Related papers: Insights from HST into Ultra-Massive Galaxies and …
An unprecedented array of new observational capabilities are starting to yield key constraints on models of the epoch of first light in the Universe. In this Letter we discuss the implications of the UV radiation background at cosmic dawn…
JWST has revealed a large population of ultra-violet (UV)-bright galaxies at $z\gtrsim 10$ and possibly overly massive galaxies at $z\gtrsim 7$, challenging standard galaxy formation models in the $\Lambda$CDM cosmology. We use an empirical…
Early JWST observations have revealed a high-redshift universe more vibrant than predicted by canonical galaxy-formation models within $\Lambda$CDM, showing an excess of ultraviolet(UV)-bright, massive, and morphologically mature galaxies.…
Recent JWST observations suggest an excess of $z\gtrsim10$ galaxy candidates above most theoretical models. Here, we explore how the interplay between halo formation timescales, star formation efficiency and dust attenuation affects the…
We present measurements of the rest-frame ultraviolet luminosity function (UVLF) in three redshift bins over $z\sim5.5$-14 from the JWST COSMOS-Web survey. Our samples, selected using the dropout technique in the HST/ACS F814W, JWST/NIRCam…
The discovery of massive, high redshift galaxies with the James Webb Space Telescope (JWST) has been argued to challenge $\Lambda$CDM (cold dark matter): such systems would require extremely rare halos and baryon-to-stellar-mass conversion…
The so-called `impossibly early galaxy' problem, first identified via the Hubble Space Telescope's observation of galaxies at redshifts z > 10, appears to have been exacerbated by the more recent James Webb Space Telescope (JWST) discovery…
In their recent study, Labb\'e et al. used multi-band infrared images captured by the James Webb Space Telescope (JWST) to discover a population of red massive galaxies that formed approximately 600 million years after the Big Bang. The…
Observations with the {\it James Webb Space Telescope} have revealed a high abundance of bright galaxies at redshift, $z\gtrsim 12$, which has been widely interpreted as conflicting with the $\Lambda$CDM model. In Cowley et al. (2018)…
The high-redshift galaxy UV luminosity function (UVLF) has become essential for understanding the formation and evolution of the first galaxies. Yet, UVLFs only measure galaxy abundances, giving rise to a degeneracy between the mean galaxy…
Recently James Webb Space Telescope (JWST) have observed an excess of luminous galaxies at high redshifts ($z \gtrsim 10$). In this work, we investigate whether supermassive primordial black holes (SMPBHs) can explain it by their influence…
JWST observations have revealed an overabundance of bright galaxies at $z \geq 9$, creating apparent tensions with theoretical predictions within standard $\Lambda$CDM cosmology. We address this challenge using a semi-empirical approach…
In its first two years of operation, the James Webb Space Telescope has enabled the discovery of a surprising number of UV-bright galaxies at $z\sim10-14$. Their number density is still relatively uncertain, due to cosmic variance effects,…
We present compelling arguments -- focusing on galaxy science -- for preserving the main imagers and operational modes of the Hubble Space Telescope (HST) for as long as is technically feasible, to assure maximum complementarity to the…
We show that the rest-frame UV statistics and global properties of galaxies at 7 <= z <= 14 are naturally reproduced within the standard {\Lambda}CDM framework when galaxy formation is modeled with UniverseMachine applied to the…
We calculate the abundance of UV-bright galaxies in the presence of ultralight axion (ULA) dark matter (DM), finding that axions suppress their formation with a non-trivial dependence on redshift and luminosity. We set limits on axion DM…
Observations of the early universe at redshifts of order 10, collected during the last several years presented by the Hubble Space Telescope (HST) and recent data by the James Webb Space telescope (JWST) created strong doubts on the…
The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z>~7…
The James Webb Space Telescope has discovered high luminosity galaxies that appear to be "too many" and "too massive" compared to predictions of the Standard LCDM cosmology, suggesting that star formation in the early universe is more rapid…
Next generation observatories will enable us to study the first billion years of our Universe in unprecedented detail. Foremost among these are 21-cm interferometry with the HERA and the SKA, and high-$z$ galaxy observations with the James…