SPT-3G Data Products

SPT-3G D1 TT/TE/EE Bandpowers and Likelihood

This page provides data products associated with the SPT-3G D1 measurement of the CMB TT, TE, and EE power spectra, as described in Camphuis et al. (2025).

The released data include TT band powers spanning the angular multipole range 400 < ℓ < 3000, and TE/EE band powers covering 400 < ℓ < 4000. All spectra are binned into band powers of width Δℓ = 50. These data provide the most precise measurements of the TE and EE band powers at 2200 < ℓ < 4000, and 1800 < ℓ < 4000, respectively (at the time of release).

If you have any questions regarding this data set or its use, please contact Etienne Camphuis, Wei Quan, Lennart Balkenhol and Ali R. Khalife (etienne_dot_camphuis_at_iap_dot_fr, weiquan_at_uchicago_dot_edu, lennart_dot_balkenhol_at_iap_dot_fr, ridakhal_at_iap_dot_fr)

Bandpowers

We provide the foreground- and nuisance-subtracted minimum-variance combination of the SPT-3G D1 multi-frequency band powers for plotting purposes only, such as reproducing Figure 1 from Camphuis et al. (2025). The band powers, band power errors (both in Dℓ in units of μK2), and associated band centers are provided in 3 separate text files for TT, TE, and EE spectra, contained within the provided zip archive.

Likelihood Code

The likelihood code for the SPT-3G D1 TT, TE, and EE band powers is based on candl, a differentiable likelihood framework for analysing CMB power spectrum measurements.

We provide the SPT-3G D1 candl library at https://github.com/SouthPoleTelescope/spt_candl_data/tree/main, along with tutorial notebooks and sampler templates. Both the multi-frequency band powers likelihood code and the lite version of the likelihood code, called SPT-lite, are available.

MCMC Chains

We provide the main Markov Chains Monte Carlo (MCMC) used in the works of Camphuis et al. and Khalife et al. These include the following models: LCDM and its extensions with free lensing amplitude (A_L, A_recon, A_2pt), sum of neutrino mass (Mnu), effective number of relativistic degrees of freedom (Neff), helium fraction (Yp), Neff+Yp, spatial curvature (Omk), varying electron mass with Omk (Me+Omk), CPL model of Dark Energy (w0wa), a modified recombination model (ModRec) and Early Dark Energy (EDE).

We constrain each model with various combinations of the following datasets: SPT-3G D1 (with lensing from the MUSE analysis), ACTDR6 (with DR6 lensing), Planck PR3, Planck PR4 lensing, DESI DR2 BAO data and BAO data from SDSS.

Details are described in the paper and in an accompanying Readme.txt file included with the chains.