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...digerendo la pizza...
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Characterization of the mid- and far-IR
population detected by ISO, Spitzer... and
HERSCHEL!!
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High-z GT Programme
Herschel probes the rest-frame bolometric
emission from galaxies as they formed most of
their stars
Will address issues like
History of star formation and energy
production Structure formation Cluster
evolution CIRB fluctuations AGN-starburst
connection
How?
Investing 850hrs of SPIRE (Hermes) and 650hrs
of PACS (PEP) GT Observing a Set of Blank
Fields in Different Depths Observing a Sample
of Rich Clusters (0.2 lt z lt 1.0)
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Wedding Cake Survey
will probe Lbol over a wide redshift range
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Herschel Extragalactic GT Survey Wedding Cake
Time PACS (659) SPIRE (850) Harwit (10)
(Spitzer Depths)
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The case for a joint effort

• PACS strengths
• Excellent spatial resolution
• Capabilities for FIR spectroscopy of selected
  subsamples
• SPIRE strengths
• Best exploitation of K-correction for high-z
  sources
• Fast mapping speed
• Both are needed for characterizing FIR/sub-mm
  properties of large samples of high-z objects

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Redshift distributions
Favourable K-corr!!
Better resolution!!
SPIRE
PACS
Beam 24.4_at_350um 350 micron / 9 mJy / 0.04 deg2
Beam 4.74_at_110um 110 micron / 3 mJy / 0.04 deg2
Model by Franceschini 2008
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PEP

the PACS Evolutionary Probe is a Herschel
guaranteed time key programme survey of the
extragalactic sky, aimed to study the restframe
far-infrared emission of galaxies up to redshift
3, as a function of environment. The survey
will shed new light on the constituents of the
cosmic IR background and their nature, as well as
on the co-evolution of AGN and starbursts. PEP is
coordinated with SPIRE GT observations of the
same fields in the HerMES program.
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• GT (PEP HERMES) SCIENCE GOALS
• Resolve the Cosmic Infrared Background and
  determine the nature of its constituents.
• Determine the cosmic evolution of dusty star
  formation and of the infrared luminosity function
• Elucidate the relation of far-infrared emission
  and environment, and determine clustering
  properties
• Determine the contribution of AGN

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The Cosmic IR Background RadiationResolved Into
Sources
The integrated extragalactic background light in
the far-infrared and sub-millimeter region of the
spectrum is approximately equal to the integrated
background light in the optical and UV part of
the spectrum. To develop a complete
understanding of galaxy formation, this
background light must be resolved into galaxies
and their properties must be characterized.
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The power of multiwavelength studies
IRAC/SPITZER 3.6-8.0 micron passive massive
stellar dominated galaxies star forming
sources MIPS/SPITZER 24/70/160 micron SF
dominated galaxies, LIRGs, ULIRGS, emission
dominated by dust reprocessed UV/optical
photons HERSCHEL 70-500 micron detect the peak
of the bolometric IR emission
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Lagache, Puget Dole 2005 (ARAA)
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One of the most direct results of deep PACS
surveys will be the resolution of the majority of
the CIB into individual well detected sources, at
wavelengths near the CIB peak which contains most
of the energy and represents most of the cosmic
star formation and metal production, modulo the
contribution of AGN. We expect to resolve about
80, 85 and 55 of the CIB due to galaxies at
75, 110, and 170 microns into individual 5-sigma
detected sources for the blank field surveys.
These fractions clearly depend on the faint
number counts at these wavelengths that only PACS
can measure. Lensing cluster observations and
fluctuation analysis will increase these
fractions further. Using the wealth of
multi-wavelength data already existing in the
chosen well-studied fields and techniques like
SED fitting, as well as dedicated follow up
projects, we will be able to determine the
physical nature of these objects, for example
redshifts, luminosities, morphologies, masses,
star formation histories, and the role of AGN
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We expect to resolve about 80, 85 and 55 of
the CIB due to galaxies at 75, 110, and 170
microns into individual 5-sigma detected sources
for the blank field surveys. These fractions
clearly depend on the faint number counts at
these wavelengths that only PACS can measure.
Using the wealth of multi-wavelength data
already existing in the chosen well-studied
fields and techniques like SED fitting, as well
as dedicated follow up projects, we will be able
to determine the physical nature of these
objects, for example redshifts, luminosities,
morphologies, masses, star formation histories,
and the role of AGN.
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How does the star formation rate density and
galaxy luminosity function evolve?
Luminosity of infrared galaxies detectable in the
three PACS bands at different redshifts for a
single star-forming SED galaxy
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Our surveys will sample the critical far-infrared
peak of star forming galaxy SEDs and will probe a
large part of the infrared luminosity function,
down to luminosities of 1e11 Lsun at redshift 1
and lt1e12 Lsun at redshift 2. This will enable a
detailed study of the evolution of the infrared
luminosity function with redshift, expanding on
the results based on mid-infrared or submm
surveys and suppressing the associated
uncertainties due to extrapolation of the IR
SEDs. The the multi-wavelength coverage of our
fields will ensure a robust estimate of
photometric stellar masses, hence extending
studies of the evolution of the specific star
formation rate to the currently missing obscured
component of star formation.
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The PEP surveys will sample the critical
far-infrared peak of star forming galaxy SEDs and
will probe a large part of the infrared
luminosity function, down to luminosities of
1e11 Lsun at redshift 1 and lt1e12 Lsun at
redshift 2. This will enable a detailed study
of the evolution of the infrared luminosity
function with redshift, expanding on the results
based on mid-infrared or submm surveys and
suppressing the associated uncertainties due to
extrapolation of the IR SEDs.
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The Padova IR evolutionary model (Franceschini
et al. 2008, in prep.)

• The 2001 phenomenological model (Franceschini et
  al. 2001) was rather successful in explaining
  exploring ISO results
• Spitzer SCUBA data (re)-analyses, however,
  called for a revamp
• Through a simple backward evolution approach,
  FR08 describes available observables (number
  counts, z-distributions, L-functions, integrated
  CIRB levels) in terms of number and luminosity
  evolution of four populations
• slowly or non-evolving disk galaxies blue dotted
  lines
• type-1 AGNs evolving as shown by UV and X-ray
  selected Quasars Seyferts green long-short
  dashed lines
• moderate-luminosity starbursts with peak emission
  at z 1 cyan dot-dashed lines
• ultra-luminous starbursts with peak evolution
  between z 2 and z 4 red long dashed lines

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Modeling Benchmarks
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Spitzer MIPS Counts redshift distribution 24
?m

• Most stringent constraint
• provided by Spitzer to date

Vaccari et al 2008, Rodighiero et al 2008 in prep
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Far-IR Sub-mm source counts
Vaccari et al in prep., Franceschini et al. in
prep
SWIREFLS
SWIREGTO
CSO
SHADES/SCUBA
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Z0-2.5 24 ?m Luminosity Functions

• GOODS-S GOODS-N SWIRE-VVDS Fields (Rodighiero
  et al. 2008 in prep)
• 2000 sources with some of the best spec info
  available

The determination of redshift-dependent
Luminosity Functions require large corrections
which depend to a large extent on the adopted SED
templates, and particularly so for IR Bolometric
(8-1000 ?m) Luminosity Functions
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Constraining Bolometric Luminosity
Herschel bands at z1 vs model spectra
Herschel bands will be crucial in constraining
the bolometric luminosity of galaxies. This will
help untangle the contribution of AGN and
star-formation cool/warm dust and thus constrain
the star-formation history.
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What is the role of AGN and how do they co-evolve
with galaxies?

Recent combined X-ray and Spitzer surveys have
revised our view of the history of accretion onto
AGN, in particular with respect to the detection
of high redshift z2 obscured AGN activity (e.g.
Daddi 2007, Fiore 2007 via stacking analysis).

• 1.4x1.4 XMM COSMOS (Hasinger et al.)

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The close relation in the local universe between
black hole mass and bulge properties calls for
studies of how AGN and galaxies co-evolve.
According to recent models, feedback by AGN is
also central to terminating star formation in
massive galaxies (Croton et al. 2006). Both
locally and at high redshift, many infrared
galaxies host both star formation and an active
nucleus (e.g. Genzel et al. 1998, Alexander et
al. 2003, 2005, Valiante et al. 2007). The PEP
survey will shed new light on this relation, as a
function of redshift and of galaxy properties, by
studying for significant AGN samples the rest
frame far-infrared emission and its relation to
the AGN properties. Recent X-ray and optical
surveys have revised our view of the history of
accretion onto AGN, in particular with respect to
the surprising role of moderate redshift z0.5-1
obscured AGN (e.g. Hasinger 2003, Brandt
Hasinger 2005). PEP will also probe the
far-infrared emission of fully obscured AGN not
detected in X-ray surveys. Recent Spitzer mid-IR
surveys detected a significant population of
obscured AGNs, not accounted for by traditional
optical or X-ray selections (e.g. Donley et al.
2005, Lutz et al. 2005, Martinez-Sansigre et al.
2005). In combination with SPIRE, and Spitzer 24
microns data, PEP/PACS will determine the overall
SEDs of active galaxies, including AGN mid-IR
emission. Hence PEP will quantify the total
energetics of the obscured phases in black-hole
evolution, as well as of the associated star
formation.
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PEP will also probe the far-infrared emission of
fully obscured AGN not detected in X-ray surveys.
Recent Spitzer mid-IR surveys detected a
significant population of obscured AGNs, not
accounted for by traditional optical or X-ray
selections (e.g. Donley et al. 2005, Lutz et al.
2005, Martinez-Sansigre et al. 2005). In
combination with SPIRE, and Spitzer 24 microns
data, PEP/PACS will determine the overall SEDs of
active galaxies, including AGN mid-IR emission.
Hence PEP will quantify the total energetics of
the obscured phases in black-hole evolution, as
well as of the associated star formation.
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The power of multiwavelength studies
MKN231
ARP220
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Selection of massive high-z obscured AGN and
starburst galaxies
Rodighiero et al. 2007
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!! time for a coffee !!
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Extragalactic Confusion
Channel PACS1 PACS2 PACS3 SPIRE1 SPIRE2 SPIRE3
?m 70 110 170 250 350 500
Beam FWHM 4 .74 6.96 10.76 17.1 24.4 34.6
3 ? mJy 0.06803 0.8979 6.958 18.26 23.86 22.16
4 ? mJy 0.1962 2.073 12.20 27.89 34.49 31.03
5 ? mJy 0.3691 3.454 17.52 37.38 44.83 39.57
10 bps mJy 0.1100 1.263 7.090 14.00 15.23 13.23
20 bps mJy 0.3029 2.746 11.82 20.49 21.65 18.31
30 bps mJy 0.4887 4.034 15.23 25.40 26.34 21.49
40 bps mJy 0.6656 5.110 18.12 29.18 29.93 24.09
50 bps mJy 0.8350 6.107 20.45 32.47 33.05 26.18
Due to the different slope in counts, the ? vs
bps is not a one-to-one relation, ? values being
generally consistently worse than bps ones for
SPIRE with respect to PACS
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A Pre-Launch Consensus Viewon Herschel EG
Confusion Limits
MEAN - RMS of various models4 ? values above
are arguablybest pre-launch indication