1,327 research outputs found
What Regulates Galaxy Evolution? Open Questions in Our Understanding of Galaxy Formation and Evolution
In April 2013, a workshop entitled "What Regulates Galaxy Evolution" was held
at the Lorentz Center. The aim of the workshop was to bring together the
observational and theoretical community working on galaxy evolution, and to
discuss in depth of the current problems in the subject, as well as to review
the most recent observational constraints. A total of 42 astrophysicists
attended the workshop. A significant fraction of the time was devoted to
identifying the most interesting "open questions" in the field, and to discuss
how progress can be made. This review discusses the four questions (one for
each day of the workshop) that, in our opinion, were the focus of the most
intense debate. We present each question in its context, and close with a
discussion of what future directions should be pursued in order to make
progress on these problems.Comment: 36 pages, 6 Figures, submitted to New Astronomy Review
The Mass Growth and Stellar Ages of Galaxies: Observations versus Simulations
Using observed stellar mass functions out to , we measure the main
progenitor stellar mass growth of descendant galaxies with masses of
at using an evolving
cumulative number density selection. From these mass growth histories, we are
able to measure the time at which half the total stellar mass of the descendant
galaxy was assembled, , which, in order of decreasing mass corresponds
to redshifts of and . We compare this to the
median light-weighted stellar age ( and
) of a sample of low redshift SDSS galaxies (from the literature) and
find the timescales are consistent with more massive galaxies forming a higher
fraction of their stars ex-situ compared to lower mass descendants. We find
that both and strongly correlate with mass which is in contrast
to what is found in the EAGLE hydrodynamical simulation which shows a flat
relationship between and . However, the semi-analytic model of
\citet{henriques2015} is consistent with the observations in both and
with , showing the most recent semi-analytic models are better
able to decouple the evolution of the baryons from the dark matter in
lower-mass galaxies.Comment: 6 pages, 3 figures, accepted for publication in ApJ
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