See you again: an 80∘ NGC~5466 stellar stream and its constraints on the Galactic dark halo mass
Abstract
Using \textit{Gaia} Data Release 3 combined with Dark Energy Spectroscopic Instrument Legacy Imaging Survey Data Release 9 and Panoramic Survey Telescope and Rapid Response System Data Release 2, we apply a modified matched filter method to obtain a weighted stellar map in the surrounding of the globular cluster NGC~5466. Our results support that the tidal stream of NGC~5466 extends around 80∘ on the sky, and the leading tail seemingly exhibits an upward deviation in the range of 180∘ ≲ α≲ 190∘, which supports previous claim that the Large Magellanic Cloud (LMC) may have caused dynamical perturbations to the stream. Based on the 308 highly-weighted member candidates of the NGC~5466 stream, we try to measure the mass distribution of the Milky Way dark matter halo along with the mass of LMC. By comparing the observed stream candidate members to a series of model streams generated under different potential parameters, we obtain the posterior distributions of the parameters: the circular velocity at the solar radius Vc = 239.56+1.46−1.44 km s−1, the density flattening of the halo q = 1.08+0.07−0.07, the scale radius of the halo density profile rs = 12.97+3.02−2.18 kpc and the total mass of the LMC MLMC = 9.63+1.89−2.00× 1010 M⊙. The enclosed mass of the Milky Way within the stream apocenter radius of ∼ 50 kpc is calculated as MMW(<50 kpc) = 4.59+0.48−0.37 × 1011 M⊙.
Related
- Reconciling Galactic rotation curve constraints with stellar stream modeling
- When Streams Curve Away: a Test of Dark Matter from Extragalactic Stellar Stream Populations
- Potamides: Mapping Dark Matter Halo Shapes from Stellar Stream Tracks in the Local Universe
- Impact of LSST systematics on stellar-stream density fluctuations for dark matter
- Constraints on Galactic Dark Photons from a DALI Prototype
BibTeX
@misc{bai2026again,
title = {{See you again: an $80^\circ$ NGC~5466 stellar stream and its constraints on the Galactic dark halo mass}},
author = {Di Bai and Yong Yang and Jing-Kun Zhao and Xian-Hao Ye and Gang Zhao},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02653},
eprint = {2611.02653},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02653},
}
RIS
TY - UNPB
TI - See you again: an 80^∘ NGC~5466 stellar stream and its constraints on the Galactic dark halo mass
AU - Di Bai
AU - Yong Yang
AU - Jing-Kun Zhao
AU - Xian-Hao Ye
AU - Gang Zhao
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02653
UR - https://arxiv.org/abs/2611.02653
AB - Using \textit{Gaia} Data Release 3 combined with Dark Energy Spectroscopic Instrument Legacy Imaging Survey Data Release 9 and Panoramic Survey Telescope and Rapid Response System Data Release 2, we apply a modified matched filter method to obtain a weighted stellar map in the surrounding of the globular cluster NGC~5466. Our results support that the tidal stream of NGC~5466 extends around 80^∘ on the sky, and the leading tail seemingly exhibits an upward deviation in the range of 180^∘ ≲ α≲ 190^∘, which supports previous claim that the Large Magellanic Cloud (LMC) may have caused dynamical perturbations to the stream. Based on the 308 highly-weighted member candidates of the NGC~5466 stream, we try to measure the mass distribution of the Milky Way dark matter halo along with the mass of LMC. By comparing the observed stream candidate members to a series of model streams generated under different potential parameters, we obtain the posterior distributions of the parameters: the circular velocity at the solar radius V_c = 239.56^+1.46_−1.44 km s^−1, the density flattening of the halo q = 1.08^+0.07_−0.07, the scale radius of the halo density profile r_s = 12.97^+3.02_−2.18 kpc and the total mass of the LMC M_LMC = 9.63^+1.89_−2.00× 10^10 M_⊙. The enclosed mass of the Milky Way within the stream apocenter radius of ∼ 50 kpc is calculated as M_MW(<50 kpc) = 4.59^+0.48_−0.37 × 10^11 M_⊙.
ER -