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|Title:||A merger in the dusty, z = 7.5 galaxy A1689-zD1?||Authors:||Knudsen, Kirsten K.
GALLAZZI, Anna Rita
Michałowski, Michał J.
|Issue Date:||2017||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||466||Issue:||1||First Page:||138||Abstract:||The gravitationally lensed galaxy A1689-zD1 is one of the most distant spectroscopically confirmed sources (z = 7.5). It is the earliest known galaxy where the interstellar medium (ISM) has been detected; dust emission was detected with the Atacama Large Millimetre Array (ALMA). A1689-zD1 is also unusual among high-redshift dust emitters as it is a sub-L<SUP>★</SUP> galaxy and is therefore a good prospect for the detection of gaseous ISM in a more typical galaxy at this redshift. We observed A1689-zD1 with ALMA in bands 6 and 7 and with the Green Bank Telescope (GBT) in band Q. To study the structure of A1689-zD1, we map the mm-thermal dust emission and find two spatial components with sizes about 0.4 - 1.7 kpc (lensing-corrected). The rough spatial morphology is similar to what is observed in the near-infrared with HST and points to a perturbed dynamical state, perhaps indicative of a major merger or a disc in early formation. The ALMA photometry is used to constrain the far-infrared spectral energy distribution, yielding a dust temperature (T<SUB>dust</SUB> ∼ 35-45 K for β = 1.5 - 2). We do not detect the CO(3-2) line in the GBT data with a 95 per cent upper limit of 0.3 mJy observed. We find a slight excess emission in ALMA band 6 at 220.9 GHz. If this excess is real, it is likely due to emission from the [C II] 158.8 μm line at z_[C II] = 7.603. The stringent upper limits on the [C II] L<SUB>FIR</SUB> luminosity ratio suggest a [C II] deficit similar to several bright quasars and massive starbursts.||URI:||http://hdl.handle.net/20.500.12386/27019||URL:||https://academic.oup.com/mnras/article/466/1/138/2608767||ISSN:||0035-8711||DOI:||10.1093/mnras/stw3066||Bibcode ADS:||2017MNRAS.466..138K||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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