pith. sign in

hub

Co-formation of the Galactic disc and the stellar halo

12 Pith papers cite this work. Polarity classification is still indexing.

12 Pith papers citing it
abstract

Using a large sample of Main Sequence stars with 7-D measurements supplied by Gaia and SDSS, we study the kinematic properties of the local (within ~10 kpc from the Sun) stellar halo. We demonstrate that the halo's velocity ellipsoid evolves strongly with metallicity. At the low [Fe/H] end, the orbital anisotropy (the amount of motion in the radial direction compared to the tangential one) is mildly radial with 0.2<beta<0.4. However, for stars with [Fe/H]>-1.7 we measure extreme values of beta~0.9. Across the metallicity range considered, i.e. -3<[Fe/H]<-1, the stellar halo's spin is minimal, at the level of 20<v_theta (km/s) <30. Using a suite of cosmological zoom-in simulations of halo formation, we deduce that the observed acute anisotropy is inconsistent with the continuous accretion of dwarf satellites. Instead, we argue, the stellar debris in the inner halo were deposited in a major accretion event by a satellite with Mvir>10^10 Msun around the epoch of the Galactic disc formation, i.e. between 8 and 11 Gyr ago. The radical halo anisotropy is the result of the dramatic radialisation of the massive progenitor's orbit, amplified by the action of the growing disc.

hub tools

years

2026 11 2019 1

verdicts

UNVERDICTED 12

clear filters

representative citing papers

Applying Liouville's Theorem to Gaia Data

astro-ph.GA · 2019-07-01 · unverdicted · novelty 5.0

Phase-space density is recovered from Gaia data for M4 and disrupted streams by correcting entropy injection and minimizing stream entropy, enabling original mass inference via Liouville's theorem.

citing papers explorer

Showing 1 of 1 citing paper after filters.