1. Cambridge, September 9th 2004 Spitzer discovery of luminous infrared galaxies at 1<z<2.5 Emeric Le Floc’h University of Arizona  “A starry sunset seen by MIPS” … and * Casey Papovich * Pablo Pérez-González * Eiichi Egami * Hervé Dole * Almudena Alonso-Herrero * George & Marcia Rieke + the MIPS instrum. team  see also Casey’s talk tomorrow !

2. Cambridge, September 9th 2004 Spitzer discovery of luminous infrared galaxies at 1<z<2.5 Emeric Le Floc’h University of Arizona  “A starry sunset seen by MIPS” I) MIPS capability for deep surveys 2) What we learnt from the counts 3) A possible new model ? 4) IR luminosity functions 5) IR luminous sources in the redshift desert

3.  “A starry sunset seen by MIPS” Cambridge, September 9th 2004 MIPS GTO cosmological surveys

4. Cambridge, September 9th 2004 MIPS GTO cosmological surveys N E Bootes field - 24 μm  © Houck/Rieke/Soifer/  Weedman MIPS : - 24, 70 and 160 μm - large area coverage - unprecedented sensitivity in the IR * Shallow survey (~90s) : (IRS team/M.Rieke) - 9 deg, ~32000 sources - Comp. 80% : 0.3 mJy @ 24 μm 2 3.2 deg

5. Cambridge, September 9th 2004 MIPS GTO cosmological surveys MIPS : - 24, 70 and 160 μm - large area coverage - unprecedented sensitivity in the IR * Shallow survey (~90s) : (IRS team/M.Rieke) - 9 deg, ~32000 sources - Comp. 80% : 0.3 mJy @ 24 μm 2 * Deep surveys (~1400s) : - CDFS, HDF-N, Lockman Groth Strip..... (~0.6 deg ) - Comp. 80% : 80 μJy @ 24 μm 2 Bootes CDFS N E Bootes field - 24 μm  © Houck/Rieke/Soifer/  Weedman 2’

6. Cambridge, September 9th 2004 The MIPS number counts The strong evolution revealed by ISO and SCUBA is clearly observed by MIPS at 24, 70 and 160  m. 24  m (Dole et al. 2004) (Papovich et al. 2004) no evolution   but the turn-over in the 24  m different.  counts is at lower flux than expected  based on pre-launch models !

7. Cambridge, September 9th 2004 Phenomenological model * 2 populations of sources : starburst and cold galaxies Lagache et al. 2004 (an update of Lagache et al. 2003) : * Library of IR templates * A z=0 IR luminosity function based on the IRAS data  Find the evolution to fit the ISO/Spitzer/SCUBA number counts (Lagache et al. 2004) new templates old templates new evolution of the IR luminosity old evolution

8. (Lagache et al. 2004) 24  m 0<z<0.3 0<z<0.8 0<z<1 0<z<1.3 0<z<2 0<z<  Cambridge, September 9th 2004 old templates Results and Predictions Lagache et al. 2004 Lagache et al. 2003 * 30% of sources at z>2 for 24  m fluxes~0.2mJy (3x more sources at z>1.5 than predicted before) * The peak of the contribution of sources at 0<z<z_lim is shifting to lower fluxes when z_lim increases (Papovich et al. 2004) LIRGs/ULIRGs in the redshift desert (for fluxes > 80 μJy at 24 μm)

9. Cambridge, September 9th 2004 old templates MIPS observations of the CDFS Lagache et al. 2003 24217 sources from COMBO-17 (x1/5) MIPS 24  m sources (MIPS sources with spec. z) * Spectr. z : VVDS, GOODS, Chandra follow-up * Photometric z : COMBO-17  775 arcmin^2, 5240 MIPS sources, 442 with spec.z (8%), 2678 with phot.z : total=3120 sources MIPS COMBO-17 VVDS 30’ N E (Le Fèvre et al., Vanzella et al., Szokoly et al., Wolf et al.)

10. Cambridge, September 9th 2004 MIPS sources at 0<z<1 Flux 24 μm (mJy) 0.11 dN/dS x S^2.5 (arbitrary unit) Papovich et al. 2004 Total “MIPS/COMBO” area 0<z<0.3 0<z<0.8 0<z<1 0<z<1.3 ?

11. Cambridge, September 9th 2004 MIPS sources at 0<z<1 Flux 24 μm (mJy) 0.11 dN/dS x S^2.5 (arbitrary unit) Papovich et al. 2004 Total “MIPS/COMBO” area * Contribution of z<1 sources could be under- estimated * Need better statistics (i.e., add other fields) * Peaking at constant flux How to refine the model ? * LF evolution ? * PAH templates ?

12. Cambridge, September 9th 2004 24 μm  IR luminosity ? Redshift Observed 24 μm flux (mJy) 80 μJy 10, 10, 10, 10, 10 L  9 10 11 1213 * A tight mid-IR / far-IR / total IR in the local Universe (e.g., Chary & Elbaz 2001) * Seems to be still OK at high z (P. Appleton ‘s talk) * SEDs consistent with PAHs at z~0.8 (D.Elbaz ‘s talk) - If using local templates, L_IR should be accurate within a factor of 2, depending on the library - Possible caveats : evolution with metallicity ? (Dale et al. 2001, Lagache et al. 2003/4, Chary & Elbaz 2001, Chanial 2003) Z>1.5 (24 μm + 70 μm ??  see Casey’s talk )

13. Cambridge, September 9th 2004 IR luminosities in the CDFS Redshift 10.1 0.01 L_IR (L )  LIRGs (~15<SFR<150 M /yr) ULIRGs HyLIRGs (COMBO-17) 

14. Cambridge, September 9th 2004 IR luminosity functions in the CDFS * Faint-end slope steeper than predicted by Lagache et al.  but no steepening of the local LF * Strong evolut. in luminosity : (1+z) 3-4 * Modest evolut. in density (exclude a pure density evol.) L_IR (L )     LF (/Mpc^3/mag) 0.85<z<1 0.7<z<0.85 0.6<z<0.7 0.5<z<0.6 Lagache et al. 2004 (local LF)

15. Cambridge, September 9th 2004 old templates MIPS in the redshift desert * Use of “IRAC” photo-z : (probing the **hump** of the old stellar population continuum) * Spectroscopy with medium resolution, catching absorption lines (data from DEEP) (Le Floc’h et al. 2004)

16. Cambridge, September 9th 2004 old templates Multi- propert. of z>1 MIPS sources Lagache et al. 2003 IRAC 8μm MIPS 24μm R band VLA/SCUBA IRAC 3.6μm IRAC 4.5μm (Alonso-Herrero et al. 2004) (Egami et al. 2004, Ivison et al. 2004) * Detection of VLA/SCUBA/MAMBO sources with MIPS : * Detection of X-ray sources at 24 μm : submm wavelengths (  efficient way to catch Infrared luminous galaxies at z>1 ) (e.g. Egami et al. 2004) pre-selection at radio/ up to z~1.6 with IRAC photo-z’s so far (Alonso-Herrero et al. 2004)

17. Cambridge, September 9th 2004 Perspectives... * Source density, luminosity functions at z>1 ??? - Cosmic variance ?  same work must be done in other fields - MIPS sources without z, which consequence for LF at z<1 ? - AGN contamination ? - SED templates, PAHs ?? - How does the LF depend on SEDs ? * Issues  STILL A LOT OF WORK !!  too early !…. (need good photo-zs)

18. Cambridge, September 9th 2004 Cosmic variance in the CDFS Courtesy Eric Bell Redshift B-band lumin. density Total/CDFS CDFS Total COMBO-17 (3 fields 30’x30’)

19. Cambridge, September 9th 2004 60 μm lumin. Functions in the CDFS L_IR (L )  LF (/Mpc^3/mag) 0.85<z<1 0.7<z<0.85 0.6<z<0.7 0.5<z<0.6 (local LF) L_IR (L )  LF (/Mpc^3/mag) L_IR (L )  LF (/Mpc^3/mag) L_IR (L )  LF (/Mpc^3/mag) L_IR (L )  LF (/Mpc^3/mag) L_IR (L )  LF (/Mpc^3/mag)