科研之友
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摘要
We use an adaptation of the BzK(s) technique to select similar to 40 000 z similar to 2 galaxies (to K-AB = 24), including similar to 5000 passively evolving (PE) objects (to K-AB = 23), from 2.5 deg(2) of deep Canada-France-Hawaii Telescope (CFHT) imaging. The passive galaxy luminosity LF) exhibits a clear peak at R = 22 and a declining faint-end slope (alpha = -0.12(-0.14)(+0.16)), while that of star-forming galaxies is characterized by a steep faint-end slope [alpha = -1.43 +/- 0.02(systematic)(-0.04)(+0.05)(random)]. The details of the LFs are somewhat sensitive (at the <25 per cent level) to cosmic variance even in these large (similar to 0.5 deg(2)) fields, with the D2 field (located in the Cosmological Evolution Survey, COSMOS field) most discrepant from the mean. The shape of the z similar to 2 stellar mass function of passive galaxies is remarkably similar to that at z similar to 0.9, save for a factor of similar to 4 lower number density. This similarity suggests that the same mechanism may be responsible for the formation of passive galaxies seen at both these epochs. This same formation mechanism may also operate down to z similar to 0 if the local PE galaxy mass function, known to be two-component, contains two distinct galaxy populations. This scenario is qualitatively in agreement with recent phenomenological mass-quenching models and extends them to span more than three quarters of the history of the Universe.
- 出版日期2013-10
