Detecting floating black holes as they traverse the gas disk of the Milky Way

Abstract

A population of intermediate-mass black holes (BHs) is predicted to be freely floating in the Milky Way (MW) halo, due to gravitational wave recoil, ejection from triple BH systems, or tidal stripping in the dwarf galaxies that merged to make the MW. As these BHs traverse the gaseous MW disk, a bow shock forms, producing detectable radio and mm/sub-mm synchrotron emission from accelerated electrons. We calculate the synchrotron flux to be $\sim 0.01-10\mathrm{mJy}$ at GHz frequency, detectable by Jansky Very Large Array, and $\sim 10-100\mu \mathrm{Jy}$ at $\sim 10^{10}-10^{12}\mathrm{Hz}$ frequencies, detectable by Atacama Large Millimeter/sub-millimter Array. The discovery of the floating BH population will provide insights on the formation and merger history of the MW as well as on the evolution of massive BHs in the early Universe.

4 pages, 3 figures, including an additional constraint on the maximum Lorentz factor of the emitting electrons

References in corpus (5)

• Advection-Dominated Accretion and the Black Hole Event Horizon
• Wandering Black Holes in Bright Disk Galaxy Halos
• Effects of gravitational-wave recoil on the dynamics and growth of supermassive black holes
• Star Clusters Around Recoiled Black Holes in the Milky Way Halo
• A Population of Relic Intermediate-Mass Black Holes in the Halo of the Milky Way

Cited by in corpus (2)

• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• Illuminating Massive Black Holes With White Dwarfs: Orbital Dynamics and High Energy Transients from Tidal Interactions