wolffem / aquinoruegacodecosmic_birefringencekomatsu

Cosmic Birefringence

Cosmic Birefringence

This code reproduces the results of Eskilt & Komatsu (2022) where Planck and WMAP polarization data are jointly sampled to measure the cosmic birefringence angle. The details behind the method of analysis can be found in

• Y. Minami et al., Progress of Theoretical and Experimental Physics 2019, 083E02 (2019), arXiv:1904.12440 [astro-ph.CO]
• Y. Minami and E. Komatsu, Progress of Theoretical and Experimental Physics 2020, 103E02 (2020), arXiv:2006.15982 [astro-ph.CO]
• Y. Minami and E. Komatsu, Phys. Rev. Lett. 125, 221301 (2020), arXiv:2011.11254 [astro-ph.CO]
• Diego-Palazuelos et al., Phys. Rev. Lett. 128, 091302 (2022), arXiv:2201.07682 [astro-ph.CO]
• J. R. Eskilt, A&A 662, A10 (2022), arXiv:2201.13347 [astro-ph.CO]

How Do I Run It?

There is a lot you need before being able to reproduce the results. Here, we outline all the steps that need to be done.

1) Getting the data

First, you need the Planck and WMAP maps. The detector split maps of Planck Data Release 4 (NPIPE) can be found on NERSC. Unfortunately, it does not seem like detector split maps are available on the Planck Legacy Archive.

The WMAP maps are available here: https://lambda.gsfc.nasa.gov/product/wmap/dr5/maps_da_r9_i_9yr_get.html

Second, you need beam transfer functions. For NPIPE, they are also avalable on NERSC. And for WMAP, they can be found here https://lambda.gsfc.nasa.gov/product/wmap/dr5/beam_xfer_get.html

Third, you need the masks. They can be found here: https://drive.google.com/file/d/1uZzBdv4eICmgWu7Kw7BXF6TioFY4S6FH/view?usp=sharing Put them in the generate_observed_power_spectra/masks folder. The sky fraction f_sky is already produced in the f.npy file. But feel free to double check.

2) Install PolSpice

Then you need to do the hardest part: Install PolSpice. http://www2.iap.fr/users/hivon/software/PolSpice/ I used version v03-07-03.

3) Get observed power spectra, psi_ell and LCDM spectra

Now, you need to run PolSpice. This is done through the file make_cl_files_polspice.py which runs through all combinations for both masks.

I highly recommend that you first only analyse HFI. This runs faster and is easier to debug. To do that, just switch from hfi_lfi_wmap_eb import maps_param to from hfi_eb import maps_param in make_cl_files_polspice.py. This needs to be done in beam_corrected_lcdm_spectra.py and correct_format_observed_cl.py as well. These parameter files can be found in the parameter_files folder. You need to give the parameter file the right path to the maps.

Once you have the observed power spectra in .dat files, you can generate psi_ell through the file calculate_psi_ell.py

Then you can run beam_corrected_lcdm_spectra.py and correct_format_observed_cl.py. These files generate the beam smoothed LCDM spectra and the observed spectra in file formats that cb.py can read. These files are stored in the pre_proc folder.

4) Run it!

Now you are ready to run it!

The file run_cosmic_birefringence_analysis.py runs the analysis on the two masks. As mentioned, please run HFI-only first. Doing Planck+WMAP takes time, so make sure that HFI-only works first.

Please also read the comments in run_cosmic_birefringence_analysis.py to get a better understanding of what the different parameters in the params variable do.

cb.py outputs a chain file in the chains folder that you are free to do all your analysis on. It also creates a corner plot that can be found in img/. If you let the analysis run on both masks, it outputs a file results.py that gives the mean and error bars of all sampled parameters.

Is something not working?

Please let me know if you run into any problems or if anything is unclear!

You can either open a GitHub issue, or contact me on [email protected]

Citation

Feel free to use the code as you see fit, but if you use it for published results, please cite

• J. R. Eskilt and E. Komatsu, Phys. Rev. D 106, 063503 (2022), arXiv:2205.13962 [astro-ph.CO]