Measuring peculiar velocity and tomographic redshift dipole with DESI DR1 catalogs
Abstract
The so-called ``cosmic dipole tension'' challenges the Cosmological Principle by positing a discrepancy between the Solar System's peculiar velocity inferred from the Cosmic Microwave Background (CMB) dipole and that derived from large-scale structure number-count dipoles. Here we provide a high-precision determination of the kinematic dipole using the redshift-dipole method applied to the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). By exploiting the Doppler-induced modulation of observed redshifts, this estimator is intrinsically less sensitive to imaging systematics and selection-function uncertainties that can bias traditional number-count measurements. We conduct a tomographic analysis of four tracer populations, Bright Galaxy Sample, Luminous Red Galaxies, Emission Line Galaxies, and quasars, spanning 0.1<z<2.1. Survey geometry and statistical uncertainties are quantified using 1,000 \texttt{EZmock} realizations. We find that the high-redshift QSO sample implies a peculiar velocity of v = 357.95−48.47+55.05 km s−1, in excellent agreement with the CMB-inferred value of 369.82 ± 0.11 km s−1. By contrast, a complementary number-count analysis yields a significantly enhanced dipole amplitude, which we attribute to leakage of large-scale power and to incompleteness within the DESI DR1 footprint. These results indicate that the redshift dipole provides a cleaner and more reliable probe of the kinematic rest frame, offering strong support for the standard kinematic interpretation at high redshift and helping to resolve the apparent dipole anomaly.
Versions
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BibTeX
@misc{wu2026measuring,
title = {{Measuring peculiar velocity and tomographic redshift dipole with DESI DR1 catalogs}},
author = {Yi-Wen Wu and Jun-Qing Xia},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.30914},
eprint = {2608.30914},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.30914},
}
RIS
TY - UNPB
TI - Measuring peculiar velocity and tomographic redshift dipole with DESI DR1 catalogs
AU - Yi-Wen Wu
AU - Jun-Qing Xia
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2608.30914
UR - https://arxiv.org/abs/2608.30914
AB - The so-called ``cosmic dipole tension'' challenges the Cosmological Principle by positing a discrepancy between the Solar System's peculiar velocity inferred from the Cosmic Microwave Background (CMB) dipole and that derived from large-scale structure number-count dipoles. Here we provide a high-precision determination of the kinematic dipole using the redshift-dipole method applied to the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). By exploiting the Doppler-induced modulation of observed redshifts, this estimator is intrinsically less sensitive to imaging systematics and selection-function uncertainties that can bias traditional number-count measurements. We conduct a tomographic analysis of four tracer populations, Bright Galaxy Sample, Luminous Red Galaxies, Emission Line Galaxies, and quasars, spanning 0.1<z<2.1. Survey geometry and statistical uncertainties are quantified using 1,000 \texttt{EZmock} realizations. We find that the high-redshift QSO sample implies a peculiar velocity of v = 357.95_−48.47^+55.05 km s^−1, in excellent agreement with the CMB-inferred value of 369.82 ± 0.11 km s^−1. By contrast, a complementary number-count analysis yields a significantly enhanced dipole amplitude, which we attribute to leakage of large-scale power and to incompleteness within the DESI DR1 footprint. These results indicate that the redshift dipole provides a cleaner and more reliable probe of the kinematic rest frame, offering strong support for the standard kinematic interpretation at high redshift and helping to resolve the apparent dipole anomaly.
ER -