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astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...
and
particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...
, self-interacting dark matter (SIDM) is an alternative class of
dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
particles which have strong interactions, in contrast to the standard
cold dark matter In cosmology and physics, cold dark matter (CDM) is a hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model, approximately 27% of the universe is dark matter and 68% is dark energy, with only a sm ...
model (CDM). SIDM was postulated in 2000 as a solution to the core-cusp problem. In the simplest models of DM self-interactions, a Yukawa-type potential and a force carrier φ mediates between two dark matter particles. On galactic scales, DM self-interaction leads to energy and momentum exchange between DM particles. Over cosmological time scales this results in isothermal cores in the central region of dark matter haloes. If the self-interacting dark matter is in
hydrostatic equilibrium In fluid mechanics, hydrostatic equilibrium, also called hydrostatic balance and hydrostasy, is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. I ...
, its pressure and density follow: :\nabla P_\chi/\rho_\chi = \nabla \Phi_ = \nabla (\Phi_\chi + \Phi_b) where \Phi_ and \Phi_ are the gravitational potential of the dark matter and a baryon respectively. The equation naturally correlates the dark matter distribution to that of the baryonic matter distribution. With this correlation, the self-interacting dark matter can explain phenomena such as the
Tully–Fisher relation In astronomy, the Tully–Fisher relation (TFR) is a widely verified empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its asymptotic rotation velocity or emission line width. Since the observed brightness of ...
. Self-interacting dark matter has also been postulated as an explanation for the DAMA annual modulation signal. commentar
The Possible First Signs of Self-interacting Dark Matter
/ref> Moreover, it is shown that it can serve the seed of
supermassive black holes A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (). Black holes are a class of astronomical o ...
at high redshift. SIDM may have originated in a so-called "Dark Big Bang". In July 2024 a study proposed SIDM solves the "final-parsec problem", two months later another study proposed the same with
fuzzy cold dark matter Fuzzy cold dark matter is a hypothetical form of cold dark matter proposed to solve the cuspy halo problem. It would consist of extremely light scalar particles with masses on the order of \approx 10^ eV; so a Compton wavelength on the order of 1 l ...
.


See also

* MACS J0025.4-1222, astronomical observations that constrain DM self-interaction * ESO 146-5, the core of Abell 3827 that was claimed as the first evidence of SIDM * Strongly interacting massive particle (SIMP), proposed to explain cosmic ray data *
Lambda-CDM model The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components: # a cosmological constant, denoted by lambda (Λ), associated with dark energy; # the postulated cold dark mat ...


References


Further reading

* * * {{Dark matter Astroparticle physics Dark matter