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Conference Introduction Duncan Forbes Swinburne University.

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Presentation on theme: "Conference Introduction Duncan Forbes Swinburne University."— Presentation transcript:

1 Conference Introduction Duncan Forbes Swinburne University

2 Conference Introduction Thanks to Meghan, Frazer and Mike Preview the upcoming conference (ie Ill give the least accurate talk) Personal and biased view (ie Ill forget to mention your seminal paper on environment) Lets have a clean and open discussion (no plutos)…



5 This conference aims to…disentangle the complex interplay between nature and nurture. Malaysia, March 2009

6 SOC chair: Lourdes Verdes Montenegro

7 Defining Environment Field, Group and Cluster Projected local number density of nearby galaxies (volume density better) Cluster-centric distance (which centric?)

8 Defining Environment Halo, subhalo, satellite Halo mass 3D dark matter density

9 Morphology-Density Relation Dressler 1980 Clusters Field With time, spirals are replaced by S0s - Dressler et al. 1997

10 Morphology-SF-Density Relation for Dwarf galaxies Forbes et al dI -> dE -> dSph Einasto et al Mayer et al. 2006

11 In the extreme… Environmental trends due to: Nature: everything due to initial conditions, eg massive galaxies form early in the highest overdensities. OR Nurture: everything due to environment, eg galaxy-galaxy, galaxy-ICM, galaxy-dark matter interactions.

12 What supresses star formation? Hopkins et al. 2004

13 Environmental Madau plot Crain et al. 2009

14 Gray et al dFGRS (Lewis et al. 2002) and SDSS (Gomez et al. 2003) => pre-processing in Groups ? The low density Field includes some quiescent galaxies (Gray et al. 2004) Supression at (group-like) densities

15 What supresses star formation? Haines et al Observation Lower density, less SF suppressed 100% star forming

16 What supresses star formation? Croton et al Model Haines et al Observation

17 Environmental Processes Steady gas accretion Ram pressure stripping (gas removal) Strangulation (turnoff gas supply) Interactions & Harassment (high ) Mergers (low ) Review by Boselli & Gavazzi 2006

18 Kacprzak et al High redshift gas accretion Stream-fed galaxies Dekel et al. 2009

19 Rasmussen et al Stripping in a Group

20 Sun et al. 2005

21 => Formation of dark-matter free Tidal Dwarf Galaxies ? Interactions and Mergers

22 Globular Cluster tidal stripping/accretion Bekki etal. 2003

23 Peng etal GC/L V

24 Environmental Processes Ram pressure stripping (gas removal) Strangulation (turnoff gas supply) Steady gas accretion Interactions & Harassment (high ) Mergers (low ) Are their timescales and any feedback processes consistent with the observed Red sequence, green valley and blue cloud ?

25 The Dearth of Environment Dependence Van den Bosch et al. 2008


27 M V < -20 High density Low density Redshift Red galaxy fraction Evolution of the red sequence (Bell et al. 2004) Butcher-Oemler effect in place at medium redshift and in the field.

28 Formation vs Assembly De Lucia 2007

29 ~13 Gyrs old dissipative rapid burst NGC1400 M B = -20 E/S0 Spolaor et al % See poster by Foster et al.

30 NGC 4649 Globular Clusters Pierce et al. 2006

31 Cluster-centric predictions Caution: global vs central values Caution: physical vs projected radii Caution: splashback De Lucia 2007

32 No X-ray Halo Stripping in Groups Helsdon et al Isolated BGGs Non-BGGs

33 Luminosity Functions Miles et al Low L X groups Low sigma Lots of spirals Current merging Pre-virialised

34 Isolated Elliptical Galaxies A `control sample unaffected by the group/cluster environment Reda, Forbes et al. (2004) Early-type galaxy, V < 9,000 km/s, B < 14 No neighbours within: 700 km/s 0.67 Mpc in plane of the sky 2 B mags (factor of 6 in mass) => 36 ellipticals


36 Colour-magnitude relation

37 Fundamental Plane Deviant galaxies have young stellar populations and/or disturbed morphology Reda, Forbes & Hau 2005

38 FP – Kappa style

39 Radial Kinematics Hau & Forbes 2005

40 NGC the nearest isolated elliptical galaxy ?

41 Radial Ages - NGC 821 Proctor,Forbes etal. 2005

42 Multi- GC systems Strader et al Both red and blue sub- pops are coeval at ~12 Gyr old. Most GC formation in massive ellipticals happened at z > 2, not in recent mergers. BlueRed Old age isochrones

43 Galaxy Bimodality M V ~ -20, M ~3x10 10 M o, M halo ~6x10 11 M o Luminosity function, Colour-magnitude, Star formation rates, bulge/disk ratio, X-ray emission, stellar age, AGN emission, M/L ratio Globular Cluster Specific Frequency Transition from hot accretion flows to cold accretion plus AGN/SN feedback (see Dekel, Keres, Croton etc)

44 Relative GC numbers versus host galaxy stellar mass GC T N -parameter M * = galaxy stellar mass computed from 2MASS K-band mag Problem: Star formation histories vary Transition at M * ~few x M sun (Forbes 2005)

45 globular clusters are ~0.007% of a halos mass Galaxy Halo Mass Globular Cluster System Mass

46 globular clusters are ~0.007% of a halos mass Galaxy Halo Mass Globular Cluster System Mass MW & M31 halo masses from Xue et al & Lee et al. 2008

47 Galaxy Halo Mass Globular Cluster System Mass Spitler & Forbes 2009 No clear environment trend

48 Globular Clusters in Galaxy Clusters Where are the GCs in the Virgo galaxy cluster? 25% in M87 46% satellites 29% intracluster 100% The GC mass of a cluster-sized halo should include these 3 components. (Bekki et al. 2006)

49 globular clusters are ~0.007% of a halos mass Galaxy Halo Mass Globular Cluster System Mass

50 Galaxy Halo Mass Globular Cluster System Mass globular clusters are ~0.007% of a halos mass

51 Galaxy Halo Mass Globular Cluster System Mass globular clusters are ~0.007% of a halos mass LG total masses from Mateo 1998 Fornax Sag. N147 N185 N205

52 Potential method for determining Halo Masses… GC formation appears to be directly proportional to the host halo mass 0.007% of Halo Mass = (Globular Cluster System Mass)

53 Conclusions Massive isolated galaxies can be quiescent Environment influences greater for dwarfs Galaxy (and GC) properties are bimodal Consider formation vs assembly times Galaxies have (strong) mass trends Some isolated galaxies show signs of a merger Globular clusters provide an alternative probe of galaxy formation and assembly And finally…

54 …Not Nature vs Nurture but Nature AND Nurture Have a great conference…

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