Science with the new extragalactic radio surveys
ALMA finds dew drops in the dusty spider's web
Bitten Gullberg
Matthew D. Lehnert (Institut d'Astrophysique de Paris), Carlos De Breuck (ESO, Garching) et al.
Centre for Extragalactic Astronomy, Durham University
The high-z radio galaxy (HzRG) MRC1138-262 at z=2.161 is one of the best studied HzRG with a well sampled spectral energy distribution that covers from radio to X-ray. Its radio morphology is typical of distant radio galaxies with a string of radio bright knots along the radio jet that extends to the west and a single lobe to the east of the radio core. I will present our 0.5’’ resolution ALMA detections of the observed 246 GHz continuum, [CI]2-1, CO(7-6), and H2O lines in MRC1138-262. We detect strong [CI]2-1 emission both at the position of the radio core, and in a second component ~4kpc away from it. The total CO(7-6)/[CI]2-1 line flux ratio of 0.2 suggests a low excitation molecular gas reservoir and/or enhanced atomic carbon in cosmic ray dominated regions. We detect spatially-resolved H2O emission - for the first time in a high-z unlensed galaxy - near the outer radio lobe to the east, and near the bend of the radio jet to the west of the HzRG. No underlying 246GHz continuum emission is seen at either position. Which suggest that the H2O emission is excited in the cooling region behind slow (10-40 km/s) shocks in dense molecular gas (10^3-5 cm^-3). This is likely evidence of the radio jet's impact on cooling and forming molecules in the post-shocked gas in the halo and inter-cluster gas.


13:30 - 15:00
EX - LT1 (100)