Related papers: Old Galaxies in the Young Universe
It has been widely remarked that compact, massive, elliptical-like galaxies are abundant at high redshifts but exceedingly rare in the Universe today, implying significant evolution such that their sizes at z ~ 2+/-0.6 have increased by…
The genesis of spheroids is central to our understanding of galaxy formation -- they are relatively simple systems, containing about half the stellar mass of the Universe. A major subset of spheroids, massive elliptical galaxies, are…
We study ~330 massive (M* > 10^9.5 MSun), newborn spheroidal galaxies (SGs) around the epoch of peak star formation (1<z<3), to explore the high-redshift origin of SGs and gain insight into when and how the old stellar populations that…
We use high-resolution simulations to show that the current standard paradigm for the growth of structure in the Universe predicts the formation of a galaxy like our own to differ substantially from the classic ELS and Searle/Zinn pictures.…
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…
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…
There are at least three reasons for being interested in galaxies at high redshifts that formed most of their stars quite quickly early in the history of the Universe: (1) the ages of their stellar populations can potentially place…
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…
Observational evidence has been mounting over the past decade that at least some luminous (~2 L*) galaxies have formed nearly all of their stars within a short period of time only 1-2x10^9 years after the Big Bang. These are examples of the…
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…
Galaxies exhibit a sequence of various morphological types, i.e., the Hubble sequence, and they are basically composed of spheroidal components (elliptical galaxies and bulges in spiral galaxies) and disks. It is known that spheroidal…
Present-day massive galaxies are composed mostly of early-type objects. It is unknown whether this was also the case at higher redshifts. In a hierarchical assembling scenario the morphological content of the massive population is expected…
We report preliminary results of a project to homogeneously measure star formation histories for the majority of Local Group dwarf galaxies, based on archival WFPC2 observations. For the dwarf spheroidal and elliptical galaxies, we find…
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…
The most massive galaxies in the present-day Universe are found to lie in the centres of rich clusters. They have old, coeval stellar populations suggesting that the bulk of their stars must have formed at early epochs in spectacular…
To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs. Galaxies in the young Universe have hitherto mainly been identified using their expected…
Superdense massive galaxies (r_e~1 kpc; M~10^{11} Msun) were common in the early universe (z>1.5). Within some hierarchical merging scenarios, a non-negligible fraction (1-10%) of these galaxies is expected to survive since that epoch…
Many galaxies appear to have taken on their familiar appearance relatively recently. In the distant Universe, galaxy morphology started to deviate significantly (and systematically) from that of nearby galaxies at redshifts, z, as low as z…
Our current knowledge of cosmic star-formation history during the first two billion years (corresponding to redshift z >3) is mainly based on galaxies identified in rest-frame ultraviolet light. However, this population of galaxies is known…
Early-type galaxies are considered to be the end-products of massive galaxy formation. Optical spectroscopic studies reveal that massive early-type galaxies formed the bulk of their stars over short timescales (1<Gyr) and at high redshift…