Year: 2026
Type: article
Abstract: ABSTRACT We investigate how reliably the global properties of Milky Way-mass dark matter haloes can be recovered from dynamical data from a limited range of radii, particularly ${\lesssim} 30 \,\mathrm{kpc}$ where observations are most sensitive but baryonic processes modify the halo structure. Using the ARTEMIS (Assembly of high-ResoluTion Eagle simulations of MIlkyWay-type galaxieS) simulations, which produce varying degrees of baryon-induced contraction, we fit dark matter profiles over restricted radial ranges using commonly adopted parametric models. Assuming negligible observational uncertainties allows the systematic errors from these choices to be isolated. When fits are confined to inner radii, a Navarro–Frenk–White (NFW) profile underestimates the virial mass by a factor of ${\approx} 2$ on average (${\approx} 4$ for some systems), and the concentration by a factor of ${\approx} 2$. Einasto and generalized-NFW models provide excellent local fits but retain similar global biases. In contrast, a contracted halo prescription yields stable extrapolations and recovers unbiased halo mass estimates over all radii. The inferred mass improves systematically with increasing radial coverage, and tracers beyond ${\gtrsim} 50 \, \mathrm{kpc}$ largely eliminate the mean bias for all models. The local dark matter density at the Solar radius is recovered to within ${\lesssim} 5$% for all profiles other than NFW. These biases are sufficient to reconcile recent low Milky Way-mass estimates derived from inner rotation-curve analyses with the canonical ${\approx} 10^{12}\, \mathrm{M}_\odot$. We additionally find a halo-to-halo scatter of ${\gtrsim} 0.1$ dex (${\approx} 25$%) persists even under idealized conditions, setting a likely lower limit for the precision of halo mass estimates.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Awards: G1251748267, Durham DiRAC-2 petascale facility, G1468651527, DiRAC-2.5 - the pathway to DiRAC Phase 3, G1847476886, G2309215924, G2368581224, G2768788806, G2843074508, G3722612171, G4251892262, G429572867, G4831232377, DiRAC-2.5 DC - Operations 2017-2020, Large-scale structure cosmology and the thermal history of baryons, G6869467298, G720766788, G768801584, G7724874892, DiRAC: Memory Intensive 2.5y, Liverpool Centre for Doctoral Training for Innovation in Data Intensive Science, DiRAC: Memory Intensive 2.5x
OpenAlex ID: W7138172496