A possible detection of gas rotation in galaxy groups via the kinetic Sunyaev–Zeldovich effect
8 affiliations
- 1Astrophysics Research Institute, Liverpool John Moores University , Liverpool L3 5RF ,
- 2Institute for Astronomy, University of Edinburgh, Royal Observatory , Blackford Hill, Edinburgh EH9 3HJ ,
- 3Departamento de Física Teórica, Módulo 15, Facultad de Ciencias, Universidad Autónoma de Madrid , E-28049 Madrid ,
- 4Centro de Investigación Avanzada en Física Fundamental (CIAFF), Facultad de Ciencias, Universidad Autónoma de Madrid , E-28049 Madrid ,
- 5Department of Physics and Astronomy, University of the Western Cape , Bellville, Cape Town 7535 ,
- 6Department of Astronomy, University of Massachusetts , Amherst, MA 01003-9305 ,
- 7Department of Astronomy, University of Science and Technology of China , Hefei, Anhui 230026 ,
- 8State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University , Shanghai 201210 ,
Abstract
We utilize the kinetic Sunyaev–Zeldovich effect (kSZ) to measure the rotation of ionized gas within galaxy groups defined in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) galaxy sample, via their dipolar imprint on the cosmic microwave background (CMB). We estimate the direction of the projected angular momentum for each of our selected fast-rotating groups by measuring the redshift dipole of satellite galaxies around their group centres. We find a clear redshift dipole in the stacked data for the selected SDSS groups. We then perform oriented stacking of the Planck CMB temperature map using the group centres and directions of angular momenta. We report a 2.3σ tentative detection of the dipolar rotational kSZ effect (rkSZ) within the virial radii of our fast-rotating groups from SDSS with an average mass of 1014 h−1M⊙ (corresponding to a null-hypothesis probability of 0.96 per cent). We estimate the averaged rotational velocity of the sample to be ∼100 − 200 km s−1, reaching a maximum value of 158.8± 13.6 km s−1. Our results are consistent within the errors with predictions based on the ELUCID constrained realization simulation, with the predicted amplitude of the rkSZ signal being slightly lower near the centre. We also identify a systematic bias when estimating rotational velocities using the observed redshifts of galaxies, but find it to be subdominant for our analysis.
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BibTeX
@article{yang2026possible,
title = {{A possible detection of gas rotation in galaxy groups via the kinetic Sunyaev–Zeldovich effect}},
author = {Tianyi Yang and Yan-Chuan Cai and Weiguang Cui and John A Peacock and Romeel Davé and Houjun Mo and Huiyuan Wang and Xiaohu Yang},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag1943},
url = {https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1943/8914600},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A possible detection of gas rotation in galaxy groups via the kinetic Sunyaev–Zeldovich effect
AU - Tianyi Yang
AU - Yan-Chuan Cai
AU - Weiguang Cui
AU - John A Peacock
AU - Romeel Davé
AU - Houjun Mo
AU - Huiyuan Wang
AU - Xiaohu Yang
PY - 2026
DA - 2026/10/13
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag1943
UR - https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1943/8914600
AB - We utilize the kinetic Sunyaev–Zeldovich effect (kSZ) to measure the rotation of ionized gas within galaxy groups defined in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) galaxy sample, via their dipolar imprint on the cosmic microwave background (CMB). We estimate the direction of the projected angular momentum for each of our selected fast-rotating groups by measuring the redshift dipole of satellite galaxies around their group centres. We find a clear redshift dipole in the stacked data for the selected SDSS groups. We then perform oriented stacking of the Planck CMB temperature map using the group centres and directions of angular momenta. We report a 2.3σ tentative detection of the dipolar rotational kSZ effect (rkSZ) within the virial radii of our fast-rotating groups from SDSS with an average mass of 10^14 h^−1M_⊙ (corresponding to a null-hypothesis probability of 0.96 per cent). We estimate the averaged rotational velocity of the sample to be ∼100 − 200 km s^−1, reaching a maximum value of 158.8± 13.6 km s^−1. Our results are consistent within the errors with predictions based on the ELUCID constrained realization simulation, with the predicted amplitude of the rkSZ signal being slightly lower near the centre. We also identify a systematic bias when estimating rotational velocities using the observed redshifts of galaxies, but find it to be subdominant for our analysis.
SN - 0035-8711
SN - 1365-2966
ER -