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arXiv · 1401.1213

Karl G. Jansky Very Large Array observations of cold dust and molecular gas in starbursting quasar host galaxies at z~4.5

J. Wagg·C. L. Carilli·M. Aravena·P. Cox·L. Lentati·R. Maiolino·R. G. McMahon·D. Riechers·F. Walter·P. Andreani·R. Hills·A. Wolfe
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Abstract

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 BRI1335-0417 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)x10^10 K km/s pc^2 and L'(CO) = (6.0+/-0.5)x10^10 K km/s pc^2 for the submm galaxy (SMG) and quasar, which are equal to previous measurements of the CO J=5-4 line luminosities implying thermalized line emission and we estimate a combined cold molecular gas mass of ~9x10^10 Msun. In BRI1335-0417 we measure L'(CO) = (7.3+/-0.6)x10^10 K km/s pc^2. We detect continuum emission in the SMG BR1202-0725 North (S(44GHz) = 51+/-6 microJy), while the quasar is detected with S(44GHz) = 24+/-6 microJy and in BRI1335-0417 we measure S(44GHz) = 40+/-7 microJy. 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%.

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J. Wagg, C. L. Carilli, M. Aravena, P. Cox, L. Lentati, R. Maiolino, R. G. McMahon, D. Riechers, F. Walter, P. Andreani, R. Hills, A. Wolfe. 2014-01-06. Karl G. Jansky Very Large Array observations of cold dust and molecular gas in starbursting quasar host galaxies at z~4.5. https://doi.org/10.1088/0004-637x%2F783%2F2%2F71

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