Abstract
The link between massive red galaxies in the local Universe and star-forming galaxies at high redshift is investigated with a semi-analytic model that has proven successful in many ways, e.g. explaining the galaxy colour-magnitude bimodality and the stellar mass-age relation for red-sequence galaxies. The model is used to explore the processes that drive star formation in different types of galaxies as a function of stellar mass and redshift. We find that most z=2-4 star-forming galaxies with M_*>10^10 M_Sun evolve into red-sequence galaxies. Also, most of the massive galaxies on the red-sequence today have passed through a phase of intense star formation at z>2. Specifically, ~ 90% of today's red galaxies with M_*>10^11 M_Sun were fed during this phase by cold streams including minor mergers. Gas-rich major mergers are rare and the effects of merger-driven starbursts are ephemeral. On the other hand, major mergers are important in powering the most extreme starbursts. Gas-rich mergers also explain the tail of intermediate-mass red galaxies that form relatively late, after the epoch of peak star formation. In two thirds of the currently red galaxies that had an intense star formation event at $z<1$, this event was triggered by a merger.
Highlights
Sub-mm observations have uncovered a new population of high-z star-forming galaxies (SFGs), which are detected through the far-infrared emission of dust heated by UVbright newborn stars (Smail et al 1997; Eales et al 1999)
If we look at this specific population, the percentages of galaxies with merger-driven star formation rate (SFR) peaks rise to 56%, 80% and 67%
We find that: i) most galaxies that have experienced SFRs > 40 M⊙ yr−1 evolve into red-sequence galaxies, ii) 80% of the red-sequence galaxies with M∗ > 1011M⊙ passed through a phase of high SFR (SFRpeak > 40 M⊙ yr−1) at z > 1, and iii) in ∼> 90% of these cases, this phase was stream-fed
Summary
Sub-mm observations have uncovered a new population of high-z star-forming galaxies (SFGs), which are detected through the far-infrared emission of dust heated by UVbright newborn stars (Smail et al 1997; Eales et al 1999) These lie along a sequence in the star formation rate (SFR)stellar mass plane that is elevated with respect to the z = 0 relation (Noeske et al 2007b; Elbaz et al 2011). The main progenitor of a z = 0 elliptical may be a clumpy disc at z = 4, a major gas-rich merger at z = 3, and a massive red object at z = 2 We resolve this ambiguity by introducing the redshift zpeak at which the star formation rate (SFR) of a galaxy’s main progenitor has an absolute maximum.
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