Dust attenuation, dust emission, and dust temperatures in z>5 galaxies A view from the FIRE cosmological simulations (arXiv:1902.10152) Xiangcheng Ma (Berkeley) [email protected]Dusting the Universe 03/05/2019 Collaborators: Caitlin Casey & the FIRE team
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Dust attenuation, dust emission, and dust temperatures in z>5 galaxies
A view from the FIRE cosmological simulations (arXiv:1902.10152)
Post-processing with SKIRT (Baes+2011; Camps+2015)
• SMC-like grain size distribution from Weingartner & Draine (2001)
• Constant dust-to-metal ratio (default 0.4; Dwek 1998) in <106 K gas
• Excluding CMB heating at the moment (cf. da Cunda+2013)
λ [μm]
F λ
UV
IR
Meurer+1999
Fλ ∼ λβ
IRX ≡ FIR/FUV
👀
Dust screen
Calzetti
SMC
Dust clumps
👀
The IRX–β relation:introduction
Ma+2019 (arXiv:1902.10152)
A tight IRX–β relation regardless of complex dust geometry
Increasing dust-to-metal ratio
FIRE z=0 sample
Ma+2019 (arXiv:1902.10152)
Dust temperature
Warmer dust in z>5 galaxies
Incre
asing
z
Ma+2019 (arXiv:1902.10152)
ALM
A B
and
6as
if a
t z =
6
ALMA—HUDF 1.2 mm deep survey
Aravena+16, Bouwens+16a, Dunlop+17
HST/WFC3: rest-frame UV
ALMA: dust continuum
Bouwens+2016 analysis
• The IRX–β relation: FUV→FIR
• 35 K-MBB SED: FIR→F1.2 mm
ALMA detected much fewer sources than expected at high z
See also e.g.Casey+18a
Why Tdust increases with z?
(A) (B)
(A) LIR ∼ MdustT6dust → Tdust ∼ ( LIR
Mdust )1/6
∼ sSFR1/6
Ma+2019 (arXiv:1902.10152)
(B) ⟨Σ⟩SFR ∼LIR
R2∼ Jν
∫∞
0κνJν dν = ∫
∞
0κνBν(Tdust) dν ∼ T6
dust
Moving into the future:• (Sub)mm surveys must go a few times deeper than they are now.• Wavelength coverage shorter than λpeak is required for LIR and Tdust.• JWST spectroscopy in rest-frame UV-optical ⇒ the extinction curve.Key questions to be answered:• Direct constraints and detections of obscured SF at z>5• Are dust properties in z>5 galaxies the same as z=0 or not?• Enrichment of dust and heavy elements in the early universe
Summary
The Chajnantor Sub/millimeter
Survey Telescope5.9-m diameter, 5−600 µm
• The bright-end UVLFs at z>5 require significant dust attenuation.• There is a tight IRX–β relation determined by the attenuation curve
despite of complex dust geometry.• Dust temperature (peak wavelength) increases (decreases) with z.