Dark matter may finally have been driven out of its hiding place. Scientists report seeing as many as 67 events of dark matter detection at the Cresst Experiment in Italy. This is the startling news coming out of the ongoing 7-day Topics in Astroparticle and Underground Physics Meetingin Germany. The announcement was made yesterday, i.e. on the 6th of September.
The events have been detected with a four-sigma confidence level, or with about 99.994% confidence. For the status of a discovery, the detection has to be at a five-sigma confidence level or at 99.99994% confidence. Thus, we may say that the signals are extremely strong, but not strong enough to warrant a discovery.
What is Dark Matter?
Dark Matter has been predicted to occupy 24% of the Universe, with ordinary matter occupying just 4-5%. The challenge in detecting dark matter is due to the fact that it interacts really weakly with matter (hence, its name). It was introduced into the theoretical framework to explain the rapid spinning of the galactic arms. It soon turned out that fine-tuned Dark Energy Models are needed to explain Cosmic Microwave Background Radiation and Gravitational Lensing.
Dark Matter particles must have mass. Thus, the constituent particles of dark matter are called broadly as Weakly Interacting Massive Particles’ or WIMPs. The Cresst experiment uses supercooled calcium tungstate crystals to search for dark matter particle. When a dark matter particle hits one of the crystals, it scintillates and the detectors can pick up that pulse of radiation and measure the energy of the collision.
While this is great news for most gravitational models, it doesn’t reconcile with the non-detection of dark matter events in the CDMS-II and XENON100 experiments, both of which are also searching for Dark Matter particles. The fact that the detection is not at a 5-sigma confidence level yet means that all hopes of reconciliation are not gone.
Dark Matter may finally have been smoked out of its hiding place, but we’re still not sure of that.