Related papers: A massive, quiescent galaxy at redshift of z=3.717
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…
Within the established framework of structure formation, galaxies start as systems of low stellar mass and gradually grow into far more massive galaxies. The existence of massive galaxies in the first billion years of the Universe,…
We present the discovery of a massive, quiescent galaxy at z=2.99. We have obtained a HST/WFC3 spectrum of this object and measured its redshift from the detection of a deep 4000A break consistent with an old population and a high…
The extremely rapid assembly of the earliest galaxies during the first billion years of cosmic history is a major challenge for our understanding of galaxy formation physics. The advent of JWST has exacerbated this issue by confirming the…
We report two secure ($z=3.775, 4.012$) and one tentative ($z\approx3.767$) spectroscopic confirmations of massive and quiescent galaxies through $K$-band observations with Keck/MOSFIRE and VLT/X-Shooter. The stellar continuum emission, the…
We report a robust sample of 10 massive quiescent galaxies at redshift, $z > 3$, selected using the first data from the JWST CEERS programme. Three of these galaxies are at $4 < z < 5$, constituting the best evidence to date for quiescent…
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…
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…
Here we present a sample of 12 massive quiescent galaxy candidates at z~3-4 observed with the James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec). These galaxies were pre-selected from the Hubble Space Telescope imaging…
We investigate the stellar populations for a sample of 161 massive, mainly quiescent galaxies at $\langle z_{\rm obs} \rangle=0.8$ with deep Keck/DEIMOS rest-frame optical spectroscopy (HALO7D survey). With the fully Bayesian framework…
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…
We present spectra of the most massive quiescent galaxy yet discovered at $z>3$, spectroscopically confirmed via the detection of Balmer absorption features in the $H-$ and $K-$bands of Keck/MOSFIRE. The spectra confirm a galaxy with no…
A puzzling population of extremely massive quiescent galaxies at redshifts beyond z=3 has recently been revealed by JWST and ALMA, some of them with stellar ages that show their quenching times to be as high as z=6, while their stellar…
The measured ages of massive, quiescent galaxies at $z\sim 3-4$ imply that massive galaxies quench as early as $z\sim 6$. While the number of spectroscopic confirmations of quiescent galaxies at $z < 3$ has increased over the years, there…
The complex problem of when and how galaxies formed has not until recently been susceptible of direct attack. It has been known for some time that the excessive number of blue galaxies counted at faint magnitudes implies that a considerable…
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…
Massive quiescent galaxies at high redshift can shed light on the processes of galaxy mass assembly and quenching of the star formation at early epochs. We present observer-frame color-color diagrams designed to identify candidate quiescent…
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…
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…
Local and low-redshift ($z$<$3$) galaxies are known to broadly follow a bimodal distribution: actively star forming galaxies with relatively stable star-formation rates, and passive systems. These two populations are connected by galaxies…