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* 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. We map the mm thermal dust
emission, confirming the large dust emission found before, and finding 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 moderate dust temperature
($T_dust 35$ K for $= 1.65$). We do not detect the CO(3-2)
line in the GBT data with a 95% upper limit of 0.3mJy 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 CII 158.8 $\mu$m line at $z_CII =
7.603$. The stringent upper limits on the CII and CO(3-2) line luminosities
suggest a high ISM gas density in A1689-zD1.
Users
Please
log in to take part in the discussion (add own reviews or comments).