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Characterization of the mid- and far-IR population detected by ISO, Spitzer...
and HERSCHEL!!
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
10,000 1000 10 12 L ¤ Z = 0.1
100 10 1 0.1
0.5
1 3 5 10 100
(
m) 1,000 10,000 How?
After Guiderdoni et al. MNRAS 295, 877, 1998
• 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 < z < 1.0)
Wedding Cake Survey
Clusters GOODS-S 0.04 deg^2 GOODS-N 0.04 deg^2 GOODS-S/Groth/ Lockman 0.25 deg^2 Cosmos/XMM 2 deg^2 XMM/CDFS/Lockman 10 deg^2 ES1/EN1/EN2/XMM/ Lockman ... 50 deg^2 will probe L
bol
redshift range over a wide
Herschel Extragalactic GT Survey Wedding Cake Name Clusters Level 1 Level 2 Level 3 Level 4 Level 5 Level 6 Area deg^2 0.04
0.04
0.25
0.25
0.25
2 2 10 50 Field GOODS-S GOODS-N GOODS-S Groth Strip Lockman COSMOS XMM-LSS Spitzer Spitzer PACSTi me hr 80 230 27 34 34 34 110 110 185 SPIRE Time hr 100 10 + 30 10 25 25 25 50 50 200 150 70 mJy 1.0
2.0
2.2
2.2
2.2
6.0
18 18 18 110 mJy 1.0
2.8
6.2
6.2
6.2
9.8
9.8
16.9
170 mJy 1.0
3.0
6.7
6.7
6.7
10.5
10.5
18.0
120 250 mJy 3.3
6.7
10.5
10.5
10.5
21.1
21.1
23.6
61 350 mJy 500 mJy 4.0
8.1
12.7
12.7
12.7
25.5
25.5
28.5
74 4.6
9.2
14.5
14.5
14.5
29.1
29.1
32.5
84 Time : PACS (659) SPIRE (850) Harwit (10) (Spitzer Depths)
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
Redshift distributions
Better resolution!!
PACS Beam 4.74”@110um 110 micron / 3 mJy / 0.04 deg^2
Favourable K-corr!!
SPIRE Beam 24.4”@350um 350 micron / 9 mJy / 0.04 deg^2 Model by Franceschini 2008
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 environment, and determine clustering properties and
•
Determine the contribution of AGN
The Cosmic IR Background Radiation Resolved 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.
Lagache, Puget & Dole 2005 (ARAA)
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.
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
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 <1e12 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 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]
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
Far-IR & Sub-mm source counts
Vaccari et al in prep., Franceschini et al. in prep
SWIRE+GTO SWIRE+FLS CSO SHADES/SCUBA
Z=0-2.5 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
Constraining Bolometric Luminosity
Herschel bands at z=1 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.
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 z~2 obscured AGN activity (e.g. Daddi 2007, Fiore 2007 via stacking analysis).
1.4
° x1.4
° XMM COSMOS (Hasinger et al.)
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.
The power of multiwavelength studies ARP220 MKN231
Selection of massive high-z obscured AGN and starburst galaxies
Rodighiero et al. 2007
Extragalactic Confusion
Channel PACS1 PACS2 PACS3 SPIRE1 SPIRE2 SPIRE3
m Beam FWHM 3
[mJy] 4
[mJy] 5
[mJy] 10 bps [mJy] 70 4 .74” 0.0680
3 0.1962
0.3691
0.1100
110 6.96” 0.8979
2.073
3.454
1.263
170 10.76” 6.958
12.20
17.52
7.090
250 17.1” 18.26
27.89
37.38
14.00
350 24.4” 23.86
34.49
44.83
15.23
500 34.6” 22.16
31.03
39.57
13.23
20 bps
Due to the different slope in counts, the
[mJy] 0.3029
2.746
20.49
21.65
vs bps is not a one-to-one relation,
18.31
values
30 bps 0.4887
4.034
15.23
25.40
26.34
21.49
A Pre-Launch Consensus View on Herschel EG Confusion Limits
MEAN +- RMS of various models 4