期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 493, 期 3, 页码 4294-4307出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/staa509
关键词
galaxies: formation; galaxies: high-redshift; galaxies: ISM
资金
- NAOJ ALMA Scientific Research [2018-09B]
- JSPS KAKENHI [17H06130]
- Swedish National Space Board
- MEXT KAKENHI grant [18H04333, 19H01931]
- Leading Initiative for Excellent Young Researchers, MEXT, Japan
- Grants-in-Aid for Scientific Research [17H06130, 19H01931, 18H04333] Funding Source: KAKEN
We report on the detection of the [C II] 157.7 mu m 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 mu m (from previous campaigns) to [CII] 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 mu m dust emission (90 mu m 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 mu m rest frame) down to 18 mu Jy (3 sigma). This non-detection places a strong limits on the dust spectrum, considering the 137 +/- 26 mu Jy continuum emission at 850 mu m. This suggests an unusually warm dust component (T > 80 K, 90 per cent confidence limit), and/or a steep dust-emissivity index (beta(dust) > 2), compared to galaxy-wide dust emission found at lower redshifts (typically T similar to 30-50 K, beta(dust) similar to 1-2). If such temperatures are common, thiswould 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.
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