  Biological active matter is typically tightly coupled to chemical reaction
networks affecting its assembly-disassembly dynamics and stress generation. We
show that localized states can emerge spontaneously if assembly of active
matter is regulated by chemical species that are advected with flows resulting
from gradients in the active stress. The mechanochemical localized patterns
form via a subcritical bifurcation and for parameter values for which patterns
do not exist in absence of the advective coupling. Our work identifies a
generic mechanism underlying localized cellular patterns.
