Accurate simultaneous constraints on the dust mass, temperature, and emissivity index of a galaxy at redshift 7.31
Journal article, 2024
We present new multifrequency Atacama Large Millimeter/submillimeter Array (ALMA) continuum observations of the massive [ log 10 ( M∗ / M ⊙) = 10 . 3 + 0 . 1 -0. 2 ], UV-luminous [ M UV = -21 . 7 ±0 . 2] z = 7 . 31 galaxy REBELS-25 in Bands 3, 4, 5, and 9. Combining the new observations with previously taken data in Bands 6 and 8, we co v er the dust continuum emission of the galaxy in six distinct bands -spanning rest-frame 50 -350 μm -enabling simultaneous constraints on its dust mass ( M dust ), temperature ( T dust ), and emissivity index ( β IR ) via modified blackbody fitting. Given a fiducial model of optically thin emission, we infer a cold dust temperature of T dust = 32 + 9 -6 K and a high dust mass of log 10 ( M dust / M ⊙) = 8 . 2 + 0 . 6 -0 . 4 , and moderately optically thick dust does not significantly alter these estimates. If we assume dust production is solely through supernovae (SNe), the inferred dust yield would be high, y = 0 . 7 + 2 . 3 -0 . 4 M _per SN. Consequently, we argue grain growth in the interstellar medium of REBELS-25 also contributes to its dust build-up. This is supported by the steep dust emissivity index βIR = 2 . 5 ±0 . 4 we measure for REBELS-25, as well as by its high stellar mass, dense interstellar medium, and metal-rich nature. Our results suggest that constraining the dust emissivity indices of high-redshift galaxies is important not only to mitigate systematic uncertainties in their dust masses and obscured star formation rates, but also to assess if dust properties evolve across cosmic time. We present an efficient observing set-up to do so with ALMA, combining observations of the peak and Rayleigh-Jeans tail of the dust emission.
submillimetre: galaxies
galaxies: e volution
galaxies: high-redshift
Author
H. Algera
National Astronomical Observatory of Japan
Hiroshima University
H. Inami
Hiroshima University
I. De Looze
Ghent university
Andrea Ferrara
Scuola Normale Superiore di Pisa
Hiroyuki Hirashita
Osaka University
Academia Sinica
Manuel Aravena
Diego Portales University
Tom Bakx
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Rychard Bouwens
Leiden University
Rebecca A.A. Bowler
University of Manchester
E. da Cunha
ARC Centre of Excellence for All-sky Astrophysics
University of Western Australia
Pratika Dayal
University of Groningen
Yoshinobu Fudamoto
National Astronomical Observatory of Japan
Waseda University
J. Hodge
Leiden University
Alexander Hygate
Leiden University
Ivana van Leeuwen
Leiden University
Themiya Nanayakkara
Swinburne University of Technology
Marco Palla
Ghent university
Istituto nazionale di astrofisica (INAF)
Andrea Pallottini
Scuola Normale Superiore di Pisa
Lucie Rowland
Leiden University
Renske Smit
Liverpool John Moores University
Laura Sommovigo
Flatiron Institute
Mauro Stefanon
Universitat de Valencia
A. P. Vijayan
Technical University of Denmark (DTU)
Cosmic Dawn Center (DAWN)
P. van der Werf
Leiden University
Monthly Notices of the Royal Astronomical Society
00358711 (ISSN) 13652966 (eISSN)
Vol. 533 3 3098-3113Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stae1994