I am a postdoctoral researcher at the Institut de Física d'Altes Energies (IFAE) in Barcelona. My research revolves around a broad range of topics in Cosmology and Astrophysics, including the galaxy-halo connection, Lyman alpha forest, active galactic nuclei, photometric redshifts, and cross-correlation of cosmic probes. My principal lines of work are:

  1. The lensing-is-low problem. It is now widely recognized that simulation-based models optimized to fit the clustering of massive galaxies overestimate their gravitational lensing on small scales, which is commonly known as the "lensing-is-low problem." It has been proposed that this is just another face of the low-S8 tension, i.e., the discrepancy between early- and late-universe constraints on the amplitude of matter perturbations. However, I found that this problem reflects shortcomings of standard galaxy-halo connection models rather than tensions within the ΛCDM paradigm, and that it goes away when using more sophisticated models.

  2. Galaxy-halo connection. Thanks to the high-precision observations of ongoing and upcoming galaxy surveys, observational systematics and modeling shortcomings are progressively surpassing statistical errors as the primary source of uncertainty in large-scale structure studies. This problem is especially significant when attempting to extract cosmological information from small scales because statistical errors are very small in this regime, while non-linear couplings induced by gravity and the influence of galaxy formation physics are the largest. I study the impact of galaxy formation effects such as assembly bias on cosmological observables and work on novel models to extract unbiased cosmological constraints from small scales.

  3. Missing baryons. A complete census of baryons in the late universe is challenging due to the intermediate temperate and rarefied character of intergalactic gas. However, the kinematic Sunyaev-Zel'dovich effect (kSZ) is ideally suited to detect these baryons, which refers to the Doppler boosting of CMB photons as these scatter off free electrons moving relative to the CMB rest frame. This is because this observable is sensitive to all free electrons, independently of the temperature and density of the medium in which these reside. I used the cross-correlation of the kSZ effect and angular redshift fluctuations to set tomographic constraints on the abundance, location, and properties of intergalactic gas.

  4. Lyman alpha forest. Quasars are the brightest persistent sources in the Universe, and thanks to their great luminosity, we can detect them even at very high redshifts. As quasar light travels towards us, it interacts with neutral hydrogen in the intergalactic medium, producing a series of absorption features commonly known as the Lyman alpha forest. Modeling this observable on small scales presents significant challenges due to its dependence on the properties of the intergalactic medium and the non-linear nature of gravity. Typically, it requires high-demanding hydrodynamical simulations. I work on building machine learning-based surrogate models to accelerate the predictions of these simulations. Additionally, I have experience in identifying quasars, measuring their redshifts, and estimating the masses of supermassive black holes.