Massively parallel joint end-to-end Bayesian analysis of past, present, and future CMB experiments

Introduction

Detecting inflationary gravitational waves from the Big Bang and mapping cosmic structure formation rank among the most important goals in modern cosmology. Detailed cosmic microwave background (CMB) measurements are a uniquely powerful probe of these effects.

Challenges in Detection

However, the predicted signatures are tiny, and their detections require unprecedented instrumental sensitivity and systematics control.

Project Proposal

In this project, I propose to develop one single massively parallel end-to-end framework for the joint analysis of past, present, and future CMB experiments. This framework will be used to combine current data from:

1. WMAP
2. Planck LFI+HFI
3. Other existing experiments

Additionally, it will incorporate forthcoming measurements from the Simons Observatory (SO), all processed at the level of time-ordered data (TOD).

Future Preparations

I will also prepare for the analysis of future CMB experiments, including:

1. LiteBIRD
2. CMB-S4
3. A Voyage 2050 CMB spectral distortion probe

Technical Foundation

This framework will build on an Open Source Bayesian CMB Gibbs sampler called Commander, which has already played a transformational role in the field for more than two decades. It has recently been used successfully to derive new state-of-the-art frequency maps for both Planck LFI and WMAP.

Scalability Improvements

However, the existing code only scales well up to O(100) computing cores. In this project, I propose a new organization that will scale it up to O(100,000) cores, as required for next-generation experiments.

Systematic Corrections

I will also implement a wide range of ground-breaking TOD-level corrections for key systematic effects, including:

• Non-linear ADCs
• Cosmic ray glitches
• Atmospheric fluctuations
• Detector cross-correlations

These corrections will optimally exploit synergies between experiments.

Expected Outcomes

Once operational, I will use this global framework to:

• Establish a new state-of-the-art model of the microwave sky
• Shed new light on several hotly debated LCDM tensions
• Perhaps, make the world's first detection of primordial gravitational waves

Conclusion

This work represents a paradigm shift in the field of computational cosmology.