The mass distribution of cluster Abell 370. reconstructed through gravitational lensing, shows two large, diffuse halos of mass, consistent with dark matter with two merging clusters to create what we see here. Around and through every galaxy, cluster, and massive collection of normal matter exists 5 times as much dark matter, overall. But what is the nature of this dark matter? We still don’t know. (NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland), R. Massey (Durham University, UK), the Hubble SM4 ERO Team and ST-ECF)

Forget WIMPs, Axions And MACHOs: Could WIMPzillas Solve The Dark Matter Problem?

Our dark matter searches have yet to yield a robust detection. Could we be looking in all the wrong places?

There’s perhaps no more fundamental question to ask than, “what is the Universe made of?” What we see, directly, is dominated by normal matter: things made of particles we know well like protons, neutrons, and electrons, and the photons they emit. But our measurements of the largest structures in the Universe indicate that this is only 5% of what’s out there. The rest is dark matter and dark energy. While dark energy might be an inherent property of space itself, we assume, because of its gravitational effects, that dark matter clusters, clumps, and is made of particles.

Large scale projection through the Illustris volume at z=0, centered on the most massive cluster, 15 Mpc/h deep. Shows dark matter density (left) transitioning to gas density (right). The large-scale structure of the Universe cannot be explained without dark matter.(Illustris Collaboration / Illustris Simulation)

But what, exactly, is dark matter? And, moreover, can we be certain it exists? There are a huge suite of detectors and experiments out there searching for it, and yet no robust, verified, direct detection has ever been reported. There is no smoking gun we can point to and say, “this was an event caused by an interaction with dark matter.” The overwhelming majority of…