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A merger in the dusty, z=7.5 galaxy A1689-zD1?

Kirsten Kraiberg Knudsen (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; D. Watson ; D. Frayer ; L. Christensen ; A. Gallazzi ; M. J. Michalowski ; J. Richard ; J. Zavala
Monthly Notices of the Royal Astronomical Society (0035-8711). Vol. 466 (2017), 1, p. 138-146.
[Artikel, refereegranskad vetenskaplig]

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 (T-dust similar to 35-45 K for beta = 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 Pi] 158.8 mu m line at z([C II]) = 7.603. The stringent upper limits on the [C coproduct] L-FIR luminosity ratio suggest a [C coproduct] deficit similar to several bright quasars and massive starbursts.

Nyckelord: galaxies: evolution, galaxies: formation, galaxies: high-redshift, galaxies: ISM, submillimetre: galaxies

Denna post skapades 2017-05-08. Senast ändrad 2017-11-08.
CPL Pubid: 249164


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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium (2010-2017)


Astronomi, astrofysik och kosmologi

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