CMB-S4: Dark Radiation Anisotropy Flowdown Team (DRAFT) tool

Overview:

• Optimally combines data from different bands using noise + foreground signals in different bands.
  • Supports standard / constrained / partial internal linear combinations.
• Computes lensing noise curves using residual noise.
• Combines delensed CMB spectra and lensing spectra to forecast cosmological parameter constraints using Fisher formalism.
  • Delensing reference: Green, Meyers, van Engelen 2016, arXiv: 1609.08143.
  • Delensing + Fisher code reference: Hotinli, Meyers, Trendafilova, Green, van Engelen 2021, arXiv: 2111.15036.
    • Code repo.
  • Simple Fisher code repo without delensing.
• Estimates biases in cosmological parameters due to residual foregrounds also using Fisher formalism (yet to be integrated into this repo).
  • References: Huterer & Takada 2004, arXiv: 0412142; Loverde, Hui, & Gaztanaga 2006, arXiv: 0611539; Amara & Réfrégier 2007, arXiv: 0710.5171.

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Sub-modules and Dependencies:

1. CLASS_delens https://github.com/selimhotinli/class_delens (9944e0ec5f0b734b178436a8652b186046f63fdb)

This code uses a wrapper for the CLASS_delens code to facilitate Fisher forecasting of cosmological parameter constraints from CMB spectra.

Authors:

• Selim C. Hotinli, Joel Meyers, Cynthia Trendafilova, Daniel Green, Alexander van Engelen

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Cloning/CLASS installation:

Cloning:

1. Clone the repo first: git clone [email protected]:sriniraghunathan/CMB-S4_DRAFT.git
2. list the submodules: git submodule. This will show the CLASS_delens and the specific commit 9944e0ec5f0b734b178436a8652b186046f63fdb
3. pull the submodule: git submodule update --init --recursive

CLASS installation:

1. Install CLASS: cd CLASS_delens; make class
2. Ensure CLASS is working properly by running the following document within the CLASS_delens folder: ./class explanatory.ini

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Steps to run the code:

Parent script: perform_forecasts and this consists of two parts which can be run seprately as well.

1. ILC code: python3 get_ilc_weights_and_residuals.py -opfname results//s4_cmb_ilc.npy or look into this ilc code example notebook
2. Delensing + Fisher code (and this uses the outout from the previous step): python3 get_fisher_withdelensing.py -ilc_fname results//s4_cmb_ilc.npy -opfname results//s4_cmb_fisher.npy

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Results:

• Results are stored within results folder.
• Look into (read_ilc.py)[https://github.com/sriniraghunathan/CMB-S4_DRAFT/tree/main/results/read_ilc.py] to read the ILC residuals.
• Look into perform_forecasts to read the Fisher matrices.

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Contributors:

Joel Meyers, Cynthia Trendafilova, and Benjamin Wallisch.

Delensing and Fisher formalism contributions:

• Selim C. Hotinli, Joel Meyers, Cynthia Trendafilova, Daniel Green, Alexander van Engelen

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CMB-S4 instrument/noise specs:

• Chilean LAT: S4-Wide
• Delensing SouthPole LAT: S4-Ultra deep

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Foreground modelling:

• Extragalactic foregrounds: Radio, CIB, tSZ and kSZ power spectra from SPT measurements (George et al. 2015, arXiv: 1408.3161 and Reichardt et al. 2020, arXiv: 2002.06197).
  • Assumed polarisation fractions: CIB = 2%; Radio = 3%; tSZ/kSZ = 0. But these are configurable. Look into params.ini.
• Galactic foregrounds: Dust and Synchrotron power spectra obtained from pySM3 simulations.

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