Karl G. Jansky Very Large Array observations of cold dust and molecular gas in starbursting quasar host galaxies at z ~ 4.5
The Astrophysical Journal
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Wagg, J., Carilli, C., Aravena, M., Cox, P., Lentati, L., Maiolino, R., McMahon, R., et al. (2014). Karl G. Jansky Very Large Array observations of cold dust and molecular gas in starbursting quasar host galaxies at z ~ 4.5. The Astrophysical Journal, 783 71. https://doi.org/10.1088/0004-637X/783/2/71
We present Karl G. Jansky Very Large Array (VLA) observations of 44 GHz continuum and CO J=2–1 line emission in BR1202-0725 at z = 4.7 (a starburst galaxy and quasar pair) and RI1335-0417 at z = 4.4 (also hosting a quasar). With the full 8 GHz bandwidth capabilities of the upgraded VLA, we study the (rest-frame) 250 GHz thermal dust continuum emission for the first time along with the cold molecular gas traced by the low-J CO line emission. The measured CO J=2–1 line luminosities of BR1202-0725 are L′CO = (8.7 ± 0.8) × 1010 K km s−1 pc2 and L′CO = (6.0 ± 0.5) × 1010 K km s−1 pc2 for the submm galaxy (SMG) and quasar, which are equal to previous measurements of the COJ=5–4 line luminosities implying thermalized line emission and we estimate a combined cold molecular gas mass of 9×1010 M⊙. In BRI1335-0417 we measure L′CO = (7.3 ± 0.6) × 1010 K km s−1 pc2. We detect continuum emission in the SMG BR1202-0725 North (S44GHz = 51 ± 6 μJy), while the quasar is detected with S44GHz = 24±6 μJy and in BRI1335-0417 we measure S44GHz = 40±7 μJy. Combining our continuum observations with previous data at (rest-frame) far-infrared and cm-wavelengths, we fit three component models in order to estimate the star-formation rates. This spectral energy distribution fitting suggests that the dominant contribution to the observed 44 GHz continuum is thermal dust emission, while either thermal free-free or synchrotron emission contributes less than 30%.
This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). We thank all those involved in the VLA project for making these observations possible (project code 13A-012).
External DOI: https://doi.org/10.1088/0004-637X/783/2/71
This record's URL: https://www.repository.cam.ac.uk/handle/1810/245745