Joint analysis of the Macquart relation and the dispersion measure power spectrum: cross-covariance and redshift self-calibration
Abstract
The dispersion measures (DMs) of fast radio bursts (FRBs) trace ionised baryons along the line of sight, probing baryonic feedback. Two complementary observables can be constructed from an FRB catalogue: the DM-redshift (Macquart) relation of host-identified FRBs, and the angular power spectrum of the DM field of the full catalogue. Their joint analysis requires their cross-covariance. We derive it within the halo model and show it is a super-sample effect: only the monopole of an individual DM correlates with the angular power spectrum, yielding an exact, model-independent bound on the correlation coefficient. We validate the calculation against log-normal forward simulations of 104 FRBs. For individual DMs, the correlation with the bandpowers is at the per cent level. Neglecting the cross-covariance changes the width of the χ2 distribution by only 0.8 per cent, so the two observables can be treated as effectively independent for wide-area surveys. In a joint forecast with an LSST-like weak lensing survey, adding the Macquart relation tightens constraints on the physical baryon density by 32 per cent and on the mean host contribution by a factor of 4.1, while improving baryonification parameters by only about 5 per cent, indirectly through the host contribution. Finally, we show that the redshift distribution of FRBs without identified hosts, which enters every DM power spectrum, can be reconstructed by inverting their DMs with the jointly fitted mean relation without biasing the inferred parameters, whereas a 20 per cent error in the mean relation biases the DM power spectrum by up to 2σ per band for 5× 105 FRBs.
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BibTeX
@misc{wayland2026joint,
title = {{Joint analysis of the Macquart relation and the dispersion measure power spectrum: cross-covariance and redshift self-calibration}},
author = {Amy Wayland and Robert Reischke},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08481},
eprint = {2611.08481},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08481},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Joint analysis of the Macquart relation and the dispersion measure power spectrum: cross-covariance and redshift self-calibration
AU - Amy Wayland
AU - Robert Reischke
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08481
UR - https://arxiv.org/abs/2611.08481
AB - The dispersion measures (DMs) of fast radio bursts (FRBs) trace ionised baryons along the line of sight, probing baryonic feedback. Two complementary observables can be constructed from an FRB catalogue: the DM-redshift (Macquart) relation of host-identified FRBs, and the angular power spectrum of the DM field of the full catalogue. Their joint analysis requires their cross-covariance. We derive it within the halo model and show it is a super-sample effect: only the monopole of an individual DM correlates with the angular power spectrum, yielding an exact, model-independent bound on the correlation coefficient. We validate the calculation against log-normal forward simulations of 10^4 FRBs. For individual DMs, the correlation with the bandpowers is at the per cent level. Neglecting the cross-covariance changes the width of the χ^2 distribution by only 0.8 per cent, so the two observables can be treated as effectively independent for wide-area surveys. In a joint forecast with an LSST-like weak lensing survey, adding the Macquart relation tightens constraints on the physical baryon density by 32 per cent and on the mean host contribution by a factor of 4.1, while improving baryonification parameters by only about 5 per cent, indirectly through the host contribution. Finally, we show that the redshift distribution of FRBs without identified hosts, which enters every DM power spectrum, can be reconstructed by inverting their DMs with the jointly fitted mean relation without biasing the inferred parameters, whereas a 20 per cent error in the mean relation biases the DM power spectrum by up to 2σ per band for 5× 10^5 FRBs.
ER -