I present new cosmological fits to a Hubble diagram built from supernovae and a homogeneous quasar sample spanning a redshift interval z = 0.7--3.5. The quasar distances are derived from the non-linear relation between X-ray and UV luminosities, and the sample is selected to minimize dust reddening, gas obscuration, host-galaxy contamination, and selection biases as described in the companion...
The persistent discrepancy between the locally measured Hubble constant, derived from Cepheids and Type Ia supernovae, and the value inferred from the cosmic microwave background underscores the need for independent cosmological probes. Cosmic chronometers provide a direct, model-independent measurement of the expansion history, but their accuracy is currently limited by systematic...
Despite its remarkable success, the standard cosmological model, $\Lambda$CDM, faces several serious challenges. Among them, the “Hubble tension”—the discrepancy between the value of the Hubble constant inferred from observations of the early Universe and that obtained directly from local measurements—is one of the most important problems in modern cosmology. As a possible solution to this...
We study the clustering of an optically identified galaxy cluster catalogue from the fourth data release of the Kilo Degree Survey (KiDS-1000). The photometric sample was identified by the Adaptive Matched Identifier of Clustered Objects (AMICO) algorithm and consists of 9049 clusters with $S/N\geq3.5$, in redshift range $0.1\leq z<0.8$, spread over an effective area of 838.78 deg$^2$. They...
