Synopsis: Sterile Neutrino as Dark Matter Candidate

A dark matter particle in the form of a noninteracting neutrino could explain the recent detection of an x-ray emission line from galaxy clusters.
Synopsis figure
A. Fabian (IoA Cambridge) et al. /NASA

A hypothetical neutrino that does not interact through the weak force could be the source of a recently detected x-ray emission line coming from galaxy clusters. However, previous models using this so-called “sterile” neutrino as a form of dark matter were not able to satisfy constraints from cosmological observations. Now, writing in Physical Review Letters, Kevork Abazajian of the University of California, Irvine, shows that a sterile neutrino with a mass of 7 kilo-electron-volts (keV) could be a viable dark matter candidate that both explains the new x-ray data and solves some long-standing problems in galaxy structure formation.

Cosmologists have long considered neutrinos as possible dark matter particles. However, because of their small mass (less than about 1 eV), conventional neutrinos are too fast, or “hot,” to form the dense dark matter structures needed to hold galaxies and galaxy clusters together. By contrast, sterile neutrinos, which result from certain neutrino theories, can have larger masses and could have been naturally produced in the big bang by neutrino flavor mixing.

The problem has been that sterile neutrinos should decay, producing an x-ray signal that no one has observed—until maybe now. Earlier in 2014, an analysis of galaxy cluster data revealed an x-ray emission line, which is consistent with the decay of a 7-keV sterile neutrino. Normally, dark matter with this mass would be too “warm” to match galaxy data. However, Abazajian showed that the sterile neutrinos could have a “cooler” momentum distribution if they were produced through resonantly enhanced neutrino flavor mixing (the MSW effect). When Abazajian plugged this neutrino into a cosmological model, he found it could explain both the small number of Milky Way satellite galaxies and their central densities, which have eluded the currently favored cold dark matter model. – Michael Schirber


More Announcements »

Subject Areas

Particles and FieldsAstrophysicsCosmology

Previous Synopsis

Next Synopsis

Materials Science

Sliding Sand

Read More »

Related Articles

Synopsis: Testing Gravity On Solar System Scales

Synopsis: Testing Gravity On Solar System Scales

A proposed space mission would precisely measure deviations from Newtonian gravity on a scale of 100 astronomical units. Read More »

Viewpoint: Connecting the Higgs Mass with Cosmic History

Viewpoint: Connecting the Higgs Mass with Cosmic History

A theoretical proposal ties the puzzling light mass of the Higgs particle to a hypothetical new particle that plays an important role during the big bang. Read More »

Synopsis: LHC Data Might Reveal Nature of Neutrinos
Particles and Fields

Synopsis: LHC Data Might Reveal Nature of Neutrinos

A long-standing question over whether the neutrino is its own antiparticle might be answered by looking at decays of W bosons. Read More »

More Articles