[Paper Review] The Circumgalactic Medium from the CAMELS Simulations: Forecasting Constraints on Feedback Processes from Future Sunyaev-Zeldovich Observations

Mark Vogelsberger, E. Barry Moser+11 more|arXiv (Cornell University)|Jul 10, 2022

Astrophysics and Cosmic PhenomenaPhysics and Astronomy108 references31 citations

TL;DR

This study forecasts constraints on galaxy feedback processes in the circumgalactic medium (CGM) using future Sunyaev-Zeldovich (SZ) observations, leveraging the CAMELS simulations to build an emulator of tSZ and kSZ profiles across varied feedback parameters. It finds that upcoming experiments like the Simons Observatory can constrain four key feedback parameters to within 10%, with inner radial profiles contributing most to constraining power, though current simulations still underpredict observed SZ signals.

ABSTRACT

It is important to understand the cycle of baryons through the circumgalactic medium (CGM) in the context of galaxy formation and evolution. In this study, we forecast constraints on the feedback processes heating the CGM with current and future Sunyaev-Zeldovich (SZ) observations. To constrain these processes, we use a suite of cosmological simulations, the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS). CAMELS varies four different feedback parameters of two previously existing hydrodynamical simulations, IllustrisTNG and SIMBA. We capture the dependences of SZ radial profiles on these feedback parameters with an emulator, calculate their derivatives, and forecast future constraints on these feedback parameters from upcoming experiments. We find that for a galaxy sample similar to what would be obtained with the Dark Energy Spectroscopic Instrument at the Simons Observatory, all four feedback parameters can be constrained (some within the 10% level), indicating that future observations will be able to further restrict the parameter space for these subgrid models. Given the modeled galaxy sample and forecasted errors in this work, we find that the inner SZ profiles contribute more to the constraining power than the outer profiles. Finally, we find that, despite the wide range of parameter variation in active galactic feedback in the CAMELS simulation suite, we cannot reproduce the thermal SZ signal of galaxies selected by the Baryon Oscillation Spectroscopic Survey as measured by the Atacama Cosmology Telescope.

Motivation & Objective

• To forecast how future Sunyaev-Zeldovich (SZ) observations will constrain feedback processes in the circumgalactic medium (CGM).
• To quantify the constraining power of tSZ and kSZ profiles on four astrophysical feedback parameters from the CAMELS simulation suite.
• To assess the relative contribution of inner versus outer radial profiles to parameter constraints.
• To evaluate the ability of CAMELS simulations to reproduce observed SZ signals from ACT and the Baryon Oscillation Spectroscopic Survey.

Proposed method

• Utilizes the CAMELS simulation suite, which varies four feedback parameters in IllustrisTNG and SIMBA hydrodynamical simulations.
• Constructs an emulator to model the dependence of tSZ and kSZ radial profiles on these feedback parameters.
• Calculates derivatives of the profiles with respect to each feedback parameter to enable Fisher forecasting.
• Performs Fisher analysis using forecasted error bars from the Simons Observatory and ACT, testing both Gaussian and real beam convolutions.
• Compares simulated SZ profiles to observed tSZ and kSZ signals from the Atacama Cosmology Telescope and BOSS.
• Combines constraints from tSZ and kSZ to assess joint sensitivity to feedback physics.

Experimental results

Research questions

• RQ1 Can future SZ observations constrain the four key feedback parameters in the CGM to within 10%?
• RQ2 Which radial component of the SZ profile—inner or outer—contributes more to parameter constraints?
• RQ3 To what extent can the CAMELS simulations reproduce observed tSZ and kSZ signals from real surveys like ACT and BOSS?
• RQ4 How do beam convolution effects (Gaussian vs. ACT beam) impact forecasted parameter constraints?
• RQ5 What feedback parameter combinations in CAMELS best match current observed SZ profiles?

Key findings

• Future observations from the Simons Observatory, combined with a DESI-like galaxy sample, can constrain all four feedback parameters to within 10% accuracy.
• The inner radial profile (inward of 3 arcminutes) contributes more to parameter constraints than the outer profile, due to higher signal-to-noise and central concentration of feedback effects.
• Forecasted constraints are tighter when using a Gaussian beam compared to the ACT beam, indicating beam resolution impacts sensitivity.
• Despite a wide range of AGN feedback parameter variation in CAMELS, the simulations still underpredict the observed tSZ signal from the Atacama Cosmology Telescope.
• The CAMELS-SIMBA model provides a better fit to observed tSZ profiles than the original IllustrisTNG simulation, but no model fully reproduces the data, indicating a need for improved feedback prescriptions.