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Published October 2019 | Published + Submitted
Journal Article Open

On the dust temperatures of high redshift galaxies


Dust temperature is an important property of the interstellar medium (ISM) of galaxies. It is required when converting (sub)millimetre broad-band flux to total infrared luminosity (L_(IR)), and hence star formation rate, in high-redshift galaxies. However, different definitions of dust temperatures have been used in the literature, leading to different physical interpretations of how ISM conditions change with, e.g. redshift and star formation rate. In this paper, we analyse the dust temperatures of massive (⁠M_(star) > 10¹⁰M⊙⁠) z = 2–6 galaxies with the help of high-resolution cosmological simulations from the Feedback in Realistic Environments (FIRE) project. At z ∼ 2, our simulations successfully predict dust temperatures in good agreement with observations. We find that dust temperatures based on the peak emission wavelength increase with redshift, in line with the higher star formation activity at higher redshift, and are strongly correlated with the specific star formation rate. In contrast, the mass-weighted dust temperature, which is required to accurately estimate the total dust mass, does not strongly evolve with redshift over z = 2–6 at fixed IR luminosity but is tightly correlated with LIR at fixed z⁠. We also analyse an 'equivalent' dust temperature for converting (sub)millimetre flux density to total IR luminosity, and provide a fitting formula as a function of redshift and dust-to-metal ratio. We find that galaxies of higher equivalent (or higher peak) dust temperature ('warmer dust') do not necessarily have higher mass-weighted temperatures. A 'two-phase' picture for interstellar dust can explain the different scaling relations of the various dust temperatures.

Additional Information

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 July 30. Received 2019 July 17; in original form 2019 March 12. Published: 02 August 2019. We are grateful to the referee for the careful review and insightful suggestions that have helped improve the quality of this manuscript. We acknowledge the comments from Andreas Faisst, Rob Ivison, Allison Kirkpatrick, Georgios Magdis, and Ian Smail to an early draft. We thank Caitlin Casey for a discussion on Casey et al. (2018a,b) before they were published on arXiv, which had helped the writing of this paper. We are grateful to the technical guidance by Peter Camps and Maarten Baes. LL would like to acknowledge the stimulating atmosphere during the Munich Institute for Astro- and Particle Physics (MIAPP) 2018 programme The Interstellar Medium of High Redshift Galaxies, and especially thank the conversation with the programme coordinators. This research was supported by the MIAPP of the Deutsche Forschungsgemeinschaft (DFG) cluster of excellence 'Origin and Structure of the Universe'. RF acknowledges financial support from the Swiss National Science Foundation (grant no. 157591). Simulations were run with resources provided by the NASA High-End Computing (HEC) Programme through the NASA Advanced Supercomputing (NAS) Division at Ames Research centre, proposal SMD-14-5492. Additional computing support was provided by HEC allocations SMD-14-5189, SMD-15-5950, by NSF XSEDE allocations AST120025, AST150045, by allocations s697, s698 at the Swiss National Supercomputing Centre (CSCS), and by S3IT resources at the University of Zurich. DK acknowledges support from the NSF grant AST-1715101 and the Cottrell Scholar Award from the Research Corporation for Science Advancement. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522; by NASA through grant 17-ATP17-0067; by STScI through grant HST-AR-14562.001; and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. PFH was supported by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. EQ was supported in part by a Simons Investigator Award from the Simons Foundation and by NSF grant AST-1715070. The Flatiron Institute is supported by the Simons Foundation.

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Submitted - 1902.10727.pdf


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August 19, 2023
October 18, 2023