See you again: an 80^∘ NGC~5466 stellar stream and its constraints on the Galactic dark halo mass

Using 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_.