Bayesian leave-one-out cross-validation for astrophysical model comparison using gravitational-wave background data

Fuente: arXiv
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Main Authors: Tiruvaskar, Shreyas, Gordon, Chris
Format: Preprint
Published: 2026
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author Tiruvaskar, Shreyas
Gordon, Chris
author_facet Tiruvaskar, Shreyas
Gordon, Chris
contents Previous work showed that ultralight-dark-matter solitons can provide dynamical friction for supermassive black-hole binaries, suppressing low-frequency power in the pulsar-timing-array gravitational-wave background and constraining the particle mass and effective ultralight-dark-matter fraction. Here we extend that analysis by comparing the predictive performance of four models: simplified and realistic ultralight-dark-matter implementations, a phenomenological environmental-hardening model, and a gravitational-wave-only model. We use Bayesian leave-one-out cross-validation on the five lowest pulsar-timing-array frequency bins. The phenomenological model gives the largest expected log predictive density, but its advantage over the other models is not large compared with the estimated standard errors. The current data therefore do not decisively prefer one model overall. The clearest pairwise result is within the ultralight-dark-matter framework: the simplified model outperforms the realistic implementation in all five frequency bins. Current pulsar-timing-array data are therefore compatible with ultralight-dark-matter-induced low-frequency suppression, but do not yet distinguish ultralight-dark-matter significantly from more generic environmental descriptions of supermassive-black-hole-binary evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05679
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Bayesian leave-one-out cross-validation for astrophysical model comparison using gravitational-wave background data
Tiruvaskar, Shreyas
Gordon, Chris
Cosmology and Nongalactic Astrophysics
Data Analysis, Statistics and Probability
Previous work showed that ultralight-dark-matter solitons can provide dynamical friction for supermassive black-hole binaries, suppressing low-frequency power in the pulsar-timing-array gravitational-wave background and constraining the particle mass and effective ultralight-dark-matter fraction. Here we extend that analysis by comparing the predictive performance of four models: simplified and realistic ultralight-dark-matter implementations, a phenomenological environmental-hardening model, and a gravitational-wave-only model. We use Bayesian leave-one-out cross-validation on the five lowest pulsar-timing-array frequency bins. The phenomenological model gives the largest expected log predictive density, but its advantage over the other models is not large compared with the estimated standard errors. The current data therefore do not decisively prefer one model overall. The clearest pairwise result is within the ultralight-dark-matter framework: the simplified model outperforms the realistic implementation in all five frequency bins. Current pulsar-timing-array data are therefore compatible with ultralight-dark-matter-induced low-frequency suppression, but do not yet distinguish ultralight-dark-matter significantly from more generic environmental descriptions of supermassive-black-hole-binary evolution.
title Bayesian leave-one-out cross-validation for astrophysical model comparison using gravitational-wave background data
topic Cosmology and Nongalactic Astrophysics
Data Analysis, Statistics and Probability
url https://arxiv.org/abs/2605.05679