Detection of CO J = 1-0 in the z = 3.79 radio galaxy 4C 60.07

Abstract

We report on the detection of the lowest CO J=1-0 transition in the powerful high-redshift radio galaxy 4C 60.07 at z = 3.79. The CO emission is distributed in two spatially and kinematically distinct components as was previously known from the observations of the higher excitation CO J = 4-3 line. The total molecular gas mass in 4C 60.07 inferred from the CO J = 1-0 emission is M(H2) ≃ 1.3 × 1011 M⊙, sufficient to fuel the inferred star-formation rate of ∼1600 M ⊙ yr-1 for 108 yrs. From our high-resolution CO J = 1-0 VLA maps we find the dynamical mass of 4C 60.07 to be comparable to that of a giant elliptical at the present time. A significant fraction of the mass is in the form of molecular gas suggesting that 4C 60.07 is in an early state of its evolution. The merging nature of 4C 60.07 along with its large dynamical mass imply that this system is a giant elliptical caught in its formative stages.