相关论文: ZF-UDS-7329: A relic galaxy in the early Universe

We present a detailed analysis of JWST/NIRSpec and NIRCam observations of ZF-UDS-7329, a massive, quiescent galaxy at redshift $z=3.2$, which has been put forward to challenge cosmology and galaxy formation physics. We study on the impact…

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…

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…

We report ultra-deep, medium-resolution spectroscopic observations for 4 quiescent galaxies with log$_{10}(M_*/\mathrm{M_\odot})>11$ at $3 < z < 5$. These data were obtained with JWST NIRSpec as part of the Early eXtragalactic Continuum and…

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…

Globular clusters (GCs) are some of the oldest bound structures in the Universe, holding clues to the earliest epochs of star formation and galaxy assembly. However, accurate age measurements of ancient clusters are challenging due to the…

Unlike spiral galaxies such as the Milky Way, the majority of the stars in massive elliptical galaxies were formed in a short period early in the history of the Universe. The duration of this formation period can be measured using the ratio…

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…

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 derive the stellar population parameters of 11 quiescent ultra-diffuse galaxies (UDGs) from Keck/KCWI data. We supplement these with 14 literature UDGs, creating the largest spectroscopic sample of UDGs to date (25). We find a strong…

We present a detailed stellar population analysis of 27 massive elliptical galaxies within 4 very rich clusters at redshift z~0.2. We obtained accurate estimates of the mean luminosity-weighted ages and relative abundances of CN, Mg and Fe…

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…

We confirm two new local massive relic galaxies, i.e. untouched survivors of the early universe massive population: Mrk1216 and PGC032873. Both show early and peaked formation events within very short timescales (<1 Gyr) and thus old mean…

In this work, we compare star formation histories of massive (10.5 $< \log(\mathrm{M_*/M_{\odot}}) <$ 12) galaxies in the UniverseMachine model to those measured from the Large Early Galaxy Astrophysics Census (LEGA-C) at $0.6<z<1$.…

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,…

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…

As early as 10 Gyr ago, galaxies with more than 10^11 Msun in stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction…

Recent stellar chemical abundance measurements of a handful of $z\sim2$ quiescent galaxies have suggested these galaxies exhibit a remarkably strong $\alpha$-enhancement compared to their local and intermediate redshift counterparts. This…

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…

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…