ALMA uncovers the [C ii] emission and warm dust continuum in a z = 8.31 Lyman break galaxy

ABSTRACT We report on the detection of the [C ii] 157.7 μm emission from the Lyman break galaxy (LBG) MACS0416_Y1 at z = 8.3113, by using the Atacama Large Millimeter/submillimeter Array (ALMA). The luminosity ratio of [O iii] 88 μm (from previous campaigns) to [C ii] is 9.3 ± 2.6, indicative of har...

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Veröffentlicht in:Monthly notices of the Royal Astronomical Society Jg. 493; H. 3; S. 4294 - 4307
Hauptverfasser: Bakx, Tom J L C, Tamura, Yoichi, Hashimoto, Takuya, Inoue, Akio K, Lee, Minju M, Mawatari, Ken, Ota, Kazuaki, Umehata, Hideki, Zackrisson, Erik, Hatsukade, Bunyo, Kohno, Kotaro, Matsuda, Yuichi, Matsuo, Hiroshi, Okamoto, Takashi, Shibuya, Takatoshi, Shimizu, Ikkoh, Taniguchi, Yoshiaki, Yoshida, Naoki
Format: Journal Article
Sprache:Englisch
Veröffentlicht: London Oxford University Press 01.04.2020
Schlagworte:
Confidence limits
Continuum radiation
Cosmic dust
Dust
Galaxies
galaxies: formation
galaxies: high-redshift
galaxies: ISM
Interstellar matter
Interstellar radiation
Ionization
Luminosity
Photodissociation
Physical properties
Radio telescopes
galaxies: formation
galaxies: ISM
galaxies: high-redshift
ISSN:0035-8711, 1365-2966, 1365-2966
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Zusammenfassung:ABSTRACT We report on the detection of the [C ii] 157.7 μm emission from the Lyman break galaxy (LBG) MACS0416_Y1 at z = 8.3113, by using the Atacama Large Millimeter/submillimeter Array (ALMA). The luminosity ratio of [O iii] 88 μm (from previous campaigns) to [C ii] is 9.3 ± 2.6, indicative of hard interstellar radiation fields and/or a low covering fraction of photodissociation regions. The emission of [C ii] is cospatial to the 850 μm dust emission (90 μm rest frame, from previous campaigns), however the peak [C ii] emission does not agree with the peak [O iii] emission, suggesting that the lines originate from different conditions in the interstellar medium. We fail to detect continuum emission at 1.5 mm (160 μm rest frame) down to 18 μJy (3σ). This non-detection places a strong limits on the dust spectrum, considering the 137 ± 26 μJy continuum emission at 850 μm. This suggests an unusually warm dust component (T > 80 K, 90 per cent confidence limit), and/or a steep dust-emissivity index (βdust > 2), compared to galaxy-wide dust emission found at lower redshifts (typically T ∼ 30–50 K, βdust ∼ 1–2). If such temperatures are common, this would reduce the required dust mass and relax the dust production problem at the highest redshifts. We therefore warn against the use of only single-wavelength information to derive physical properties, recommend a more thorough examination of dust temperatures in the early Universe, and stress the need for instrumentation that probes the peak of warm dust in the Epoch of Reionization.
Bibliographie:ObjectType-Article-1
SourceType-Scholarly Journals-1
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content type line 14
ISSN:0035-8711
1365-2966
1365-2966
DOI:10.1093/mnras/staa509