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ACS Observations of Distant Clusters of Galaxies & Protoclusters: New Constraints on Cluster and Galaxy Formation & Evolution Marc Postman STScI. Talk Outline. Overview - what we know and don’t know (about cluster & cluster galaxy formation & evolution) Sample definition Results at z ~ 1

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  1. ACS Observations of Distant Clusters of Galaxies & Protoclusters:New Constraints on Cluster and Galaxy Formation & EvolutionMarc PostmanSTScI STScI Colloquium

  2. Talk Outline • Overview - what we know and don’t know (about cluster & cluster galaxy formation & evolution) • Sample definition • Results at z ~ 1 • Constraining the SF history of early type cluster galaxies • Tracking the evolution of cluster galaxy morphologies • Brightest Cluster Galaxy assembly and evolution • Galaxies, x-rays, and gravitational lensing: looking for evidence of cluster assembly • High-z RGs - Tracers of Protocluster sites? • TN1138 - an intriguing system at z = 4.1 - evidence in support of an associated protocluster • Epilogue - an update to the structure formation story STScI Colloquium

  3. Cluster Origins John Blakeslee (JHU) Frank Bartko (Colorado) Nicholas Cross (JHU) Ricardo deMarco (ESO/JHU) Holland Ford (JHU) Marijn Franx (Leiden) Brad Holden (UCSC) Nicole Homeier (JHU) Garth Illingworth (UCSC) Marco Lombardi (ESO) Felipe Manenteau (JHU) Piero Rosati (ESO) Weak Lensing Myoungkook Jee (JHU) Rick White (STScI) Narciso Benitez (JHU) Hi-z Radio Galaxies George Miley (Leiden) Roderik Overzier (Leiden) Andrew Zirm (Leiden) My ACS IDT Collaborators • ACS IDT Archive • D. Golimowski, K. Anderson • T. Allen, W. J. McCann • A. Framarini, G. Meurer STScI Colloquium

  4. Cluster Formation Scenario Simulation by J. Colberg (Starts at z = 20) • Primordial Intra-cluster medium (ICM) shocks at the intersection of matter streams and begins to emit x-rays (epoch?? Probably z > 2). • Since z = 1, there is little or no evolution in the thermodynamics & metallicity of the ICM. • Massive ellipticals assemble in range 2 < z < 5 (How does assembly proceed? Direct observations??); they are the first galaxies to reach dynamic equilibrium with the cluster potential. (Global cluster effects?) • Most cluster galaxy SF activity is quenched by z=0.5 (Dressler et al. 1997). (Trigger?) • Infall of spirals results in morphological and color gradients within the cluster (When are gradients first detectable?). This process continues into the present epoch. • S0 and dE populations develop within the cluster core (epoch?? Timescales?). HSB spirals S0; LSB spiralsdE (Moore et al 1998) (Verify. Find progenitors at high-z??) STScI Colloquium

  5. ACS GTO Cluster Survey • Cluster Galaxy Formation & Evolution • Goals: Study, with best precision to date, the star formation rates, internal structures, & fundamental relationships in cluster galaxies at z ~ 1. Study the origins of the most massive cluster galaxies and their link to possible progenitors. • 8 rich galaxy clusters in the range 0.8 < z < 1.3 • 4 high-z radio galaxies: Protoclusters at 2 < z < 5? • ACS imaging in at least 2 bands, NIR & x-ray imaging, plus extensive optical spectroscopy. STScI Colloquium

  6. ACS GTO Cluster Survey • The ACS Advantage • High sensitivity makes moderately wide coverage in at least 2 passbands affordable for a modest size sample. • Higher angular resolution provides superior constraints on galaxy structure (e.g., morphology, half-light radii) and lensing. • The combination yields superior photometric and morphological data that enables study of mass distributions and galaxy properties in z~1 clusters in unprecedented detail. STScI Colloquium

  7. Cluster Survey Targets STScI Colloquium

  8. CL0152 & MS1054 @ z = 0.83 CL0152 (z=0.837) MS1054 (z=0.831) STScI Colloquium

  9. CL1604+43 @ z ~ 0.91 CL1604+4304 (z=0.897) CL1604+4321 (z=0.924) STScI Colloquium

  10. CL0910 + CL1252 @ z > 1 CL0910+5422 (z=1.101) CL1252-2927 (z=1.235) STScI Colloquium

  11. Constraining the ages of early-type cluster galaxies from the Color-Magnitude Relation • “Red” Sequence in clusters – a galaxy population, largely of early-type morphology, with a relatively narrow range in color but spanning a modest range in luminosity. It is a common feature in most rich clusters to z < 1. • The CM relation is most likely due to an underlying mass-metallicity relation (e.g., Kodama et al. 1997). • Slope of and scatter about the CM relation provide constraints on the formation epoch and star formation history of galaxies. STScI Colloquium

  12. r-i vs i V-i vs i V-I vs I Elliptical S0 Spiral V-I vs I i-z vs z STScI Colloquium

  13. Estimating Epoch of Last Major Star Formation Event zF > 1.6 STScI Colloquium

  14. INT = 0.023±0.007 mag (15 Egal spec-confirmed members) INT = 0.026 mag (31 Egals, sigma-clipped result) INT = 0.029 mag (All 52 Egals with z mag < 24.5) Additional constraints from the observed evolution of scatter about & slope of the CM relation Blakeslee et al. 2003 Coma Cluster @ z =0.02 CL1252 @ z=1.24 STScI Colloquium

  15. Modeling the scatter Model 1: Galaxies form stars in single bursts at random times between t0 (z~1000) and tEND (z > 1.24). Model 2: Galaxies form stars at constant rates in selected times (t1,t2) where t0 < t1< t2 < tEND In both model scenarios, we vary tEND and at each step compute the colors for 10,000 galaxies by interpolation and integration of the BC (2003) solar metallicity models. Then find tEND that yields the best match to the observed intrinsic scatter of a given early type population (E or S0) STScI Colloquium

  16. Modeling the scatter • Model 1: • Minimum age of last epoch of SF in CL1252 ellipticals is 1.6 Gyr prior to z=1.24 lookback time (zEND = 1.9) • Mean Luminosity weighted age is 3.3 Gyr (z = 3.6) with a scatter of ~30% • For S0’s: zEND = 1.5 with age scatter ~44% • Model 2: • Minimum age of last epoch of SF in CL1252 ellipticals is 0.53 Gyr prior to z=1.24 lookback time (zEND = 1.4) • Mean Luminosity weighted age is 2.6 Gyr (z = 2.7) with a scatter of 38% • Even though epoch of last star formation activity is “recent” the mean age of the ensemble is still high. • For S0’s: zEND = 1.3 with age scatter ~47% • Both models give observed colors that match the observations. STScI Colloquium

  17. Mean Spectral Features in CL1252 (z=1.24) Local Elliptical Significant Hin absorption seen in co-added spectrum from 10 brightest early type cluster members Most of the early type galaxies contain “post-starburst” stellar population Consistent with a formation redshift of zF ~ 3 Local Spiral Rosati et al. 2003 deMarco et al. 2004, in prep STScI Colloquium

  18. Constraints from the Evolution of the Mass-to-Light Ratio Results for CL1252 are preliminary! (good to within ~20%) M  2R L  R2 M/L  2/ R Jorgenson, Franx & Kjaegaard 1995 Kelson et al 2000 Holden, van der Wel et al 2004 E+A Galaxy Van Dokkum & Stanford 2003 The M/L evolution is ~1.1 magnitudes in the rest-frame B band between z=0.33 and z~1.25. This amount of evolution is consistent with a solar metallicity BC03 SSP model with an initial star formation epoch at z=3. STScI Colloquium

  19. Within central 1.5 Mpc region of distant (z ~ 0.8 - 0.9) clusters, the fraction of galaxies with OII EQW > 15 Å is ~45% (Postman, Lubin, Oke 2001), substantially higher than the 10 to 20% active fraction seen in the centers of 0.2 < z < 0.55 clusters (Balogh et al. 1997) deMarco et al. 2004 SFRs in z~1 clusters are also substantially higher than in z~0 clusters. Within central 1 Mpc, evidence for suppressed SFRs relative to those at larger radii. STScI Colloquium

  20. Ages of Early Type Cluster Galaxies • Ellipticals are well established in x-ray luminous clusters when universe was ~1/3 its present age • There is no significant evolution in the CMR (other than expected from passive evolution) • Photometric and spectroscopic data suggest a mean formation era of z ~ 3 with a spread in formation times of ~34 (±15) % (~0.7 Gyr) • Star formation is higher and more frequent in z>0.8 cluster S0s and spirals than what is seen today STScI Colloquium

  21. Goto et al 2003 Poggianti 2000 Are the morphologies of cluster galaxies evolving? • What we know: • The relative fraction of galaxy morphologies depends on density (Dressler 1980, Postman & Geller 1984) and/or on clustocentric radius (Whitmore & Gilmore 1993) • Physical processes exist that can alter galaxy morphology on timescales much less than the current age of the universe: ram pressure, tidal disruption, mergers • Some data suggests there is detectable evolution in the morphological composition of clusters over the past ~5 Gyrs (z~0.5 to the present epoch) Quilis, Moore, & Bower 2000: Ram pressure induced evolution of gaseousdisk moving thru hot ICM - all HI gas is stripped in 100 Myr STScI Colloquium

  22. Classifying Galaxies • Visually • Over 3500 galaxies with i,z < 24 classified. No selection in color or position. Classifications done in bandpass that is closest to the rest-frame B-band. • Methodology: ~3 team members (MP+) classify galaxies using a common reference set. Agreement in E, S0, Sp, Irr typically 75 - 85%. No systematic errors between classifiers detected. • Morphological “k-correction” has been shown to be a small effect (e.g., Bunker et al. 2000; Windhorst et al. 2002) • Machine-generated Parameters • Compactness, Asymmetry, BPZ Spectral template type show good correlations with visually determined type STScI Colloquium

  23. S0/a E S0/E Sa E/S0 E E S0/a Sb/Sc S0/E S0/E S0/E S0/a Sc/Sd Sa or later S0/E Sb/Sc E E S0/a E S0/E E S0/a S0/E E/S0 E S0/a Sb or later E S0/a Sa or later S0/E Sb or later Sb/Sc E Sc/Sd S0/E Sb/Sc E/S0 Sa or later S0/a S0/a E/S0 E/S0 E Sb or later S0/a Sb/Sc 22.2 mag 23.0 mag STScI Colloquium

  24. 0.33 ≤ zB≤ 0.53 0.53 ≤ zB≤ 0.73 0.73 ≤ zB≤ 0.93 0.93 ≤ zB≤ 1.13 1.13 ≤ zB≤ 1.33 1.33 ≤ zB≤ 1.53 Photometric Redshifts STScI Colloquium

  25. CL0152 + MS1054: BPZ Sample Spectroscopic Sample 10 100 1000 10 100 1000 Density (Galaxies Mpc-2) Morphology-Density Relation @ z = 0.83 Postman et al 2004, in prep STScI Colloquium

  26. Morphology-Density Relation @ z = 1.24 Postman et al 2004, in prep STScI Colloquium

  27. Morphology-Radius Relation Whitmore & Gilmore 1993 STScI Colloquium

  28. All Galaxies (photo-z sample) CL1252-2927 CL0152-1357 STScI Colloquium

  29. Spiral Galaxies (photo-z sample) CL1252-2927 CL0152-1357 STScI Colloquium

  30. S0 Galaxies (photo-z sample) CL1252-2927 CL0152-1357 STScI Colloquium

  31. Elliptical Galaxies (photo-z sample) CL1252-2927 CL0152-1357 STScI Colloquium

  32. CL1252 MS1054 CL0152 1.24 Evolution of the Early Type Population Fraction Lubin, Oke, Postman 2002 STScI Colloquium

  33. 0.83 1.24 Poggianti 2000 Postman et al 2004, in prep No significant evolution of morphological population between z=1.24 (8.5 Gyr ago) and z=0.4 (4.3 Gyr ago) STScI Colloquium

  34. Evolution of Morphological Composition in Clusters • Morphological segregation is in-place by z=1.24, at least in clusters with x-ray luminosities greater than 2.5 x 1044 erg/s. M-D and M-R relations are qualitatively consistent with what is seen locally - spiral galaxies are not common in dense environments. • Given the irregularity** of the galaxy distributions, the presence of a strong M-D relation suggests that density, rather than clustocentric radius, may be the more fundamental variable. • There is no strong evolution in the early type fraction in x-ray selected clusters between z ~ 1.24 and z ~ 0.5 - but, as always, a larger sample is needed. • This may suggest that morphological fractions in current epoch clusters are the result of more recent environmental interactions (a la MORPHs) • ACS / WFC enables relatively easy and robust early vs late type classification down to i = 23 mag & down to i = 24 mag with care. STScI Colloquium

  35. Brightest Cluster Galaxies BCG Formation Simulation by J. Dubinski (1998) • BCGs could exhibit significant photometric & morphological evolution between z~1 and now. • What fraction of z~1 BCGs appear to be in process of merging? • How does the rest-frame B-band BCG luminosity in our z~1 clusters compare with current epoch BCGs? 10 Gyr in 15 seconds STScI Colloquium

  36. Brightest Cluster Galaxies CL0152-13 MS1054 CL1604+4304 Elliptical Elliptical Sb/Sc S0/a S0/a Elliptical CL1604+4321 CL0910+54 CL1252-29 STScI Colloquium

  37. BCG Mergers? • MS1054 has asymmetric outer isophotes. • CL1252 BCG “pair” leave significant residuals when best-fit elliptical isophotes subtracted - suggestive of tidally stripped stars. This pair will likely merge within a few Gyr. • CL0152 BCG is well-fit by concentric elliptical isophotes. STScI Colloquium

  38. BCG Luminosity Evolution z ~ 1 BCG exhibit a similar dispersion in their rest-frame B-band luminosities (~32%) as their z=0 counterparts M2 - M1 in all but one of these z~1 clusters is smaller (<0.13 mag) than that in ~90% of the z~0 rich Abell clusters [Exception is MS1054 which has 0.36 mag contrast] We expect some of these BCGs to undergo a doubling in mass by z~0.5 (e.g., CL1252) STScI Colloquium

  39. Mapping the Cluster Mass Distribution • Key questions: • Is the distribution of luminous matter an accurate tracer of the total mass? Are substructures seen in x-rays and galaxies reflected in mass as well? • Is the mass estimate from gravitational lensing consistent with other (x-ray, kinematic) mass estimators? STScI Colloquium

  40. Chandra imaging: Evidence for On-going Cluster Accretion CL0152-1357 MS1054-0321 CL1252-2927 Rosati et al. 2002 STScI Colloquium

  41. Cluster Mass Distribution: CL0152 Luminosity Density for cluster members M. Jee et al. 2003 STScI Colloquium

  42. Cluster Mass Distribution: MS1054 Luminosity Density for cluster members M. Jee et al. 2003 STScI Colloquium

  43. ------ NIS model ------ NFW model ------ X-ray, T=[5.6, 6, 6.4] keV Cluster Mass Distribution: CL1252 Luminosity Density for probable cluster members Contours show the surface mass distribution as derived from the co-added i+z band image. The detection shown is significant at the 6 level. Lombardi, Rosati et al. 2003 STScI Colloquium

  44. Arc A Arc B Gravitational arcs discovered in CL1252-2927 @ z=1.24 Galaxy@ z= 3.36 STScI Colloquium

  45. Cluster Mass Distribution • Strong lensing is detected in at least two clusters at z=0.83 and z=1.24. Weak lensing detected in all z>0.8 clusters studied so far. • Galaxies, ICM, and mass exhibit qualitatively similar distributions. The frequency of significant substructure or elongated cluster galaxy distributions tends to increase with redshift (cf. Lubin & Postman 1996) - consistent with our ACS observations and current theoretical models. • Lensing maps reveal, however, that highest galaxy overdensities don’t always correspond to highest mass peaks, suggesting variations in M/L within a cluster. • Lensing mass profile in good agreement with x-ray temperature and galaxy kinematics. STScI Colloquium

  46. Finding Protoclusters at z > 1.3 • Powerful High-z Radio Galaxies: Forming BCGs? • Amongst the brightest galaxies at every z (e.g. De Breuck et al. 2000) • Merging of multiple L* clumps (e.g. Pentericci et al. 1998) • ~100 kpc envelopes of emission-line gas (e.g. vOjik et al. 1996) • LFIR > 1013 Lo implying SFR > 2000 Mo/yr • Highly clustered (e.g. Blake & Wall 2003, Overzier et al. 2003) • SM blackholes powering AGN • Associated with GALAXY OVERDENSITIES! WFPC2 (F606W) image of PKS1138-262 at z=2.2 with VLA radio contours (Pentericci et al. 1998) STScI Colloquium

  47. NARROW-BAND LYA IMAGING of POWERFUL RADIO GALAXIES has revealed z > 2 ‘PROTOCLUSTERS’ (Keel et al. 1999, Pentericci et al. 2000, Venemans et al. 2002,2004, Kurk et al. 2001,2003) • TN J1338-19 at z = 4.11: • 33 confirmed Ly emitters (Venemans et al. 2002, 2004 in prep) • Velocity dispersion ~350 km/s • Comparable to mass of Coma cluster • However, Lya only detects about ~20% of Lyman Break galaxies (Steidel et al. 1999, Shapley et al. 2001) VLT/FORS Lya at z = 4.11 STScI Colloquium

  48. HST/ACS observations of TN J1338 at z = 4.11 18 orbits (5g,4r,4i,5z), single pointing. Look for LBG population associated with protocluster at z~4: g-r > 1.5, g-r > (r-i)+1.1 r-i < 1.0 i < 27 Miley et al. 2004; Overzier et al. in prep. STScI Colloquium

  49. 56 LBGs to iAB=27 Cloning (R. Bouwens) of B-dropouts suggests 3-5 sigma overdensity of LBGs compared to GOODS (Giavalisco et al.); Concentrated towards radio galaxy. 12 Lya emitters Radio Galaxy 2 arcsec/16 kpc iAB=23.3 STScI Colloquium

  50. R  H(z)-1 ( virial velocity) R  H(z)-2/3 ( virial mass) No evolution TN1338 z=4.1 Does the structure of galaxies depend on their Ly emission? Preliminary result from Overzier et al. 2004 Ferguson et al. 2003 Bias? Lya = invf(L,SFR) STScI Colloquium

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