CosmoBLENDER

Cosmological Biases to LENsing and Delensing Due to Extragalactic Radiation

CosmoBLENDER computes foreground-induced biases to temperature-based CMB lensing reconstructions, including:

• CMB lensing auto-correlations,
• CMB lensing cross-correlations with galaxies,
• internal B-mode delensing.

The implementation follows Baleato Lizancos et al. 2025.

Installation

From PyPI

pip install cosmoblender

From source (editable)

Clone the repository:

git clone https://github.com/abaleato/CosmoBLENDER.git

From the repository root, run:

pip install -e .

Dependencies

• NumPy, SciPy, Matplotlib, astropy
• BasicILC from this fork
• Hmvec from its galaxy branch for CIB calculations
• Quicklens (Python 3 version)
• pyccl (optional, for FFTlog-based calculations)

Notebooks

All tutorials and worked examples are in notebooks/.

Start with notebooks/example_pipeline.ipynb.

• notebooks/example_pipeline.ipynb: An introduction to data stuctures, experiment setup and bias calculations for auto-correlations, cross-correlations, and delensing.
• notebooks/auto_correlations.ipynb: Examples focused on biases to the CMB lensing auto-spectrum, including how to vary cosmological, astrophysical and experimental parameters.
• notebooks/cross_correlations.ipynb: Same as above, but focusing on cross-correlations with galaxy samples.
• notebooks/delensing.ipynb: Examples focused on foreground-induced biases in B-mode delensing.
• notebooks/varying_M_min.ipynb: Studies how predictions change as the minimum halo mass cut is varied.
• notebooks/varying_z.ipynb: Same as above, but for the redshift range.
• notebooks/explore_zerocrossing_primbispec.ipynb: Investigates where and why primary bispectrum contributions cross zero.

Attribution

If you use the code, please cite:

@ARTICLE{2025JCAP...11..031B,
             author = {{Baleato Lizancos}, A. and {Coulton}, W. and {Challinor}, A. and {Sherwin}, B.~D. and {Mehta}, Y.},
                title = "{A halo model of extragalactic contamination to CMB lensing, delensing, and cross-correlations}",
            journal = {\jcap},
         keywords = {CMBR theory, gravitational lensing, Sunyaev-Zeldovich effect, Cosmology and Nongalactic Astrophysics},
                 year = 2025,
                month = nov,
             volume = {2025},
             number = {11},
                    eid = {031},
                pages = {031},
                    doi = {10.1088/1475-7516/2025/11/031},
archivePrefix = {arXiv},
             eprint = {2507.03859},
 primaryClass = {astro-ph.CO},
}