Schinnerer, ECarilli, CLCapak, PMartinez-Sansigre, AScoville, NZSmolcic, VTaniguchi, YYun, MinBertoldi, FFe Fevre, Ode Ravel, L2024-04-262024-04-262008-01-01https://doi.org/10.1088/0004-637X/713/1/503https://hdl.handle.net/20.500.14394/2756<p>This is the pre-published version harvested from ArXiv. The published version is located at <a href="http://iopscience.iop.org/1538-4357/689/1/L5/">http://iopscience.iop.org/1538-4357/689/1/L5/</a></p>We report the detection of CO molecular line emission in the z = 4.5 millimeter-detected galaxy COSMOS J100054+023436 (hereafter J1000+0234) using the IRAM Plateau de Bure interferometer (PdBI) and NRAO's Very Large Array (VLA). The 12CO(4-3) line as observed with PdBI has a full line width of ~1000 km s−1, an integrated line flux of 0.66 Jy km s−1, and a CO luminosity of 3.2 × 1010 L. Comparison to the 3.3 σ detection of the CO(2-1) line emission with the VLA suggests that the molecular gas is likely thermalized to the J = 4–3 transition level. The corresponding molecular gas mass is 2.6 × 1010 M assuming an ULIRG-like conversion factor. From the spatial offset of the red- and blueshifted line peaks and the line width a dynamical mass of 1.1 × 1011 M is estimated assuming a merging scenario. The molecular gas distribution coincides with the rest-frame optical and radio position of the object while being offset by 0.5'' from the previously detected Lyα emission. J1000+0234 exhibits very typical properties for lower redshift (z ~ 2) submillimeter galaxies (SMGs) and thus is very likely one of the long sought after high-redshift (z > 4) objects of this population. The large CO(4-3) line width taken together with its highly disturbed rest-frame UV geometry suggest an ongoing major merger about a billion years after the big bang. Given its large star formation rate (SFR) of >1000 M yr−1 and molecular gas content this object could be the precursor of a "red and dead" elliptical observed at a redshift of z = 2.galaxies: formation; galaxies: high-redshift; galaxies: ISM; galaxies: starburst; submillimeterAstrophysics and Astronomyarticle