Search for topological defect dark matter with a global network of
  optical magnetometers
  Ultralight bosons such as axion-like particles are viable candidates for dark
matter. They can form stable, macroscopic field configurations in the form of
topological defects that could concentrate the dark matter density into many
distinct, compact spatial regions that are small compared to the galaxy but
much larger than the Earth. Here, we report the results of a search for
transient signals from axion-like particle domain walls with the Global Network
of Optical Magnetometers for Exotic physics searches (GNOME). We search the
data, consisting of correlated measurements from optical atomic magnetometers
located in laboratories all over the world, for patterns of signals propagating
through the network consistent with domain walls. The analysis of data from a
continuous month-long operation of the GNOME finds no statistically significant
signals, thus placing experimental constraints on such dark matter scenarios.
