From Hot Gas to Star Formation: Tracing the Baryonic Universe to Unmask Fundamental Physics

par Abhishek Maniyar (CNRS - LAPTh)

jeudi 2 avr. 2026, 11:00 → 12:00 Europe/Paris

Auditorium Vivargent (LAPTh)

The standard cosmological model provides a remarkable framework for understanding the dark universe, but the visible matter—baryons—introduces complex, non-linear astrophysics that precision cosmology can no longer afford to ignore. For instance, energetic baryonic feedback suppresses the matter power spectrum on small scales, creating a notorious degeneracy with the signatures of massive neutrinos. To break these degeneracies and fully unlock the potential of next-generation surveys, we must accurately map the thermodynamic and kinematic states of gas across cosmic history.

In this seminar, I will present a multi-probe approach to tracing the baryonic lifecycle, from diffuse hot gas to the dense sites of star formation. First, I will explore the hot, ionized universe using the thermal and kinematic Sunyaev-Zel'dovich (tSZ and kSZ) effects. I will present new Compton-$y$ maps constructed by combining high-resolution SPT-3G data with full-sky Planck observations, alongside recent kSZ measurements achieved through cross-correlation with the  dark energy survey (DES-Y6) galaxies.

Moving from the diffuse medium to galaxies themselves, I will demonstrate how the Cosmic Infrared Background (CIB) serves as a powerful tracer of obscured star formation. By cross-correlating the CIB with large-scale structure surveys, we can tightly constrain the cosmic Star Formation Rate Density and understand how star formation populates dark matter halos over time. Finally, time permitting, I will briefly highlight the emerging frontier of Line Intensity Mapping (LIM) as a novel tool for capturing the 3D distribution of the yet-unexplored high-redshift universe.