ 100 INGCs / Mpc3. • More metal-poor, slightly younger than those HGC (i.e.., GCs within halos). • Immune from GC destruction by galaxy-scale tidal fields: Do they retain fossil information on initial cluster MF ?
Conclusions. • Stripped HI as intragroup HI objects (e.g. isolated clouds, rings, ``dark galaxy’’ etc). • Metal-poor stellar/gaseous halo formation after transformation from CGs to Es. • 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 Dark matter halo Globular clusters (GC) 1012 108 Bulge 109 Stellar halo 109 Disk (thin + thick) 1011
Conclusions. • Stripped HI as intragroup HI objects (e.g. isolated clouds, rings, ``dark galaxy’’ etc). • Metal-poor stellar/gaseous halo formation after transformation from CGs to Es. • Formation of intergroup/intercluster GCs in the hierarchical clustering scenario.