Download A Physical Model for the Anisotropies of Cosmic Far-infrared Background

A Physical Model for the Anisotropies of
Cosmic Far-infrared Background
Heidi Wu (Caltech)
with Olivier Doré and Romain Teyssier
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Cosmic Far-Infrared Background
Dole+06
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Spectral Energy Distribution of Galaxies
UV
Near-IR
Far-IR
Conroy 13
Dust SED peaks at ~ 100 !m (3000 GHz)
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Angular Power Spectrum of CIB
Planck early results. XVIII.
Planck HFI: 217, 353, 545, 857 GHz (350-1400 !m)
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Can we interpret CIB power spectra
using a physical model of galaxies?
Lilly+13
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The Gas Regulator (Bathtub) Model
(Bouché+10, Lilly+13, Dekel+14, Peng+14, Feldmann15, etc.)
Treating a galaxy as a reservoir of gas with
1. sources (cosmic accretion)
2. sinks (stars)
3. ejection (stellar feedback, wind)
and solving the continuity equations for gas, stars, and metals.
Such a system is self-regulating because the consumption rate
(SF) is proportional to the supply rate (gas). The system will
reach a quasi steady-state solution.
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Summary of Our Model
• Gas accretion rate ∝ dark matter accretion rate
• Feedback and gas ejection (see the next slide)
• Star formation rate (SFR) = Mgas/tsf
• LIR = SFR/K (Kennicutt 98)
• Mdust ∝ metal mass
• SED ∝νβ B(Tdust)
• Tdust: based on thermal equilibrium
• The analytic halo model => CIB power spectra
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Star-formation efficiency peaks at
Mhalo~1012M⊙
Quenching/
AGN feedback
Mstar/Mhalo
Stellar/SN
feedback
Mhalo [M⊙]
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Behroozi+13
Modeling the Mass Loading Factor
Def: η =
mass ejection rate
star formation rate
η
M-α1
Mα2
Less gas is available
for both low- and
high-mass halos
η0
M
Mpk
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Looking for the best-fit model
• Six free parameters:
‣
normalization and 2 slopes for the mass loading factor
‣
redshift evolution of accretion rate
‣
scatter of LIR given Mhalo
‣
spectral index of the modified blackbody
• Data sets:
‣
CIB power spectra from Planck 2013 results XXX
‣
absolute CIB intensity from COBE-FIRAS
‣
FIR luminosity function from Herschel, Spitzer (z<4)
• MCMC sampling with emcee (Foreman-Mackey+13)
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The Best-fit Model: CIB Power Spectrum
Similar for 353, 545, 857
GHz (auto and cross
spectra)
1-halo term is subdominant
11
Wu et al. (in prep)
The Best-fit Model: FIR Luminosity Function
Similar for other 0 <z < 4
data.
~80% scatter of LIR at a
given Mhalo is required to
fit the bright-end
12
Wu et al. (in prep)
Implication: LIR-Mhalo Relation
• Comparing with
Behroozi 13 SFR,
assuming LIR = SFR/K
• Massive halos: LIR
higher than expected
from SFR. Dust-obscured
AGNs or mergers?
• Low-mass halos: LIR
slightly lower than
expected from SFR. LIR SFR relation depends on
mass?
13
Wu et al. (in prep)
Implication: Effective Bias
Consistent with:
• Mhalo = 1013 M⊙ at z = 0
• Mhalo = 1012.5 M⊙ at z = 2
Possible selection bias:
FIR galaxies might live in
crowded environments
14
Wu et al. (in prep)
Implication: Dust Properties
• The non-monotonic
scaling is due to the
feedback.
• Consistent with
Magnelli 12 results from
Herschel (selected from
ground-based submm
telescopes)
15
Wu et al. (in prep)
Implication: Dust Properties
• Data: Magnelli 12
results from Herschel
(selected in submm)
• Submm selection tends
to select low dust
temperature
16
Wu et al. (in prep)
Cosmic Star-formation History
• Comparing with recent
UV and IR compilation of
Madau & Dickinson 14
• z<2: slightly lower than
UV/IR results
• The z-dependence is
associated with the dark
matter accretion rate.
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Wu et al. (in prep)
Cosmic Dust Density
• Consistent with
- Thacker 13 from Herschel
CIB
- Dunne 11 from Herschel
Luminosity Function
• Menard & Fukugita 12
from MgII absorber
provides lower limit
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Wu et al. (in prep)
Chajnantor Submm Survey Telescope (CSST)
• PI: Sunil Golwala
• Goal: finding all galaxies with
SFR > 100 M⊙/yr
• 30m telescope surveying with
850!m, 7” resolution
• 1 deg FoV, covering ~1000
deg2 ~107 galaxies per year
• Photo-z from LSST/Euclid
• SFR-M relation from the
clustering of galaxies
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Summary
• We apply the gas regulator model to calculate the
star formation rate and the dust mass of galaxies,
and use the halo model to calculate the CIB power
spectra.
• The best-fit model indicates that
‣
CIB is dominated by halos of 1012.5-13 M⊙
‣
LIR from massive halos are high compared with
optical SFR expectation
‣
ρSFR and &dust are consistent with other
observations
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