2000ApJ...528..626P

We report the detection of submillimeter emission from dust at 850 µm and of the ¹²CO J=4-3 line in the two distant powerful radio galaxies 4C 60.07 (z=3.79) and 6C 1909+722 (z=3.53). In 4C 60.07, the dust emission is also detected at 1.25 mm. The estimated molecular gas masses are large, of the order of ~(0.5-1)x10¹¹ M_☉. The large far-infrared (FIR) luminosities (L_FIR∼10¹³ L_☉) suggest that we are witnessing two major starburst phenomena, while the observed large velocity widths (ΔV_FWHM≳500 km.s^–1) are characteristic of mergers. In the case of 4C 60.07, the CO emission extends over ∼30 kpc and spans a velocity range of ≳1000 km.s^–1. It consists of two distinct features with FWHM of ≳550 km.s^–1 and ∼150 km.s^–1, and line centers separated by ≳700 km.s^–1. The least massive of these components is probably very gas rich, with potentially ≳60% of its dynamical mass in the form of molecular gas. The extraordinary morphology of the CO emission in this object suggests that it is not just a scaled-up version of a local ultraluminous infrared galaxy, and it may be a formative stage of the elliptical host of the residing radio-loud active galactic nucleus (AGN). Finally, we briefly explore the effects of the wide range of gas-excitation conditions expected for starburst environments on the luminosity of high-J CO lines and conclude that in unlensed objects, CO (J+1⟶J), J+1>3 lines can be significantly weak with respect to CO J=1-0, and this can hinder their detection even in the presence of substantial molecular gas masses.