Revisiting relaxation in globular clusters
Monthly Notices of the Royal Astronomical Society Oxford University Press 481:2 (2018) 2041-2061
Abstract:
The classical theory of cluster relaxation is unsatisfactory because it involves the Coulomb logarithm. The Balescu–Lenard (BL) equation provides a rigorous alternative that has no ill-defined parameter. Moreover, the BL equation, unlike classical theory, includes the cluster’s self-gravity. A heuristic argument is given that indicates that relaxation does not occur predominantly through two-particle scattering and is enhanced by self-gravity. The BL equation is adapted to a spherical system and used to estimate the flux through the action space of isochrone clusters with different velocity anisotropies. A range of fairly different secular behaviours is found depending on the fraction of radial orbits. Classical theory is also used to compute the corresponding classical fluxes. The BL and classical fluxes are very different because (a) the classical theory materially underestimates the impact of large-scale collectively amplified fluctuations and (b) only the leading terms in an infinite sum for the BL flux are computed. A complete theory of cluster relaxation likely requires that the sum in the BL equation be decomposed into a sum over a finite number of small wavenumbers complemented by an integral over large wavenumbers analogous to classical theory.Correlations between age, kinematics, and chemistry as seen by the RAVE survey
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 477:4 (2018) 5612-5624
Improved distances and ages for stars common to TGAS and RAVE
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 477:4 (2018) 5279-5300
Is the Milky Way still breathing? RAVE–Gaia streaming motions
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 475:2 (2018) 2679-2696
Self-consistent modelling of our Galaxy with Gaia data
Proceedings of the International Astronomical Union Cambridge University Press 12 (2018) 111-118