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Dynamical Models of Elliptical Galaxies in z=0.5 Clusters: 

Dynamical Models of Elliptical Galaxies in z=0.5 Clusters Measuring M/L Evolution without Fundamental Plane Assumptions Roeland van der Marel (STScI) In Collaboration with: Pieter van Dokkum (Yale)

M/L Evolution using FP: 

M/L Evolution using FP Distant galaxy observations yield effective quantities High resolution imaging: R, I Deep Spectroscopy:  Fundamental Plane (FP) R = C   I  , C = FP zeropoint FP zeropoint evolution w.r.t. Coma  M/L evolution Provided that assumptions are valid M/L evolution galaxy ages Constraint on galaxy formation theories

Results: 

Results Data New: 3 clusters at z=0.5 Literature: 11 other clusters Literature: field galaxies Interpretation Homogeneous analysis Various IMFs, progenitor bias Results for M andgt; 1011 M Cluster Galaxies: d log (M/LB) / dz = -0.555  0.042 z(formation) = 2.0  0.2 for 'standard' IMF z(formation) can be larger for top-heavy IMF Field Galaxies: younger by 4.1  2.0% (~0.4 Gyr) vD andamp; vdM (2006, Paper I) Cluster Field

Motivations for More Detailed Analysis: 

Motivations for More Detailed Analysis FP to M/L conversion relies on untested assumptions R, I,  and internal structure may evolve with z; not just M/L Plausible models exist in which M/L does not follow FP (e.g., Almeida, Baugh andamp; Lacey 2006) FP results counter-intuitive given hierarchical formation scenarios Some assumptions can be avoided by using more data R, I  Surface brightness profile + axial ratio   Resolved velocity dispersion and rotation velocity profiles How: Modeling of Internal Dynamical Structure Tools well-developed and tested in local universe vdM andamp; vD (2006, Paper II)

Sample & Data: 

Sample andamp; Data Three MORPHS clusters CL 3C295 (z=0.456) CL 0016+1609 (z=0.546) CL 1601+4253 (z=0.539) 25 visually-classified early-type galaxies 20 ellipticals, 2 E/S0, 1 S0/E, 1 SO, 1 S0/Sb HST/WFPC2 imaging (Archival) Keck/LRIS spectroscopy (New)

Models: 

Models Oblate axisymmetric Constant ellipticity and PA Parameterized (R,z) Inclination chosen statistically Potential from Poisson equation Dynamics from Jeans equations DF Assumption: f(E,Lz) Projection along line-of-sight Convolution with seeing, slit width and pixel binning Comparison to V and  profiles log (R[arcsec]) chosen to fit photometry Lucy deconvolution + ellipse fitting

Data-Model Comparison: 

Data-Model Comparison Kinematical profiles Pixel size 0.215' Extent ~0.7' (4.3 kpc) Modeling spatial resolution essential Seeing 0.7'-0.9' Slit width 1.1' Acceptable fits Model parameters M/LB k [similar to (V/)*] R [arcsec] Cross-correlation + Gaussian LOSVD fitting

Rotation Properties : 

Rotation Properties Most luminous galaxies at z=0.5 rotate too slowly to account for their flattening Consistent with rotation properties of local ellipticals Isotropic Rotator

Kinematical Identification S0 galaxies?: 

Kinematical Identification S0 galaxies? More rapidly rotating galaxies among visually classified ellipticals at z=0.5 than z=0 Probably more misclassified S0s at z=0.5 Only raises the S0 fraction of the three target clusters mildly (16%  22%) Insufficient to explain strong S0 evolution from z=0.5 to present z=0.5 z=0

M/L in the Local Universe: 

M/L in the Local Universe Detailed dynamical modeling of large samples vdM (1991), Magorrian et al. (1998), Kronawitter et al. (2000), Gebhardt et al. (2003) Found that M/L correlates with L or M Cappellari et al. (2006) Found that M/L correlates even more tightly with  New homogenized compilation of these model results Transformed to B-band M/L Individual distances from SBF method (Tonry et al. 2001) Result log(M/L)B = (0.8960.010)+(0.9920.054) log(eff/200 km/s) Slope steeper than in I-band (0.82 0.06, Cappellari et al.)

Local Results: Modeling Comparison: 

Local Results: Modeling Comparison Excellent agreement between different studies Systematic modeling errors small

Evolution of the M/L – sigma relation: 

Evolution of the M/L – sigma relation d log (M/LB) / dz = -0.529  0.049(random)  0.071(sys) Consistent with FP zeropoint evolution (for M andgt; 1011 M)

Dependence on  (or Mass): 

Dependence on  (or Mass) FP: more evolution for galaxies of low  FP slope becomes steeper with redshift Also seen in many other samples Usually interpreted as difference in age M/L vs.  relation: evolution independent of  Slope same at z=0.5 as z=0 No difference in age implied

Methodological Differences: 

Methodological Differences Why do FP evolution and M/L-  evolution differ for low- galaxies? Other quantities than M/L may be evolving (R, I, , structure, …) [relations not parallel!] (+) Rotation may be important: affects M/L but not FP [aperture corrections?] (?) Dynamical models may suffer from limited resolution [systematically errors?] () Virial M/L = (K/2G) 2/RI Isotropic Rotator

Conclusions - Distant Elliptical Galaxies: 

Conclusions - Distant Elliptical Galaxies To lowest order: FP evolution = M/L evolution z(form, M andgt; 1011 M, cluster) = 2.0  0.2 ('standard' IMF) field Galaxies: younger by 4.1  2.0% (~0.4 Gyr) When considered more carefully, many subtle effects come into play Quantities other than M/L may be evolving Rotation may be relevant Steepening of FP tilt with redshift does not necessarily imply that low-mass galaxies are younger

Conclusions – What’s next: 

Conclusions – What’s next Good reasons to move beyond global properties Available data and tools allow detailed modeling of internal dynamical structure Extend similar analyses to different samples Study combined M/L and color evolution JWST/NIRSpec will further revolutionize this field