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

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SWIRE view on the "Passive Universe"Studying
the evolutionary mass function and clustering of
galaxies with the SIRTF Wide-Area IR
Extragalactic Survey (SWIRE)
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Formation of massive ellipticals, S0s
and galaxy spheroids
Formation of large disks
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- 100
- 10
log ?(gtz)
- 1
The cumulative Stellar Mass Density vs. Star
Formation Rate
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z1.27
1 Gyr
3 Gyr
5 Gyr
7 Gyr
t9 Gyr
Photometric estimates of the stellar mass in
high-z galaxies
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Current situation about the origin of spheroidal
galaxies and the evolution of the galaxy mass
function (at 1ltzlt2) is very complex, uncertain,
and subject to a hot debate
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MASSES of E/S0 galaxies in the HDFs vs.
redshift (Rodighiero, Franceschini Fasano 2001)
Sample of 69 E/S0's to K20.2 morphologically
selected over 11 sq.arcmin in HDFN, HDFS NICMOS
Dotted Model 1 Continuous Model 2
Salpeter IMF with 0.15ltMlt100 Mo
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Redshift distribution for E/S0 in the HDFs
NICMOS vs. predictions for different zF
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Model 1
Typical SEDs of morphologically- classified E/S0
galaxies
Model 2
Franceschini et al. (1998)
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Rest-frame colours for early-type galaxies
compared with model SSPs
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Passive Ellipticals
Dusty Starbursts
Sample of 45 ERO's selected Klt19.2 over 52
sq.arcmin (Cimatti et al. 2001)
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Moriondo et al. (2000) study of Extremely Red
Objects selected in K
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Stanford et al. (1998)
"Colors of high-z cluster galaxies"
Solid line zF5, dashed line zF2
Evidence for a different star-formation history
in high-density environments accelerated with
cosmic time wrt. the field?
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Spatial clustering of EROs (high-z ellipticals
and dusty starbursts) Daddi et al. 2000, 2001
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z1.27
z2.5
IRAC will sample low-mass stellar populations in
high-z gals and measure baryonic mass to high-z
(JHK become unreliable at zgt1.5)
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z-distributions of Sp's in HDFN
Evolutionary rate of Star-Formation
The case of spirals galaxies
Generation of stellar mass
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ISO 6.7 µ
Elliptical galaxy in the HDF North
Current situation about deep mid-IR surevys few
tens of square arcmins sampled by ISO to the
relevant depths
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The case for SWIRE

• SIRTF will offer a unique chance to sample a
  largely unexplored waveband at 3 lt?lt10 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-?)

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The SIRTF "SWIRE" Survey
SIRTF Wide-area IR Extragalactic Survey, Legacy
Programme (Lonsdale et al.), 70 sq. deg. at
all SIRTF photometric bands
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M82
M51
K19.2
SWIRE/IRAC sensitivity limits
ESIS limits
ISO-selected IR starburst in the HDFS, template
for SIRTF sources
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SWIRE sensitivity K21 for
moderately red galaxies
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Modelling the expected performances of SWIRE in
the IRAC bands model with zF3
Expected z-distributions in a 10 sq.deg. area
sampled at the SWIRE flux limit
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Typical spectra
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Photometric redshifts from purely the IRAC band
fluxes
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M82
M51
K19.2
SWIRE/IRAC sensitivity limits
ESIS limits
ISO-selected IR starburst in the HDFS, template
for SIRTF sources
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z1.27
z2.5
IRAC will sample low-mass stellar populations in
high-z gals and measure baryonic mass to high-z
(JHK become unreliable at zgt1.5)
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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 gt100 times
  larger at ?'s currently unaccessible