科研之友
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摘要
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 the IRAM/Plateau de Bure Interferometer for molecular (H-2) gas in a massive (M-star similar to 6 x 10(11) M-circle dot) elliptical galaxy at z= 1.4277, the first observation of this kind ever attempted. We place a 3 sigma upper limit of 0.32 Jy kms(-1) on the flux of the CO-(J = 2 -> 1) line or L-CO' < 8.8 x 10(9) Kkms(-1) pc(2), 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 H-2 mass of < 3.9 x 10(10) (alpha(CO)/4.4) M-circle dot or a gas fraction of less than or similar to 6% assuming a Salpeter initial mass function and an ISM dominated by H-2, as observed in many local, high-mass ellipticals. This low value approaches that of local ETGs, suggesting that the low star formation activity in massive, high-z passive galaxies reflects a true dearth of gas and a lesser role for inhibitive mechanisms like morphological quenching.
- 出版日期2015-6-10
- 单位中国地震局
