Abstract / Description of output
We use a large sample of ∼350 000 galaxies constructed by combining the
UKIDSS UDS, VIDEO/CFHT-LS, UltraVISTA/COSMOS and GAMA survey regions to
probe the major (1:4 stellar mass ratio) merging histories of massive
galaxies (>1010 M⊙) at 0.005 < z < 3.5.
We use a method adapted from that presented in López-Sanjuan et al.,
using the full photometric redshift probability distributions, to
measure pair fractions of flux-limited, stellar mass selected
galaxy samples using close-pair statistics. The pair fraction is found
to weakly evolve as ∝ (1 + z)0.8 with no dependence on stellar mass. We subsequently derive major merger rates for galaxies at >1010 M⊙ and at a constant number density of n > 10−4 Mpc−3,
and find rates a factor of 2–3 smaller than previous works, although
this depends strongly on the assumed merger time-scale and likelihood of
a close-pair merging. Galaxies undergo approximately 0.5 major mergers
at z < 3.5, accruing an additional (1–4) × 1010 M⊙
in the process. On average, this represents an increase in stellar mass
of 20–30 per cent (40–70 per cent) for constant stellar mass (constant
number density) samples. Major merger accretion rate densities of
∼2 × 10−4 M⊙ yr−1 Mpc−3 are found for number density selected samples, indicating that direct progenitors of local massive (>1011 M⊙)
galaxies have experienced a steady supply of stellar mass via major
mergers throughout their evolution. While pair fractions are found to
agree with those predicted by the Henriques et al. semi-analytic model,
the Illustris hydrodynamical simulation fails to quantitatively
reproduce derived merger rates. Furthermore, we find that major mergers
become a comparable source of stellar mass growth compared to star
formation at z < 1, but is 10–100 times smaller than the star formation rate density at higher redshifts.
Original language | English |
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Pages (from-to) | 3507-3531 |
Number of pages | 25 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 470 |
Issue number | 3 |
Early online date | 22 May 2017 |
DOIs | |
Publication status | Published - 1 Sept 2017 |
Keywords / Materials (for Non-textual outputs)
- astro-ph.GA
- astro-ph.CO
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Dive into the research topics of 'A consistent measure of the merger histories of massive galaxies using close-pair statistics I: Major mergers at z <3.5'. Together they form a unique fingerprint.Profiles
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Kenneth Duncan
- School of Physics and Astronomy - Reader in Galaxy Evolution
Person: Academic: Research Active