2014ApJ...783...71W

We present Karl G. Jansky Very Large Array (VLA) observations of 44 GHz continuum and CO J = 2-1 line emission in BRI 1202-0725 at z = 4.7 (a starburst galaxy and quasar pair) and BRI 1335-0417 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 BRI 1202-0725 are L'_CO = (8.7 ± 0.8) x 10¹⁰ K.km/s.pc2 and L'_CO = (6.0± 0.5) x 10¹⁰ K.km/s.pc2 for the submillimeter galaxy (SMG) and quasar, respectively, 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 ∼9x10¹⁰ M_☉. In BRI 1335-0417 we measure L'_CO = (7.3 ± 0.6) x 10¹⁰ K km/s pc². We detect continuum emission in the SMG BRI 1202-0725 North (S_44 GHz_= 51±6 µJy), while the quasar is detected with S_44 GHz_= 24±6 µJy and in BRI 1335-0417 we measure S_44 GHz_= 40±7 µJy. Combining our continuum observations with previous data at (rest-frame) far-infrared and centimeter 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%.