Related papers: When did the Large Elliptical Galaxies Form?
Massive galaxies, such as nearby ellipticals, have relatively low number densities, yet they host the majority of the stellar mass in the universe. Understanding their origin is a central problem of galaxy formation. Age dating of stellar…
At redshift z = 2, when the Universe was just three billion years old, half of the most massive galaxies were extremely compact and had already exhausted their fuel for star formation(1-4). It is believed that they were formed in intense…
I present a biased review of when the epoch of formation of galaxies (both disks and ellipticals) maybe took place. I base my arguments in simple (mostly) analytic models that have been recently developed to reproduce most of the observed…
A major goal of contemporary astrophysics is understanding the origin of the most massive galaxies in the universe, particularly nearby ellipticals and spirals. Theoretical models of galaxy formation have existed for many decades, although…
Stellar archeology shows that massive elliptical galaxies today formed rapidly about ten billion years ago with star formation rates above several hundreds solar masses per year (M_sun/yr). Their progenitors are likely the…
The history of galaxy formation via star formation and stellar mass assembly rates is now known with some certainty, yet the connection between high redshift and low redshift galaxy populations is not yet clear. By identifying and studying…
I review the current status of understanding when, how long, and how giant elliptical galaxies formed, focusing on the globular clusters. Several observational evidences show that massive elliptical galaxies formed at $z>2$ ($>10$ Gyr ago).…
In the early Universe finding massive galaxies that have stopped forming stars present an observational challenge as their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep…
Understanding the formation history of massive galaxies is one of most popular and longstanding problems in astronomy, with observations and theory addressing how and when these systems assembled. Since the most massive galaxies in today's…
Star formation history shows a gradual decline since the last 8-9 Gyr (z=1). The bulk of present-day stellar mass and metal content was formed at redshifts lower than 2-3, which is consistent with a hierarchical scenario of galaxy…
The traditional view of elliptical galaxies has been that they formed in a single, rapid burst of star formation at high redshift, and have evolved quiescently since that time. In opposition to this traditional view is evidence that at…
The structural properties of elliptical galaxies are consistent with their formation in a merging hierarchy. In this picture, the role of gaseous processes and dissipation decreased with increasing mass creating preferentially rotationally…
When galaxy formation started in the history of the Universe remains unclear. Studies of the cosmic microwave background indicate that the Universe, after initial cooling (following the Big Bang), was reheated and reionized by hot stars in…
The current evidence about the age of stellar populations in elliptical galaxies is reviewed. The case for the bulk of stars in galactic spheroids (ellipticals and bulges) having formed at high redshift (z>~3) is now compelling, both for…
Observing massive galaxies at various redshifts is one of the most straightforward and direct approaches towards understanding galaxy formation. There is now largely a consensus that the massive galaxy (M_* > 10^11 M_0) population is fully…
I discuss current observational constraints on the star-formation and stellar-assembly histories of galaxies at high redshifts. The data on massive galaxies at z<1 implies that their stellar populations formed at z>2, and that their…
Star formation in elliptical galaxies (Es) was and is mostly dominated by mergers and accretions with many suggestive examples seen among local galaxies. Present day star formation in Es is easily measurable in two thirds of Es and appears…
The existence of massive ($10^{11}$ solar masses) elliptical galaxies by redshift z~4 (when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z>6…
In hierarchical models of galaxy formation, ellipticals form from the merging of disk galaxies drawn together by gravity as their surrounding dark halos coalesce. Using semi-analytic techniques, we are able to follow the merging, star…
The formation of galaxies by gradual hierarchical co-assembly of baryons and cold dark matter halos is a fundamental paradigm underpinning modern astrophysics and predicts a strong decline in the number of massive galaxies at early cosmic…