TDCOSMO likelihood for Cobaya

This package provides the TDCOSMO likelihood as an external package for Cobaya. The hierarchical computation of the likelihood uses the hierArc package along with lenstronomy. An example notebook is included demonstrating how to use the package.

⚠️ The velocity dispersions of the SLACS lenses measured by SDSS using single-aperture spectroscopy have recently been shown to exhibit bias compared to IFU spectra obtained from Keck (Knabel et al. 2024). This bias will propagate to cosmological inference if these data are included in the analysis (tdcosmo/data/slacs_sdss_likelihood_processed.pkl in this repository). For this reason, I recommend avoiding the use of this likelihood. The likelihoods derived from the time delay data and from IFU-measured kinematics for nine of the SLACS lenses are safe to use (tdcosmo/data/tdcosmo7_likelihood_processed.pkl and tdcosmo/data/slacs_ifu_likelihood_processed.pkl respectively). This repository will be updated with any future likelihood for IFU-measured kinematics when so provided by the TDCOSMO collaboration.

Requirements

• hierArc = 1.1.2: install with pip or clone from repo
• lenstronomy >= 1.1.3: install with pip or clone from repo

References

Birrer et al. (2020). TDCOSMO IV: Hierarchical time-delay cosmography – joint inference of the Hubble constant and galaxy density profiles, Astronomy & Astrophysics, 643, A165, November 2020.

@article{Birrer:2020tax,
    author = "Birrer, S. and others",
    title = "{TDCOSMO - IV. Hierarchical time-delay cosmography \textendash{} joint inference 
              of the Hubble constant and galaxy density profiles}",
    eprint = "2007.02941",
    archivePrefix = "arXiv",
    primaryClass = "astro-ph.CO",
    doi = "10.1051/0004-6361/202038861",
    journal = "Astronomy \& Astrophysics",
    volume = "643",
    pages = "A165",
    year = "2020"
}

Hogg (2024). Constraints on dark energy from TDCOSMO & SLACS lenses, Monthly Notices of the Royal Astronomical Society: Letters, 528, 1, March 2024.

@article{Hogg:2023khs,
    author = "Hogg, Natalie B.",
    title = "{Constraints on dark energy from TDCOSMO~\& SLACS lenses}",
    eprint = "2310.11977",
    archivePrefix = "arXiv",
    primaryClass = "astro-ph.CO",
    doi = "10.1093/mnrasl/slae005",
    journal = "Monthly Notices of the Royal Astronomical Society: Letters",
    volume = "528",
    number = "1",
    pages = "L95--L100",
    year = "2024"
}