1. Naoyuki Tamura (University of Durham) The Universe at Redshifts from 1 to 2 for Early-Type Galaxies ~ Unveiling “Build-up Era” with FMOS ~

2. Outline  Summary  Galaxy population at z 2  To understand the histories of early-type galaxies … Does stellar population tell us all ? What are expected at 1 < z < 2 ? Revisit the starting point :  How can the strengths of Subaru/FMOS be exploited ?  Extremely Red Objects Limitation due to lack of spectrum

3. NGC 3923 : E4 SFR t Evolutions of CM relation & Fundamental Plane up to z ~ 1 look passive. No active star formation is on-going at z=0. The bulk of stars seem to be old.   Stars in Elliptical Galaxies Star formation Passive evolution stopped. z > 2 ?

4. Ages at z = 0 from spectroscopy  [km/s] 100 200 300  [km/s] 60 100 180 Trager et al. (2000) Caldwell et al. (2003) Cluster Group Field Virgo Field

5. What does “age” tell us ? “Galaxy formation history” - when did a galaxy become an elliptical ? “Star formation history” - when did most of the stellar content form ? ? Monolithic Collapse Scenario Starburst Gas rich Hierarchical Merging Scenario Major merger Luminosity Function Stellar Population

6. Luminosity Function of E/S0s at z < 1 COMBO-17 ~ 2800 arcmin^2, R < 26 (5  ), ~ 25000 galaxies ~ 5000 galaxies on the red sequence at 0.2 < z < 1.2. Rix et al. (2004) GEMS High resolution imaging follow-up with ACS/HST Most of them (~ 85 %) seem to be morphologically early-type. Evolution of luminosity function

7. Luminosity Function of E/S0s at z < 1 COMBO-17 Bell et al. (2003) About half of the local population were already in place at z ~ 1 ?

8. Luminosity Function of E/S0s at z < 1 Morphology Spectroscopy Multi-band photometry Im et al. (2002): DEEP Groth Strip survey Chen et al. (2003): Las Campanas IR survey Pozzetti et al. (2003): K20 survey Suggest a mild evolution up to z ~ 1 50 ~ 80 % were already in place at z ~ 1 ? (HST/WFPC2 images)

9. Any “bona-fide” E/S0s at z > 2 ? Radio galaxies Rocca-Volmerange et al. (2004) Pentericci et al. (2001) (z = 2.3)(z = 2.4) Passive evolution prediction  (z = 10, M = 10 M ) f 12

10. Any “bona-fide” E/S0s at z > 2 ? Lyman Break Galaxies SCUBA Galaxies Red galaxies from FIRES No clear Hubble sequence ? A population of passive E/S0s have not revealed yet ? Stellar mass ~ 10 M J-K ~ 2 or redder z = 2 ~ 3 (?) z > 3 Strong clustering ~ 2.5 (1 < z < 4) SFR ~ 1000 M /yr SFR ~ 1 - 100 M /yr Starburst galaxies ? 10    Investigations are on-going...

11. How can they be linked at z = 1 ~ 2 ? Star forming galaxies Passive evolution phase Luminosity function of passive galaxies and its evolution at z = 1 ~ 2 A number of post-starburst galaxies ? Half or more of the local population show up in this epoch ? Consumption ? Distant clusters are revealed ? Through redshift survey … somehow Environmental effect ?

12. Extremely Red Objects (EROs) Good candidates for passive ellipticals at z > 1. Heterogeneity Although the colour criterion seems to work for isolating passive ellipticals … Luminosity function of EROs has been studied. Our understandings of EROs have been limited due to lack of spectra. R-K > 5 / I-K > 4 (Cimatti et al. 2003; Yan et al. 2004)

13. Smith et al. (2002) Smail et al. (2002) Mannucci et al. (2002) Colour criterion to classify EROs Cimatti et al. (2003)

14. Miyazaki et al. (2002) Caputi et al. (2004) Evolution of ERO LF at z > 1 ?

15. Extremely Red Objects (EROs) Good candidates for passive ellipticals at z > 1. Heterogeneous Although the colour criterion seems to work for isolating passive ellipticals … Luminosity function of EROs has been studied. Photo-z :  z ~ 0.3 at z ~ 1.5 Our understandings of EROs have been limited due to lack of spectra. Too coarse to investigate evolution at 1 < z < 2 ? R-K > 5 / I-K > 4 (Cimatti et al. 2003; Yan et al. 2004)

16. What we need to do are : To perform deep spectroscopic observations and to get quality data. Redshift Classification Absorption line To collect a large number of galaxies at z > 1 from a large survey area. Good statistics Cosmic variance

17. The other word of FMOS (1) Wide spectral coverage in the NIR Spectral features in the rest frame optical are available for galaxies at z > 1. Combination with UKIDSS-DXS Optimal for redshift survey. (& Subaru/Suprime-Cam)   Allows us to efficiently pick up candidates for galaxies at z > 1 with colour information.  Luminosity can be derived with the aid of redshift. 

18. The other word of FMOS (2) Wide field & high multiplicity 30’ FMOS-FOV / 400 fibres ~ 200 fibres will be available for objects in one exposure. Better statistics Longer integration Highly efficient !

19. Simulated Spectrum H = 20.5 mag Old stellar population (3.0 Gyr age) at z = 1.5 8 hr integration (1 hr x 8) & 5 pix. binning 4000 A G-band HH Mgb

20. Gemini Deep Deep Survey 4 x 30 arcmin^2 field Nod & shuffle technique Gemini Multi-Object Spectrograph > 30 hr integration per field Fibre Multi-Object Spectrograph FOV ~ 700 arcmin^2 200/200 fibres for object/sky (+ Double beam switching obs. ?) ??? hr integration per FOV ???????????????? Survey

21. Simulated Spectrum H = 22.0 mag Old stellar population (3.0 Gyr age) at z = 1.5 100 hr integration (1 hr x 100) & 5 pix. binning 4000 A G-band HH Mgb NaD

22. Summary Luminosity function of passive galaxies Evolution of LF between z = 1 and 2. A number of post-starburst galaxies ? To understand history of early-type galaxy Luminosity Function Stellar Population Bridging two epochs ? z < 12 < z Need to look at absorption lines Star forming galaxiesPassive evolution Wide field & high multiplicity can be exploited for deep observation.