A warm ultraluminous infrared galaxy just 600 million years after the big bang

ABSTRACT We present an Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 continuum detection ($3.3 \sigma$) of MACS0416_Y1 that confirms the suspected warm dust (91$^{+62}_{-35}$ K) of this Lyman-Break Galaxy (LBG) at $z = 8.3$ with $\log _{10} M_{\ast }/$M$_{\odot } = 9.0 \pm 0.1$. A modified blackbody fit to the ALMA Bands 3 through 9 data of MACS0416_Y1 finds an intrinsic infrared luminosity of 1.0$^{+1.8}_{-0.6} \times {} 10^{12}\ \mathrm{L_{\odot }}$, placing this UV-selected LBG in the regime of Ultra Luminous Infrared Galaxies. Its luminous but modest dust reservoir (1.4$^{+1.3}_{-0.5} \times {} 10^{6}\ \mathrm{{\rm M}_{\odot }}$) is cospatial to regions with a UV-continuum slope $\beta _{\rm UV} \approx -1.5$ as seen by James Webb Space Telescope (JWST) imaging. Although this implies some dust obscuration, the JWST photometry implies less obscured star formation than seen in the complete characterization by ALMA, implying some spatial separation of dust and stars on scales below 200 pc, i.e. smaller than those probed by JWST and ALMA. This source is an extreme example of dust-obscured star formation contributing strongly to the cosmic build-up of stellar mass, which can only be revealed through direct and comprehensive observations in the (sub)mm regime.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-11-10
DOI
https://doi.org/10.1093/mnras/staf1714
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

A warm ultraluminous infrared galaxy just 600 million years after the big bang

Juan Molina, A. Pallottini, Gunnar Nyman, Bunyo Hatsukade et al.
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
article

A warm ultraluminous infrared galaxy just 600 million years after the big bang

Juan Molina, A. Pallottini, Gunnar Nyman, Bunyo Hatsukade, Duncan Bossion, Yoichi Tamura, Nicolas Laporte, Stefano Carniani, S. Aalto, K. K. Knudsen, Ken Mawatari, Hanae Inami, Takuya Hashimoto, Andrea Ferrara, Hiddo Algera, Takashi Okamoto, Hideki Umehata, Akio Inoue, Naoki Yoshida, Renske Smit, Laura Sommovigo, Clarke J. Esmerian, Masato Hagimoto, W. M. C. Sameera, Tom J. L. C. Bakx, E. Ibar, W. H. T. Vlemmings
article en

Abstract

ABSTRACT We present an Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 continuum detection ($3.3 \sigma$) of MACS0416_Y1 that confirms the suspected warm dust (91$^{+62}_{-35}$ K) of this Lyman-Break Galaxy (LBG) at $z = 8.3$ with $\log _{10} M_{\ast }/$M$_{\odot } = 9.0 \pm 0.1$. A modified blackbody fit to the ALMA Bands 3 through 9 data of MACS0416_Y1 finds an intrinsic infrared luminosity of 1.0$^{+1.8}_{-0.6} \times {} 10^{12}\ \mathrm{L_{\odot }}$, placing this UV-selected LBG in the regime of Ultra Luminous Infrared Galaxies. Its luminous but modest dust reservoir (1.4$^{+1.3}_{-0.5} \times {} 10^{6}\ \mathrm{{\rm M}_{\odot }}$) is cospatial to regions with a UV-continuum slope $\beta _{\rm UV} \approx -1.5$ as seen by James Webb Space Telescope (JWST) imaging. Although this implies some dust obscuration, the JWST photometry implies less obscured star formation than seen in the complete characterization by ALMA, implying some spatial separation of dust and stars on scales below 200 pc, i.e. smaller than those probed by JWST and ALMA. This source is an extreme example of dust-obscured star formation contributing strongly to the cosmic build-up of stellar mass, which can only be revealed through direct and comprehensive observations in the (sub)mm regime.

Monthly Notices of the Royal Astronomical SocietyVol. 544(2)
Hiroshima University (JP), Centre National de la Recherche Scientifique (FR), Institute of Astronomy and Astrophysics, Academia Sinica (TW), University of Tsukuba (JP), Waseda University (JP), Scuola Normale Superiore (IT), The Graduate University for Advanced Studies, SOKENDAI (JP), Hokkaido University (JP), Université Rennes 2 (FR), Laboratoire d’Astrophysique de Marseille (FR), Institut de Physique de Rennes (FR), Institute of Astronomy (RU), Institut de génétique et de développement de Rennes (FR), Flatiron Health (United States) (US), Millenium Nucleus for Planet Formation (CL), National Astronomical Observatory of Japan (JP), Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (IT), Université de Rennes (FR), Nagoya University (JP), Liverpool John Moores University (GB), Chalmers University of Technology (SE), The University of Tokyo (JP), University of Valparaíso (CL), University of Gothenburg (SE)
Openalex Percentile: Top 77%
Galaxies: Formation, Evolution, Phenomena
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