2017MNRAS.466..138K -
Mon. Not. R. Astron. Soc., 466, 138-146 (2017/March-3)
A merger in the dusty, z = 7.5 galaxy A1689-zD1?
KNUDSEN K.K., WATSON D., FRAYER D., CHRISTENSEN L., GALLAZZI A., MICHALOWSKI M.J., RICHARD J. and ZAVALA J.
Abstract (from CDS):
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 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 (Tdust ∼ 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] LFIR luminosity ratio suggest a [C II] deficit similar to several bright quasars and massive starbursts.
Abstract Copyright:
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
galaxies: evolution - galaxies: formation - galaxies: high-redshift - galaxies: ISM - submillimetre: galaxies - submillimetre: galaxies
Simbad objects:
4
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