A direct constraint on the gas content of a massive, passively evolving elliptical galaxy at z = 1.43

Gas and dust in star-forming galaxies at the peak epoch of galaxy assembly are presently the topic of intense study, but little is known about the interstellar medium (ISM) of distant, passively evolving galaxies. We report on a deep 3 mm-band search with IRAM/PdBI for molecular (H2) gas in a massive (M⋆∼6×1011M⊙) elliptical galaxy at z=1.4277, the first observation of this kind ever attempted. We place a 3σ upper limit of 0.32 Jy km/s on the flux of the CO(J=2→1) line or L′CO<8.8×109 K km/s pc2, assuming a disk-like CO-morphology and a circular velocity scaling with the stellar velocity dispersion as in local early-type galaxies (ETGs). This translates to an H2 mass of