2025/04/14 by Xiao, Yun-Ao, Zou, Hu, Feng, Lu +8
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2504.09964
We utilize the DESI Legacy Imaging Surveys DR10 to investigate the previously undetected faint extension of the Palomar 5 stellar stream. By applying the HDBSCAN clustering algorithm, we identify stream members and successfully extend the leading arm of the stream to approximately DEC ∼ -15^∘. Combining the fully detected stream with a suite of mock stream simulations, we conduct a detailed comparison to constrain both the intrinsic properties of the stream and the dynamical parameters of the Milky Way (MW) halo. Our analysis yields a best-fit model characterized by eight parameters: Mhalo = 5.67×1011 M\odot, rs,halo = 28.94 kpc, qz = 0.93, Mgc = 4.31×103 M\odot, dMgc/dt = 1.81 M\odot Myr-1, μαcosδ= -2.28 mas yr-1, μδ = -2.26 mas yr-1, and D = 23.25 kpc. Notably, our constraints on the halo shape indicate that the MW's dark matter halo exhibits a flattened potential, with a minor-to-major axis ratio of qz = 0.93. This finding aligns well with theoretical expectations and previous observational estimates. Additionally, the best-fit model accurately reproduces the observed stream morphology and dynamics, providing a more precise understanding of both the evolution of the stream and the overall structure of the Galactic halo.