In April, astronomers with the European Southern Observatory led by Christian Moni-Bidin of the University of Concepcion in Chile raised eyebrows by suggesting that our cosmic neighborhood is empty of the extra mass needed to hold the galaxy together. But researchers Jo Bovy and Scott Tremaine from the Institute for Advanced Study in Princeton, NJ, have submitted a paper claiming that the results reported by Moni Biden et al are “incorrect”, and based on an “invalid assumption” of the motions of stars within — and above — the plane of the galaxy.
The most popular current theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle. But several underground detectors searching for the elusive WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn't it been detected yet?
The ESO team, led by Christian Moni Bidin of the Universidad de Concepción in Chile, mapped over 400 stars near our Sun, spanning a region approximately 13,000 light-years in radius to estimate the mass of matter – visible and dark – in the sun's local neighborhood. . Their report identified a quantity of material that matched what could be directly observed: stars, gas, and dust… but no dark matter. “Our calculations show that it should have shown up very clearly in our measurements,” Bidin had stated, “but it was just not there!”
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