Breaking baryon-cosmology degeneracy with the electron density power spectrum

Abstract

Uncertain feedback processes in galaxies affect the distribution of matter, currently limiting the power of weak lensing surveys. If we can identify cosmological statistics that are robust against these uncertainties, or constrain these effects by other means, then we can enhance the power of current and upcoming observations from weak lensing surveys such as DES, Euclid, the Rubin Observatory, and the Roman Space Telescope. In this work, we investigate the potential of the electron density auto-power spectrum as a robust probe of cosmology and baryonic feedback. We use a suite of (magneto-)hydrodynamic simulations from the CAMELS project and perform an idealized analysis to forecast statistical uncertainties on a limited set of cosmological and physically-motivated astrophysical parameters. We find that the electron number density auto-correlation, measurable through either kinematic Sunyaev-Zel'dovich observations or through Fast Radio Burst dispersion measures, provides tight constraints on Ω m and the mean baryon fraction in intermediate-mass halos, fbar . By obtaining an empirical measure for the associated systematic uncertainties, we find these constraints to be largely robust to differences in baryonic feedback models implemented in hydrodynamic simulations. We further discuss the main caveats associated with our analysis, and point out possible directions for future work.8 Here, M denotes the mass of the Sun. 9 https://arepo-code.org. 10 http://www.tapir.caltech.edu/~phopkins/Site/GIZMO.html. 11 The remaining cosmological parameters are fixed to Ω b = 0.049, h = 0.6711, ns = 0.9624 within ΛCDM.

Deciphering baryonic feedback with galaxy clusters

“…Cosmic gas is redistributed by baryonic physics that modulates the total matter distribution, making observations of its distribution particularly constraining on relevant baryonic physics [15]. Numerous programs [14,[16][17][18][19][20][21][22] have explored observations of the cosmic gas distribution to constrain modulations of matter clustering due to baryonic feedback, some of which [14,16] have been combined with weak gravitational lensing analyses, leading to different levels of improvements on cosmological constraints. Specifically, [16] employ the cross-correlation of thermal Sunyaev-Zel'dovich (tSZ) signal detected in the cosmic microwave background (CMB) and weak lensing shear.…”

“…We consider 9 and 8 Y500c bins for Magneticum and illustris-TNG respectively. The number of clusters in each bin is[138,74,54,37,20,17,5,2,2] and[42,23,24,9,7,2,1,2] respectively. For the Magneticum case, we have checked that reducing to 5 bins does not change the result.…”

Learning cosmology and clustering with cosmic graphs

“…We note that a model that is designed to be used with real data should pass this test at the level of simulations. This kind of tests are non trivial to succeed, and have been carried out in other previous works using CAMELS simulations with diverse levels of performance (Villaescusa-Navarro et al 2021b, 2022bVillanueva-Domingo et al 2021a;Nicola et al 2022;Shao et al 2022;Wadekar et al 2022).…”