Dynamical Evidence of a Solitonic Core of $10^{9}M_\odot$ in the Milky Way

TL;DR

This paper provides evidence for a solitonic dark matter core in the Milky Way, consistent with wave-DM models predicting a dense bosonic core of about 10^9 solar masses within 100 parsecs.

Contribution

It presents observational evidence supporting the existence of a solitonic dark matter core in the Milky Way, aligning with wave-DM theoretical predictions.

Findings

Central star velocity dispersion peaks at ~130 km/s

Excess mass of ~1.5×10^9 solar masses within 100 pc

Supports boson mass of ~10^{-22} eV

Abstract

A wavelike solution for the non-relativistic universal dark matter (wave-DM) is rapidly gaining interest, following distinctive predictions of pioneering simulations of cosmic structure as an interference pattern of coherently oscillating bosons. A prominent solitonic standing wave is predicted at the center of every galaxy, representing the ground state, that has been identified with the wide, kpc scale dark cores of common dwarf-spheroidal galaxies, providing a boson mass of, $\simeq 10^{-22}$ eV. A denser soliton is predicted for Milky Way sized galaxies where momentum is higher, so the de Broglie scale of the soliton is smaller, $\simeq 100$ pc, of mass $\simeq 10^9 M_\odot$. Here we show the central motion of bulge stars in the Milky Way implies the presence of such a dark core, where the velocity dispersion rises inversely with radius to a maximum of $\simeq 130$ km/s, corresponding to an excess central mass of $\simeq 1.5\times 10^9 M_\odot$ within $\simeq 100$ pc, favouring a boson mass of $\simeq 10^{-22}$ eV. This quantitative agreement with such a unique and distinctive prediction is therefore strong evidence for a light bosonic solution to the long standing Dark Matter puzzle, such as the axions generic in String Theory.