The average structural evolution of massive galaxies can be reliably estimated using cumulative galaxy number densities
Abstract
Galaxy evolution can be studied observationally by linking progenitor and descendant galaxies through an evolving cumulative number density (CND) selection. This procedure can reproduce the expected evolution of the median stellar mass from abundance matching. However, models predict an increasing scatter in main progenitor masses at higher redshifts, which makes galaxy selection at the median mass unrepresentative. Consequently, there is no guarantee that the evolution of other galaxy properties deduced from this selection is reliable. Despite this concern, we show that this procedure approximately reproduces the evolution of the average stellar density profile of main progenitors of M ≈ 1011.5M⊙ galaxies, when applied to the EAGLE hydrodynamical simulation. At z ≳ 3.5, the aperture masses disagree by about a factor 2, but this discrepancy disappears when we include the expected scatter in cumulative number densities. The evolution of the average density profile in EAGLE broadly agrees with observations from UltraVISTA and CANDELS, suggesting an inside-out growth history for these massive galaxies over 0 ≲ z ≲ 5. However, for z ≲ 2, the inside-out growth trend is stronger in EAGLE. We conclude that CND matching gives reasonably accurate results when applied to the evolution of the mean density profile of massive galaxies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 2017
- DOI:
- 10.1093/mnrasl/slx055
- arXiv:
- arXiv:1703.02568
- Bibcode:
- 2017MNRAS.469L..58C
- Keywords:
-
- galaxies: evolution;
- galaxies: high-redshift;
- galaxies: structure;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 5 pages, 4 figures, Accepted by MNRAS Letters