SWIRE view on the "Passive Universe": Studying the evolutionary mass function and clustering of galaxies with the SIRTF Wide-Area IR Extragalactic Survey (SWIRE)

Formation of massive ellipticals, S0’s and galaxy spheroids Formation of large disks

log ρ(>z) - 100% - 10% The cumulative Stellar Mass Density vs. Star Formation Rate - 1%

Photometric estimates of the stellar mass in high-z galaxies t=9 Gyr 7 Gyr 5 Gyr 1 Gyr 3 Gyr z=1.27

MASSES of E/S0 galaxies in the HDFs vs. redshift ( Rodighiero, Franceschini & Fasano 2001) Sample of 69 E/S0's to K=20.2 morphologically selected over 11 sq.arcmin in HDFN, HDFS & NICMOS Dotted: Model 1 Continuous: Model 2 Salpeter IMF with 0.15<M<100 M o

Redshift distribution for E/S0 in the HDFs & NICMOS vs. predictions for different z F

Typical SEDs of morphologically- classified E/S0 galaxies Model 1 Model 2 Franceschini et al. (1998)

Rest-frame colours for early-type galaxies compared with model SSPs

Passive Ellipticals Dusty Starbursts Sample of 45 ERO's selected K<19.2 over 52 sq.arcmin (Cimatti et al. 2001)

Moriondo et al. (2000): study of Extremely Red Objects selected in K

Stanford et al. (1998) Evidence for a different star-formation history in high-density environments [accelerated with cosmic time wrt. the field]? Solid line: z F =5, dashed line: z F =2 "Colors of high-z cluster galaxies"

Spatial clustering of EROs (high-z ellipticals and dusty starbursts) [Daddi et al. 2000, 2001]

IRAC will sample low-mass stellar populations in high-z gals and measure baryonic mass to high-z (JHK become unreliable at z>1.5) z=2.5 z=1.27

The case of spirals galaxies z-distributions of Sp's in HDFN Evolutionary rate of Star-Formation Generation of stellar mass

Current situation about deep mid-IR surevys: few tens of square arcmins sampled by ISO to the relevant depths Elliptical galaxy in the HDF North ISO 6.7 μ

The case for SWIRE SIRTF will offer a unique chance to sample a largely unexplored waveband at 3 <λ<10 μm This will allow photometric measurements of the baryonic mass in stars for an enormous number of distant and high-z galaxies This is one of the main targets of our Legacy Program, SWIRE SWIRE will devote 500 hours to survey with IRAC a very large area (70 sq.deg.) to moderate depths (+ 400 hours with MIPS at longer-λ)

The SIRTF "SWIRE" Survey SIRTF Wide-area IR Extragalactic Survey, Legacy Programme (Lonsdale et al.), ~ 70 sq. deg. at all SIRTF photometric bands

ISO-selected IR starburst in the HDFS, template for SIRTF sources SWIRE/IRAC sensitivity limits ESIS limits M82 K=19.2 M51

SWIRE sensitivity ˜ K=21 for moderately red galaxies

Expected z-distributions in a 10 sq.deg. area sampled at the SWIRE flux limit Modelling the expected performances of SWIRE in the IRAC bands [model with z F =3]

Typical spectra

Photometric redshifts from purely the IRAC band fluxes

ISO-selected IR starburst in the HDFS, template for SIRTF sources SWIRE/IRAC sensitivity limits ESIS limits M82 K=19.2 M51

IRAC will sample low-mass stellar populations in high-z gals and measure baryonic mass to high-z (JHK become unreliable at z>1.5) z=2.5 z=1.27

CONCLUSIONS A dramatic step forward allowed by SWIRE in the investigation of both the "Active" and "Passive" Universe at high redshifts SWIRE will allow to match current sensitivity limits for the study of IR source populations (red type-II QSOs, starbursts, forming E/S0, passively evolving spheroids) on areas >100 times larger at λ's currently unaccessible