Related papers: Galaxy Ages with Redshift z=2-4: Stellar Populatio…
Recent studies have reported a non evolution of galaxy ages at redshifts higher than $z\sim$ 2.5, as well as galaxies older than the Universe. In this work, a sample of galaxies from JWST and HST was analysed via photometry to further…
Recent James Webb Space Telescope (JWST) data analyses have shown that massive red galaxies existed at redshifts $z>6$, a discovery that is difficult to understand in the context of standard cosmology ($\Lambda $CDM). Here we analyze these…
In the early Universe finding massive galaxies that have stopped forming stars present an observational challenge as their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep…
In this invited talk I show how the reddest and rarest galaxies at high redshift ($z \simeq 1.5$) can be used to set the stellar evolution clock. I argue that one can confidently compute the collapse redshift of these objects. This yields…
We aim at improving constraints on the epoch of galaxy formation by measuring the ages of 3597 galaxies with spectroscopic redshifts 2<z<6.5 in the VIMOS Ultra Deep Survey (VUDS). We derive ages and other physical parameters from the…
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…
Our understanding of the redshift $z>3$ galaxy population relies largely on samples selected using the popular "dropout" technique, typically consisting of UV-bright galaxies with blue colors and prominent Lyman breaks. As it is currently…
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…
We explore the relations between size, stellar mass and average stellar population age (indicated by D$_n4000$ indices) for a sample of $\sim11000$ intermediate-redshift galaxies from the SHELS spectroscopic survey (Geller et al. 2014)…
We present low-resolution near-infrared stacked spectra from the 3D-HST survey up to $z=2.0$ and fit them with commonly used stellar population synthesis models: BC03 (Bruzual & Charlot, 2003), FSPS10 (Flexible Stellar Population Synthesis,…
We analyse publicly available, individual spectra of four, massive ($M>10^{11}M_{\odot}$) early-type galaxies with redshifts in the range 1.4 < z < 2 to determine their stellar content, extending our previous work up to z~2. The wide…
Major progress has been achieved in recent years in mapping the properties of passively-evolving, early-type galaxies (ETG) from the local universe all the way to redshift ~2. Here, age and metallicity estimates for local cluster and field…
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…
With a complete, mass-selected sample of quiescent galaxies from the NEWFIRM Medium-Band Survey (NMBS), we study the stellar populations of the oldest and most massive galaxies (>10^11 Msun) to high redshift. The sample includes 570…
From James Webb Space Telescope (JWST) surveys, 31 galaxies with average redshift 7.3 are selected containing large Balmer break, Lyman-$\alpha$ break (V-shaped SED versus $\lambda$). Apart from Hubble Space Telescope (HST) and JWST-NIRCam…
We have discovered a population of extremely red galaxies at $z\simeq 1.5$ which have apparent stellar ages of $\gs 3$ Gyr, based on detailed spectroscopy in the rest-frame ultraviolet. In order for galaxies to have existed at the high…
Based on VLT/FORS spectroscopy and HST/ACS imaging, we have constructed a sample of ~200 field spiral galaxies that cover redshifts up to z~1. Such a large data set allows to study the evolution of fundamental galaxy parameters like…
We present spectroscopic evidence from the Gemini Deep Deep Survey (GDDS) for a significant population of color-selected red galaxies at 1.3 < z < 2.2 whose integrated light is dominated by evolved stars. Unlike radio-selected objects, the…
The most passive galaxies at high redshift are unlikely to be identified by either narrow-band emission-line searches, or by Lyman limit searches (both techniques which have been highlighted at this meeting) simply because such selection…
I review the current status of an on-going investigation into the stellar and dynamical ages of the oldest known galaxies at redshifts greater than 1. The spectroscopic data, when compared with the predictions of a range of recent…