fuzzy dark matter



physics, mathematical physics, philosophy of physics

Surveys, textbooks and lecture notes

theory (physics), model (physics)

experiment, measurement, computable physics

Fields and quanta

fields and particles in particle physics

and in the standard model of particle physics:

force field gauge bosons

scalar bosons

matter field fermions (spinors, Dirac fields)

flavors of fundamental fermions in the
standard model of particle physics:
generation of fermions1st generation2nd generation3d generation
quarks (qq)
up-typeup quark (uu)charm quark (cc)top quark (tt)
down-typedown quark (dd)strange quark (ss)bottom quark (bb)
neutralelectron neutrinomuon neutrinotau neutrino
bound states:
mesonslight mesons:
pion (udu d)
ρ-meson (udu d)
ω-meson (udu d)
ϕ-meson (ss¯s \bar s),
kaon, K*-meson (usu s, dsd s)
eta-meson (uu+dd+ssu u + d d + s s)

charmed heavy mesons:
D-meson (uc u c, dcd c, scs c)
J/ψ-meson (cc¯c \bar c)
bottom heavy mesons:
B-meson (qbq b)
ϒ-meson (bb¯b \bar b)
proton (uud)(u u d)
neutron (udd)(u d d)

(also: antiparticles)

effective particles

hadrons (bound states of the above quarks)


in grand unified theory

minimally extended supersymmetric standard model




dark matter candidates


auxiliary fields



A model for dark matter made up of massive but extremely light particles, whose de Broglie wavelength is at the scale of galaxies.

The idea is that on scales above that of galaxies, the predictions of fuzzy dark matter agree with the standard cold dark matter models that work exceptionally well on cosmological scales, while on scales of the size of galaxies the quantum properties of these light particles become relevant and change their effect just so as to fix the problems (see also MOND) that standard cold dark matter models have on these scales.

A natural candidate for such ultra-light particles are axions.

This kind of model was brought up independently by several groups of authors (see Lee 17 for historical survey) with early precursors going back as far as (Baldeschi-Gelmini-Ruffini 83), and accordingly goes by a number of different names, including the following:

and more.

The suggestion that fuzzy dark matter induces the observed almost-flat galactic rotation curves (“MOND”) seems to go back to (Sin 92). Further pointers are in (Lee 17, p. 3):

There are many works explaining the rotation curves of dwarf [17, 23, 69], and large galaxies [29, 43, 70–78] in this model.

More recently, detection of the 21cm hydrogen line from cosmic dawn indicates that star formation set in earlier than compatible with fuzzy dark matter models (Nebrin 17, Nebrin-Ghara-Mellema 18). This would rule out substantial contributions of fuzzy dark matter.



Early precursors of the idea include

The role of the Bose-Einstein condensate of axions on galactic scales was considered in

The proposal in the guise of “fuzzy dark matter” is originally due to

A detailed discussion is in

Review includes

Computer simulation of structure formation with fuzzy dark matter:

Some thoughts on the quantum measurement problem for fuzzy DM particles with huge macroscopic Compton wavelengths? is in

MOND Phenomenology

Discussion of how superfluid aspects of axionic fuzzy dark matter reproduce MOND phenomenology is in

Comparison and tension with experiment

Comparison to experiment (observation):

Strong constraints on fuzzy dark matter from observation of the cosmic 21cm hydrogen line are claimed and discussed in

Claim that the galaxy core-cusp problem is not resolved after all is discussed in

Claim that the fitting of the galaxy rotation curves is not resolved after all: