1. GEMS Collaboration Meeting Baltimore, Jan 20-21, 2003 What do we want to accomplish?  Get to know each other  Take stock of our status quo –Data, software (tools),goals,...  Better define data products  Prioritize science goals –Define approach –Clarify team responsibilities –(Re-)define schedule  GEMS vs. Other current activities

2. 2 Galaxy Population over the last 10 Gyrs  How many stars have formed since z~1.2 ? –In which Galaxies? –Mostly during in star-bursts, or “quiescently”? –Which galaxies are “old” already?  How did the clustering of galaxies evolve ? –Mass clustering vs. galaxy bias. –Always a morphology-density relation?  When and how did bulges and disks form ? –How did the merger rate evolve? –Is there an „angular momentum“ problem –Do disks grow inside out?  What makes AGNs light up? –Dramatic drop in AGN lum. density since z~1

3. 3 What Data do we Need ? (to tackle this via “look-back” observations) Galaxy properties as a function of: –Redshift/Epoch with  t/t H ~1 Note: z=1.2  t look-back = 10 Gyrs –Luminosity –Spectral Energy Distribution (SED) –Internal structure (size, bulge-to-disk, etc.) –Environment  a multi-dimensional parameter space + account for large-scale fluctuation in the galaxy and mass distribution. + include “typical” galaxies at all epochs i.e. reach below L * at all redshifts

4. 4 Survey Requirements Several 10,000 galaxies with –Redshifts to z>1 (good to a few percent) –Faint flux limit m r ~24 –SEDs, including (rest-) UV and optical Several large fields –Co-moving size > 5 Mpc High-resolution (0.1”) imaging –typical scale lengths are 0.3 asec –two-color  rest-frame B at all z

5. 5 Existing Faint Surveys  CFRS –Lilly, LeFevre, et al. –I<22.5, 591 galaxies  CNOC2 –Yee, Carlberg etal. –R<21.5, z<0.55,2000 galaxies  HDF –Williams etal., Cohen etal. –redshifts for 200 objects  Medium Deep Survey – Keck spectroscopy

6. 6 CFRS Luminosity Function

7. 7 Status quo: Morphologies

8. 8 Status quo: bars

9. 9 Status quo: Bulge-Disk Fitting: GIM2D (Simard etal 1999) Data: somewhat heterogeneous HST imaging

10. 10

11. 11 Status quo: disk sizes

12. 12 Status quo: Disk size function Lilly et al 1998 HST images of CFRS galaxies

13. 13 Status quo: merger rate

14. 14 Surveys at Hand  COMBO-17 C. Wolf, K. Meisenheimer (co-PIs), E. Bell, C. Maier, H.-W. Rix, S. Phleps, A. Borch + Edinburgh, Bonn –Data from WFI at the MPG/ESO 2.2m on La Silla  GEMS –2-color, deep HST/ACS mosaic ( ~180 x HDF area)

15. 15 GEMS: Key to “internal structure” ( G alaxy E volution from Morphology and S EDs)  Large HST program (125+50 orbits) to image “extended-Chandra-Deep-Field-South” –10,000 redshifts from COMBO-17 –9x9 ACS tiles  150 x HDF –V and z –Limit: m z ~27.5

16. 16 GEMS 58 1.5% of total

17. 17 COMBO-17 (~0.7”) vs. HST/ACS

18. 18..and we do have the redshifts.. ~1.2´x 2.2´ (0.003 of the total field)

19. 19 GEMS: Top-Level Project Steps  Image acquisision, reduction  Object Detection+Match-up  Fitting/Morphology quantification  Selection/fitting simulation  Structural „master catalog“  Empirical results  Link to theoretical predictions  Model-dependent results

20. 20 GEMS Analysis: Basic Steps Task ResponsibleDate Complete (%) Data Acquistion Caldwell, Vick, Peng 100% P ~95% E Tile Reduction Caldwell~90% D ~50% E Object Detection McIntosh~90% D ~20% E Galfit CodePeng Häußler,Jogee ~95% D GIM2DMcIntosh~95% D

21. 21 Task ahead: Fitting 30,000 galaxies

22. 22 GEMS vs past work  30-fold number increase  Well defined sample with ample external information  z-band ACS imaging

23. 23 Our competitive edge  COMBO-17 full catalog not yet published  GEMS mosaic largest HST image mosaic of sufficient depth (perhaps for a while...)  Comprehensive team experience BUT.....  GEMS data instantly public  With DEEP and VMOS, the COMBO-17 data will loose their uniqueness within a year

24. 24 Top-Level Science Goals  How did stellar disks evolve/grow? –(Disk) size function –L vs r eff, Tully-Fisher  Evolution of bulges/ellipticals –B/D ratios, growth of „old“ pops. –L vs r eff, fundamental plane  Evolution of merger rate vs star burst rate  Did „internal evolution“ play a role? –Bar statistics  When are galaxies AGNs? –Host galaxies

25. What do we want to accomplish?  Get to know each other  Take stock of our status quo –Data, software (tools), responsibilities  Better define data products  Prioritize science goals –Define approach –Clarify responsibilities –(Re-)define schedule –set of possible 1.generation papers  GEMS vs. Other current activities

26. 26

27. 27 Spectroscopy goals for COMBO-17/GEMS  Redshifts –outliers? –present median precision  180 Mpc –GEMS image contains 6 x more galaxies with good photometry  Spectral features –Balmer emission/absorption lines –AGN vs. star-formation diagnostics  Kinematics –Stellar and emission lines (stellar) masses from SEDs, spectra and kinematics Star-formation rates and metallicity Interaction rates – local velocity dispersion