Synopsis: Cosmological Hat Trick

Three major drawbacks to the ΛCDM dark matter model of the universe may be ameliorated if a proposed particle couples to dark matter and to neutrinos.

In their attempts to puzzle out the 95% of the universe that isn’t common old ordinary stuff, astrophysicists appear to be settling on a model for the unseen mass and energy called ΛCDM (shorthand for cosmological constant plus cold dark matter). The model has met with success for large-scale structures in the universe, but suffers from three shortcomings on smaller scales: observations show fewer faint, small galaxy-forming regions than predicted; ΛCDM predicts a different internal galactic distribution of dark matter than observed; and the largest and densest satellites of the Milky Way predicted by simulations haven’t been observed. Writing in Physical Review Letters, Laura van den Aarssen at the University of Hamburg, Germany, and colleagues propose a new kind of long-range interaction among dark matter particles that addresses all three problems in one go.

The core of the authors’ hypothesis is their suggestion that an as yet unknown lightweight particle, which mediates the long-range interaction, couples to both dark matter particles and neutrinos. Such particles would induce velocity-dependent interactions between dark matter particles that, in the authors’ modeling, takes away more dark matter at galactic cores, consistent with observations, and resolves the questions of how smaller galaxies could form.

While much more work is needed to flesh out this framework, the authors say that the hypothesized particles may decay into neutrinos with energy around 1 tera-electron-volt, and if so, this signature might be detectable with future observations of the Milky Way by the IceCube neutrino detector at the South Pole. – David Voss


Features

More Features »

Subject Areas

Particles and FieldsAstrophysicsCosmology

Previous Synopsis

Chemical Physics

Testing the (Heavier) Waters

Read More »

Next Synopsis

Atomic and Molecular Physics

Downsizing Optical Lattices

Read More »

Related Articles

Synopsis: Restricting the Fifth Force
Gravitation

Synopsis: Restricting the Fifth Force

Observations of the orbits of two stars at the center of the Milky Way constrain gravitational models involving a hypothetical fifth force. Read More »

Synopsis: Blocking out Starlight
Astrophysics

Synopsis: Blocking out Starlight

A proposed telescope update could enable incoming light from multiple stars to be simultaneously blocked, making it easier to image exoplanets orbiting two or more stars. Read More »

Viewpoint: 3D View of a Comet’s Neighborhood
Astrophysics

Viewpoint: 3D View of a Comet’s Neighborhood

Detailed 3D simulations of a comet’s environment reveal the rich dynamics of ions and electrons observed by the Rosetta spacecraft around comet 67P. Read More »

More Articles