Collaborators: Lee Armus, Danny Dale, Tanio Diaz-Santos, Chris - - PowerPoint PPT Presentation

Collaborators: Lee Armus, Danny Dale, Tanio Diaz-Santos, Chris Hayward, Alex Pope, Anna Sajina, Dave Sanders, Rachel Somerville, Sabrina Stierwalt

• Peak of the far-IR becomes warmer

with LIR

• LIR and dust temperature are

correlated

• Can infer Tdust from LIR alone
• Locally, IR SED is parameterized by LIR
• PAH emission decreases with LIR
• In the past, this picture was applied to

high redshift galaxies

Casey et al. (2012)

Casey et al. (2012) Kirkpatrick et al. (2012) Sajina et al. (2012)

Larson et al. (2016) Larson et al. (2016) Rujopakarn et al. (2011)

Rujopakarn et al. (2016)

log LIR log LPAH / LIR

Kirkpatrick et al. (2014b) Rujopakarn et al. (2011)

IRSA/IPAC Kirkpatrick et al. (2017)

• 5 mJy Unbiased Spitzer Extragalactic

Survey (PI George Helou)

• Select SF galaxies with Spitzer IRS

spectra

• z = 0.05 - 0.75
• LIR > 1010 Lsun
• 30 SF galaxies with Herschel 500 μm
• bservations
• Great Observatories All-sky LIRG

Survey (PI Lee Armus & Dave Sanders)

• Select SF galaxies with Spitzer IRS

spectra; also remove double nuclei

• z < 0.088
• 46 galaxies have 850 μm imaging

Kirkpatrick et al. (2017) Kirkpatrick et al. (2017)

• Use L160/L70 to approximate Tdust, since

this is model-independent

• Observe the expected shift in L160/L70

with LIR

• A few 5MUSES sources are more like

high z sample

• Technique (ala Scoville+16):
• Only use submm fluxes where λrest > 250 μm
• Assume T = 25 K
• Use variable 𝛌 from Weingartner & Draine

(2001)

• High z galaxies have factor of 5

higher dust mass

• Correlation between LIR/Mdust and

LIR-> normalization evolves with redshift

• Convert Mdust into MH2 using

Scoville+16 relationship

• At z=1-2, dusty galaxies are less

efficient at forming stars

Mdust = SνDL κνBν(T)

Kirkpatrick et al. (2017)

Kirkpatrick et al. (2017)

• LIR / Mdust ∝ interstellar

radiation field

• Interstellar radiation field

drives Tdust

• Seen on smaller scales in

local galaxies

• If global galaxy emission is a

single temperature blackbody -> correlation is expected

Kirkpatrick et al. (2014a) SFR/Mdust Tdust

Kirkpatrick et al. (2017)

• LIR / Mdust ∝ interstellar

radiation field

• Interstellar radiation field

drives Tdust

• Seen on smaller scales in

local galaxies

• If global galaxy emission is a

single temperature blackbody -> correlation is expected

• Any change in size

(compact, extended) might be a second order effect

Sizes from gas/radio in Rujopakarn+11

Misselt et al. (2001)

• Far-IR should contain information about

geometry and size of the ISM

• Is the structure of the ISM different

with redshift?

• Can the structure of the ISM account

for scatter and slope?

Simple model: LIR / Mdust ∝T4+β

Mdust(M)

Z = 1.2 Z = 0.0

M⇤(M)

fgas

0.0 0.5 1.0 1.5

z

• 1. fgas = 0.1*(1+z)2 (Geach+11)
• 2. For M* = 10.7 Msun, calculate MH2
• 3. Convert MH2 to Mdust, assuming D/G = 100

Kirkpatrick et al. (2014b)

Kirkpatrick et al. (2017)

Kirkpatrick et al. (2017)

• Open issues
• What redshift do galaxy relationships change?
• Can we learn about the structure of the ISM from global far-IR

measurements?

• What is the physical extent of the dusty ISM in high z DSFGs?
• Evolution in grain composition?

• L160 / L70 traces the peak of the SED
• L250 / L70 traces the relative

importance of cold dust

• Colors parameterized by

dMdust ∝ U𝛃 dU (Dale+2014)

• For a given L160/L70, high z sources

have higher L250/L70

• More submm emission = higher dust

masses?

Kirkpatrick et al. (2017) Kirkpatrick et al. (2017)