Collaborators: Lee Armus, Danny Dale, Tanio Diaz-Santos, Chris Hayward, Alex Pope, Anna Sajina, Dave Sanders, Rachel Somerville, Sabrina Stierwalt
• Locally, IR SED is parameterized by L IR • PAH emission decreases with L IR • In the past, this picture was applied to high redshift galaxies • Peak of the far-IR becomes warmer with L IR • L IR and dust temperature are correlated • Can infer T dust from L IR alone Casey et al. (2012)
Kirkpatrick et al. (2012) Sajina et al. (2012) Casey et al. (2012)
Larson et al. (2016) Larson et al. (2016) Rujopakarn et al. (2011)
log L PAH / L IR log L IR Kirkpatrick et al. (2014b) Rujopakarn et al. (2016) Rujopakarn et al. (2011)
IRSA/IPAC Kirkpatrick et al. (2017)
• Great Observatories All-sky LIRG • 5 mJy Unbiased Spitzer Extragalactic Survey (PI Lee Armus & Dave Survey (PI George Helou) Sanders) • Select SF galaxies with Spitzer IRS • Select SF galaxies with Spitzer IRS spectra spectra; also remove double nuclei • z = 0.05 - 0.75 • z < 0.088 • L IR > 10 10 L sun • 46 galaxies have 850 μm imaging • 30 SF galaxies with Herschel 500 μm observations
Kirkpatrick et al. (2017) • Use L 160 /L 70 to approximate T dust , since this is model-independent • Observe the expected shift in L 160 /L 70 with L IR • A few 5MUSES sources are more like high z sample Kirkpatrick et al. (2017)
• Technique (ala Scoville+16): • Only use submm fluxes where λ rest > 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 L IR /M dust and L IR -> normalization evolves with redshift • Convert M dust into M H2 using Scoville+16 relationship • At z =1-2, dusty galaxies are less Kirkpatrick et al. (2017) efficient at forming stars S ν D L M dust = κ ν B ν ( T )
• L IR / M dust ∝ interstellar radiation field • Interstellar radiation field drives T dust • Seen on smaller scales in local galaxies • If global galaxy emission is a single temperature blackbody -> correlation is Kirkpatrick et al. (2017) expected T dust SFR/M dust Kirkpatrick et al. (2014a)
• L IR / M dust ∝ interstellar radiation field • Interstellar radiation field drives T dust • Seen on smaller scales in local galaxies • If global galaxy emission is a single temperature blackbody -> correlation is Kirkpatrick et al. (2017) expected • Any change in size Sizes from gas/radio in (compact, extended) might Rujopakarn+11 be a second order effect
Simple model: L IR / M dust ∝ T 4+β • 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? Misselt et al. (2001)
Z = 1.2 M dust ( M � ) Z = 0.0 f gas M ⇤ ( M � ) Kirkpatrick et al. (2017) 1. f gas = 0.1*(1+z) 2 (Geach+11) 2. For M * = 10.7 M sun , calculate M H2 3. Convert M H2 to M dust , assuming D/G = 100 0.0 0.5 1.0 1.5 z Kirkpatrick et al. (2014b)
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?
Kirkpatrick et al. (2017) • L 160 / L 70 traces the peak of the SED Kirkpatrick et al. (2017) • For a given L 160 /L 70 , high z sources • L 250 / L 70 traces the relative have higher L 250 /L 70 importance of cold dust • More submm emission = higher dust • Colors parameterized by masses? dM dust ∝ U 𝛃 dU (Dale+2014)
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