Constraints on Secular Evolution from Star Clusters in Spirals and Lenticulars

1
Constraints on Secular Evolution from Star
Clusters in Spirals and Lenticulars
Jean P. Brodie UCO/Lick ObservatoryUniversity of
California Santa Cruz
Study of Astrophysics of Globular clustersin
Extragalactic Systems
P. Barmby (CfA), M. Beasley (UCSC), K. Bekki
(UNSW), J. Cenarro (UCSC/U Madrid), L. Chomiuk
(UCSC), D. Forbes (Swinburne), J. Huchra (CfA),
S. Larsen (ESO), M. Pierce (Swinburne), R.
Peterson (UCSC), R. Proctor (Swinburne), J.
Howell (UCSC), L. Spitler (UCSC), J. Strader
(UCSC)
2
Overview

• Galaxy Formation
• Background Globular clusters and their relevance
  to galaxy formation
• Global properties of GC systems in early and
  late-type galaxies
• Bimodal color distributions and implications for
  GC/galaxy formation
• Constraints on secular evolution from GC ages,
  metallicities, specific frequencies and
  correlations with host galaxy properties
• Lenticular Galaxies
• Faint Fuzzies discovery and characteristics
• Ideas on formation
• Signposts for secular evolution?

3
What are Globular Clusters?
M 13

• SSPs single ageand metallicity
• 105 106 Msun
• All galaxies MV lt15 have at least one GC
• 150 in MW400 in M31gt 10,000 in some
  ellipticals
• SN?NGC ? 100.4(Mv15), 2 3 ? greater in Es

4
Associated with galaxies of all
morphological types Constrain theories of
galaxy formation and evolution When and
how? Differences
Constraining galaxy formation

5
Good tracers of star formation histories of
galaxies

• Massive star clusters form during all major star
  formation events
  (Schweizer 2001)
• of young clusters scales with amount of gas
  involved in interaction
  (Kissler-Patig et al 1998)
• Cluster formation efficiency depends on SFR in
  spirals (Larsen Richtler 2000)

NGC 6946 Larsen et al 2001
6
Bimodal Color Distributions
Bimodal color distributions ?globular cluster
sub-populations
Color differences are due to age differences
and /ormetallicity differences
? Multiple epochs and/or mechanismsof formation
V-I 0.95 1.15
Fe/H -1.5 -0.5
7
GC/Galaxy Formation Models

• 1. Formation of ellipticals/GCs in mergers
  (Schweizer 1987, Ashman Zepf
  1992)
• 2. In situ/multi-phase collapse (Forbes,
  Brodie Grillmair 1997)
• 3. Accretion/stripping
  (Cote et al. 1998)
• 4. Hierarchical merging
  (Beasley et al. 2002)2 4 require (temporary)
  truncation of GC formation at high redshift

z
8
Model Predictions

• Key properties Ages, metallicities,
  abundance ratios, kinematics, luminosity
  functions of red and blue sub-pops
• ? Merger model ? old population (age of
  universe less 1 Gyr)
  young population with age of merger
• ? Multi-phase ? 2 old populations one
  slightly (24 Gyr)collapse
  younger than other
• ? Accretion ? blue and red clusters about
  the same age
• ? Hierarchical ? age substructure in red
  sub-pop merging red globulars in
  low-luminosity
  field/group ellipticals 2 Gyr younger
  than in bright cluster
  ellipticals

9
GC Ages

• Increasing evidence that both red and blue
  globular clusters are very old (gt10 Gyr)
• Small percentage of red globular clusters may be
  young
• Ellipticals/Lenticulars NGC 1399
  (Kissler-Patig, Brodie, Schroder et al. 1998
  Forbes et al 2001)
  M87 (Cohen, Blakeslee Ryzhov
  1998) NGC 4472 (Puzia et al 1998
  Beasley et al. 2000) NGC 1023
  (Larsen Brodie 2002) NGC 524
  (Beasley et al 2003) NGC 3610
  (Strader, Brodie et al 2003, 2004)
  NGC 4365 (Larsen, Brodie et al 2003)
  NGC 1052 (Pierce et al 2004) NGC
  7457 (Chomiuk, Strader Brodie 2004)
• PhD theses of T. Puzia and
  M. Hempel
• Spirals M 31 (Barmby et al. 2000 Beasley,
  Brodie et al 2004) M 81 (Schroder,
  Brodie, Huchra et al. 2001)
  M 104 (Larsen, Brodie, Beasley et al
  2002)

10
Constraint 1

• Old ages of both sub-populations
• Inconsistent with major merger picture
• Relevance to Secular Evolution? Read on!

11
Color-Magnitude Diagrams

• Average blue peak color (VI)o0.95 ?0.02
• Average red peak color (VI)o1.18 ?0.04Fe/H
  1.4, 0.6
• (Kissler-Patig, Brodie, Schroder et al. 1998
  AJ)

12
Milky Way

• Peaks at
• Fe/H 1.5 and 0.6
• (Zinn 1985)
• MW GCs are all old

13
Sombrero

• Peaks at (VI)00.96 and 1.21
  Larsen, Forbes Brodie (MNRAS 2001)

Follow-up spectroscopy at Keck indicates vast
majority of GCs (both red and blue) are old (13
Gyr)
Larsen, Brodie, Forbes (2002)
14
GCs and Galaxy Assembly

• Colors of both reds and blues correlate with
  galaxy mass (MV and ?) and colorBlue relation
  difficult to explain under accretion/major merger
  scenarios Constraints on Hierarchical Merging
  Paradigm from ages of GCs in dwarfs (12 Gyr)

Brodie 2001 Larsen, Brodie et al 2001 Strader,
Brodie Forbes 2004
15
Work in progress..

• Even more highly significant with asproxy for
  mass!

V-I
? (km/s)
16
Spirals fit the trend
Red GC relation has same slope as galaxy color
relation ? Red GCs and galaxy stars formed in
the same star formation event
Metal-rich GCs in spirals and ellipticals have
the same origin they formed along with the
bulge stars
.
Brodie Huchra 1991 Forbes, Brodie Grillmair
1997 Forbes, Larsen Brodie 2001 Larsen,
Brodie, Huchra et al 2001
17
Constraints 2

• Similarities between peak colors in spirals and
  ellipticals
• Hints at universal GC formation processes
• Slope of red GC color vs galaxy mass relation is
  same as galaxy color vs galaxy mass relation
  (true for spirals and ellipticals)
• Red GC formation is linked to formation of
  bulge

18
Bulge GCs
Number of metal-rich GCs scales with the bulge
Forbes, Brodie Larsen ApJL (2001)
19
Numbers/Specific Frequency
? Metal-rich GCs in spirals are associated
with bulge not disk? bulge (red/MR) GCs scales
with bulge luminosity ? red GCs/unit bulge
light bulge SN 1 ? The total SN for field
ellipticals is 1?3 (Harris 1991)
? The fraction of red GCs in ellipticals is about
0.5 ? The bulge SN for field ellipticals is 1
? Spirals and field ellipticals have a similar
number of metal-rich GCs per unit (bulge)
starlight
20
Specific Frequency

• SN (total) constant at 0.55 for spirals with
  B/T0.3 (Sb and later)
• Constant number of GCs formed in late-type
  spirals
• Universal old halo population
• SN (total) 2 for field Es
• If higher SN for Es due to extra GCs formed
  with bulge, expect SN to scale with B/T from
  0.550.25 at B/T0 to 1.90.5 at B/T1

?3957
2.0
SN

1.0


0.5
M51


0.8
0.2
B/T
Goudfrooij et al 2003
Chandar et al 2004
21
Exceptions ? Secular Evolution?

• NGC 3628 InteractingHI tidal plume bridge
  connection with NGC 3627 extra GCs formed in
  interaction?
• NGC 7814 Best evidence? Least luminous sample
  galaxy (5 x less than NGC 4594).
  Satellite-to-main galaxy mass ratios of 10 more
  common for low mass galaxies
  (Goudfrooij et al 2003)
• M 51 Does it have a bulge?Interacting with NGC
  5195Too few bulge (MR) GCs? (uncertain
  estimate)16 vs 98 (bulge/disk deconvolution) or
  16 vs 45 (? BH mass) (Chandar et al
  2004)

22
Constraints 3

• Number of metal-rich GCs scales with the bulge
  luminosity
• Specific frequency as function of B/T broadly
  consistent with universal halo (blue) GC
  population extra (red) GC population formed
  with bulge

23
Conclusions

• 1) Number of metal-rich GCs scales with the
  bulge luminosity
• 2) Chemical evidence also suggests that
  metal-rich GC formation closely linked to bulge
  formation
• 3) Metal-rich GCs are old
• 1),2) 3) argue against secular evolution
• However, exceptions allow for bulge build-up by
  secular evolution ?
• Galaxies of similar morphological type can have
  different formation histories

24
Lenticular Galaxies
Faint Fuzzies CollaboratorsAndi Burkert, Soeren
Larsen

• HST program to study GCs in NGC 1023 (MB
  20)
• Nearby (10 Mpc) S0 galaxy ?Faint endof GCLF

Brodie Larsen 2002 Larsen Brodie 2000
25
NGC 1023 GCLF

• Faint wing of NGC 1023 GCLF deviates
  significantly from Milky Way GCLF
• 3rd population of clusters in addition to normal
  compact red and blue GC sub-populations

26
GC Selection

• Typical GC Reff 23 pc
• 29 objects in NGC 1023 with Reffgt7 pc
• Almost all are red

27
Spatial Distribution

• Background cluster of galaxies ruled out
• Extended objects have annular distribution
  corresponding to galaxy isophotes

28
Color-Magnitude Diagram

• Extended red objects fainter than compact red
  clusters
• 23 lt V lt 24

M
29
Search for other Faint Fuzzies

• FFs detectable in 4 galaxies (3S0s, 1E) in HST
  WFPC2 archive
• Found in 2
• N 1023, N 3384
• (both SB0s in groups)
• Ruled out in 2
• N 3115 (S01, isolated),
• N 3379 (E)
• ACS data

30
Keck Spectroscopy
Brodie Larsen AJ 2002

• NGC 1023 masterspectrum ltFe/HgtFF10230.580
  .24
• represents 133 hours of 10-m telescope time
• NGC 3384 - 30 hours
  ltFe/HgtFF33840.640.34

31
Velocities

• NGC 1023 ltVFFgt55964 km/s
• Vgal601 km/s
• NGC 3384 ltVFFgt76879 km/s
• Vgal704 km/s
• FFs are 2 bulge Reff from center ? disk not
  bulge objects

32
Ages

• FFs are mostly likely 13 Gyr old and not
  younger than 78 Gyr
• Stable against disruption

33
New Kind of Cluster?
Globular Clusters
Milky Way
NGC 1023
Open clusters are smaller, younger and less
massiveNo MW objects correspond in metallicity,
luminosity and size
34
New Kind of Cluster?
Open clusters are smaller and less massive
Age gt 1 Gyr
L vs Size
L vs Age
Milky Way Open Clusters
35
Origins

• FFs have no analogs in MW or elsewhere in LG
• Found exclusively in lenticulars (so far)
• Is the mechanism responsible for the formation of
  FFs linked to the mechanism for forming
  lenticulars?

36
Distribution and Kinematics

• Distribution of VFF not same as galaxy rotation
  curve
• FFs located in a ring with radius 1.5 (4-5
  kpc) and Vrot 200 km/s
• Tidal radius 48 pc

37
Extended Cluster Formation

• Simulations of Geyer Burkert (2003, 2004) form
  bound clusters with sizes and masses of FFs in
  GMCs if star formation occurs with a density
  threshold
• Under what circumstances do these special
  star-forming conditions occur?
• 1. Galaxy-galaxy interations? e.g. Cartwheel

11
2. Resonance rings and secular evolution
38
Faint Fuzzies Signposts for secular evolution?

• NGC 1023 and NGC 3384 are barred
• NGC 3115 is not
• ?B 3.5 kpc in NGC 1023 (Debattista et al
  2002)
• Bulge is red (old, MR)
• Kinematically and chemically decoupled nuclear
  disk (stars 7 Gyr)

39
NGC 3081
Buta et al (2004)

• MB?20 early-type (S0/a, Sa) barred spiral
  (bulgeless)
• Inner ring encircles bar at 5 kpc
• 58 blue (young) clusters in ring with MV lt?9
  (Vlt23.6) Typical cluster effective radius 11 pc
  !
• Will these clusters survive?
• Is bar formation important in forming lenticular
  galaxies?

40
Implications

• If FF formation is linked to bar formation in
  disk galaxies
• ?
• Disks and bars were present in galaxies at
  high redshift (z gt2)