Galaxy Systems in the Optical and Infrared. Andrea Biviano INAF/Oss.Astr.Trieste

Transcription

1 Galaxy Systems in the Optical and Infrared Andrea Biviano INAF/Oss.Astr.Trieste

2 Plan of the lectures: I. Identification, global properties, and scaling relations II. Structure and dynamics III. Properties of the galaxy populations

3 Introduction

4 The most striking characteristics of the cluster galaxy population: its morphology mix

5 Field

6 Cluster

7 Morphology+Luminosity Segregation segregation in projected phase space Velocity Bright E less bright E and S0 (B.+02) Sa Sb Sbc...later Radius

8 Why do the galaxies care about the density of the environment? Analyse the properties of cluster galaxy populations in relation to their environment as a function of redshift mechanisms of galaxy evolution

9 The properties of cluster galaxies: morphologies

10 (Dressler 80) Regular trend of morphology change with density S0 E Fraction S+Irr log(local density)

11 (Postman & Geller 84) Regular trend of morphology change with density Spirals S0 Ellipticals log(local density)

12 Another example of morphology vs. density

13 Regular trend of morphology change with radius (Whitmore+93) Ellipticals S0 S+Irr clustercentric distance

14 Morphology Density Relation (MDR) Morphology Radius Relation (MRR)...but also: Morphology Velocity Relation (MVR) (Sodré+89)

15 Morphology Velocity Relation (MVR) (Adami+98) v E S0 Sa Sb Sbc...later

16 Another example of velocity vs. morphology

17 The MDR at z~1: still there, but less S0, more S (Postman+05)

18 The MRR at z~1: still there, but less S0, more S (Postman+05)

19 Brightest galaxies in two z~1 clusters (Postman+05)

20 fraction MDR not present in medium z irregular clusters log (surface density) (Dressler+ 97)

21 (Desai+07) Most MDR evolution occurs at z<0.5

22 S0 form earlier in higher density regions (Smith+05)

23 Less evolution for more massive galaxies Redshifts: (Holden+07)

24 The properties of cluster galaxies: colors

25 The color magnitude relation, CMR B I color (from Durham Univ. website) I band magnitude

26 CMR also for dwarf galaxies (Hilker+03) V I color V band magnitude

27 CMR also at high z (Kurk+08) z J color z=1.6 confirmed overdensity J band magnitude

28 (Ellis+06) CMR zero point vs. z zf 2

29 CMR zero point vs. z zf 2 Solid: zf=3 (De Lucia+07) Dashed: zf=2

30 CMR vs. R age gradient scatter (Wake+05) zero point

31 CMR vs. local density age gradient (Pimbblet+06)

32 CMR faint end forms at low z z =0.1 Red galaxy luminosity functions for two cluster samples z =0.5 (Stott+07)

33 CMR faint end forms at low z Bright to faint red galaxies number ratio (De Lucia+07) redshift

34 CMR faint end forms at low z...more rapidly in higher M clusters Bright to faint red galaxies number ratio (Gilbank+08) redshift

35 CMR faint end forms at low z...at the expense of blue galaxies (Gilbank+08) LF Red gals

36 CMR faint end forms at low z...at the expense of blue galaxies (Gilbank+08) LF All gals

37 (Butcher & Oemler 84) fraction of blue galaxies Blue galaxies red galaxies with time fb with z... the Butcher Oemler effect redshift

38 felg with z... the spectroscopic B O effect low redshift (Poggianti+ 06) fraction of emission line galaxies high redshift cluster velocity dispersion

39 (Coia+ 05) fir emitters with z... the IR B O effect IR emission contours & optical image

40 fir emitters with z... the IR B O effect (Geach+ 06) LIR SFR SFR per unit mass increases with redshift

41 Cluster galaxy color evolution occurs later for fainter galaxies in the lower density cluster regions for less massive clusters

42 Cluster galaxy morphological evolution occurs later for fainter galaxies in the lower density cluster regions for less massive clusters

43 CMR & MDR: the same phenomenon?

44 CMR & MDR: the same phenomenon? Color age (Wolf+07) No MDR at fixed age CMR more fundamental

45 CMR & MDR: the same phenomenon? CMR more fundamental CMR evolution proceeds faster: evolution of galaxy mass function passive, red cluster spirals early S with = age of S0

46 (Bundy+06) log fraction Galaxy Mass Function becomes dominated by RED galaxies before becoming dominated by EARLY type galaxies log (M)

47 CMR & MDR: the same phenomenon? CMR more fundamental CMR evolution proceeds faster: evolution of galaxy mass function passive, red cluster spirals early S with = age of S0

48 Normal S Passive spectrum, blue disk Passive spectrum red disk (Moran+07)

49 CMR & MDR: the same phenomenon? CMR more fundamental CMR evolution proceeds faster: evolution of galaxy mass function passive, red cluster spirals early S with = age of S0

50 Sa/b and S0 have = age in highest density regions (Wolf+07)

51 The properties of cluster galaxies: masses

52 Early type galaxies lie on a Fundamental Plane ETG FP relates their central v z=0.54 surf. brightness effective radius FP zf 2 (Moran+07) Solid: local relation Star symbols: E Diamonds: S0

53 Deviation from FP expressed as M/L difference Lower M/L for less massive ETG younger age (Moran+07) p Also: field ETG younger than cluster ETG

54 Deviation from FP expressed as M/L difference Lower M/L for less massive ETG younger age Also: Low z cluster High z clusters Field (di Serego+06) field ETG younger than cluster ETG

55 Deviation from FP expressed as M/L difference Lower M/L for less massive ETG younger age Also: cluster S0 younger than cluster E (Barr+06)

56 FP analysis supports conclusions from CMR and MDR analyses

57 The properties of cluster galaxies: luminosities

58 Cluster LF field LF? (Driver+04) Bright knee Dip Steep faint end

59 'knee' magnitude M* Cluster LF field LF? filled circles: group open circles: field slope (Martĺnez+02) morphological type

60 Cluster LF: shallower slope at small radii (Popesso+06)

61 Cluster LF: shallower slope at small radii...a.k.a. luminosity segregation (Pracy+04)

62 (Capelato+80) Luminosity segregation: brighter galaxies closer to R=0 Spatial distributions of bright and faint galaxies

63 Another example of luminosity vs. density

64 velocity Brighter galaxies closer to cluster center but also closer to V cluster (B.+92) magnitude

65 (Adami+98) Velocity dispersion Brighter galaxies closer to cluster center but also closer to V cluster Absolute magnitude Luminosity segregation: Ellipticals, not S0

66 Brightest Cluster Galaxies: sizes > field galaxies with = luminosities

67 BCG intimately related to their cluster Central location Alignenent LBCG Mcluster solid line: BCG dashed line: 2nd brightest (Ramella 07)

68 BCG intimately related to their cluster Central location Alignenent LBCG Mcluster (Lin & Mohr 04)

69 BCG color zf 2...but BCG stellar mass increased since z~1 in low M clusters (Brough+02)

70 BCG in lower M clusters keep growing as their host clusters grow Fraction of total cluster light in the BCG anti correlated with cluster mass (Lin & Mohr 04)

71 Lum(BCG)/Lum(2 brightest) in more regular (more evolved?) clusters nd (Ramella+07) Solid: regular clusters Dashed: clusters with subclusters

72 BCG companions merger expected in ~0.1 Gyr z=0.39 cluster optical surface brightness contours (Rines+07)

73 Intra Cluster Light related to BCG Similar colors Aligned Clusters with brighter BCG also have higher ICL surface brightness ICL light ~ 5 25 % total light

74 Intra Cluster Light related to BCG Similar colors Aligned Clusters with brighter BCG also have higher ICL surface brightness ICL light ~ 5 25 % total light

75 The properties of cluster galaxies: nuclear activity

76 AGN fraction: no (?) dependence on local density (Popesso & B. 06) but strong dependence on v

77 Physical processes

78 Processes capable of affecting cluster (and group) galaxy properties: dynamical friction galaxy galaxy collisions tidal effects & mergers tidal forces induced by cluster d /dr tidal truncation ram pressure stripping Starvation can result from any of the processes as the galaxy gas is expelled or consumed

79 Dynamical friction timescale

80 Galaxy galaxy collision timescale

81 Rapid collisions 'harassment' Morphological evolution (Moore+96)

82 Collisions gas expelled by tidal forces (Durbala+08)

83 Slow collisions mergers Merger timescale Leading to tidal gas loss and morphological evolution (Barnes 92)

84 Galaxy orbiting cluster suffers tidal truncation outside rt: rc 2 rpericenter BCG at r=0 not truncated, symmetric external forces

85 Ram pressure from IC gas strips the galaxy gas from the galaxy halo from the galaxy disk

86 Tidal or ram compression of galactic gas central starburst (Byrd & Valtonen 90)

87 (Moran+07) Different processes are efficient in different environments

88 Evolutionary scenarios

89 'Nature' vs. 'nurture'? Nature: CMR and MDR in place at high z Bright ETG undergo only passive evolution Nurture (?): S0, fainter ETG, ETG in lower density regions are younger, especially in low M irregular clusters Cluster LF field LF (BCG, ICL)

90 Use Ockham's razor: no nurture if nature suffices Hierarchical cosmological models naturally predict biased galaxy formation: more massive galaxies form earlier in denser environment (earlier collapse of density fluctuations) hence they form their stars, run out of fuel, and stop forming stars earlier

91 Use Ockham's razor: no nurture if nature suffices Hierarchical cosmological models naturally predict biased galaxy formation: more massive galaxies form earlier in denser environment (earlier collapse of density fluctuations) hence they form their stars, run out of fuel, and stop forming stars earlier

92 Downsizing

93 Numerical simulations: Galaxy mass (Cen & Ostriker 93) (Gas mass) /(total mass) formation redshift

94 But nurture does play a role in hierarchical models: galaxies grow via mergers Mergers increase galaxy masses destroy disks and spiral arms reduce angular momentum trigger starbursts (reduce gas content) form central Black Holes and AGNs (AGN feedback quench SF) Mergers effective in high density regions with low v (at early times or via dynamical friction)

95 (La Barbera+04) Merger origin of ellipticals: flat metallicity and color gradients

96 (Silverman+08) Merger origin of AGN: host galaxy colors and morphologies 1 4 Gyr old starburst

97 (Popesso & B. 06) Merger origin of AGN: fraction vs. v fitted by merger model

98 Mergers become inefficient at later times in galaxy clusters when v Mergers at later times can still operate in lower v but relatively high density regions, i.e. groups (subclusters) and filaments

99 Mergers become inefficient at later times in galaxy clusters when v Mergers at later times can still operate in lower v but relatively high density regions, i.e. groups (subclusters) and filaments

100 (Fadda+08) Mergers suggested by starburst activity in galaxies of cluster feeding filaments <z>=0.2

101 (De Lucia & Blaizot 07) Dynamical friction merger continues until late in central cluster region BCG continues to grow up

102 Dynamical friction and mergers can explain luminosity segregation (Springel+01)

103 Merger explains bright part of LF cluster vs. field Mass of merger products < (progenitor masses) lost mass during mergers create ICL Faint end LF maybe created from tidal dwarfs (they cannot survive in the central cluster regions)

104 Merger explains bright part of LF cluster vs. field Mass of merger products < (progenitor masses) lost mass during mergers create ICL Faint end LF maybe created from tidal dwarfs (they cannot survive in the central cluster regions)

105 Merger explains bright part of LF cluster vs. field Mass of merger products < (progenitor masses) lost mass during mergers create ICL Faint end LF maybe created from tidal dwarfs (they cannot survive in the central cluster regions)

106 Hierarchical clustering CDM numerical simulation with: cooling, star formation, SN feedback, dynamical friction, mergers MRR ~ OK S0? not really (Springel+01)

107 Producing S0: low luminosity S0 from fading spirals Spiral gas removed via tidal effects, ram pressure A thesis supported by the analyses of: Blue vs. Red LF evolution Specific number of globular clusters

108 Producing S0: low luminosity S0 from fading spirals Spiral gas removed via tidal effects, ram pressure A thesis supported by the analyses of: Blue vs. Red LF evolution Existence of intermediate galaxy class Specific number of globular clusters

109 CMR faint end forms at low z...at the expense of blue galaxies (Gilbank+08) LF Red gals

110 CMR faint end forms at low z...at the expense of blue galaxies (Gilbank+08) LF All gals

111 Producing S0: low luminosity S0 from fading spirals Spiral gas removed via tidal effects, ram pressure A thesis supported by the analyses of: Blue vs. Red LF evolution Existence of an intermediate galaxy class Specific number of globular clusters passive S, HI deficient S

112 Normal S Passive spectrum, blue disk Passive spectrum red disk (Moran+07)

113 (Kenney+04)

114 Producing S0: low luminosity S0 from fading spirals Spiral gas removed via tidal effects, ram pressure A thesis supported by the analyses of: Blue vs. Red LF evolution Existence of an intermediate galaxy class Specific number of globular clusters

115 (Barr+07) When age SN NGC / Lum

116 Producing S0: High luminosity S0, fading spirals insufficient Must increase bulge luminosity Via minor mergers and/or tidally induced central stabursts Possible progenitors: E+A galaxies

117 Producing S0: High luminosity S0, fading spirals insufficient Must increase bulge luminosity Via minor mergers and/or tidally induced central stabursts Possible progenitors: E+A galaxies

118 Spectrum with strong Balmer lines fit by Elliptical like + A stars (post starburst) (Dressler+Gunn 83)

119 Recent creation of bright S0 can occur in low v subclusters Observational evidence for a high fraction of S0 in subclusters (B.+02)

120 Conclusions: We are close to understand the physical meaning of the Hubble tuning fork!

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124 Thank you for the attention!