Resurrection of the WIMP as DM candidate

[Chronos]

The case for WIMPS as dark matter has been stalled over the past few years, largely by controversial claims of detection. Here is a recent addition to the literature http://arxiv.org/abs/1401.3295, Search for An Annual Modulation in Three Years of CoGeNT Dark Matter Detector Data.

 

[marcus]

The case for WIMPS as dark matter has been stalled over the past few years, largely by controversial claims of detection. Here is a recent addition to the literature http://arxiv.org/abs/1401.3295, Search for An Annual Modulation in Three Years of CoGeNT Dark Matter Detector Data.

Good find! On page 5:

...and larger values of σSI relative to the ROIs in Fig. 8. This is a relevant region of parameter space [58, 59]. This particle would be invisible (most of its recoils below detector thresholds) during winter, producing signals six months later, when the Earth-halo relative velocity is at a maximum. ...​

From roughly the spring equinox to the fall equinox the Earth orbit velocity is "forwards" (with the solar system motion around center of galaxy).
The rotation planes are tilted 60 degrees, so orbit speed only contributes slightly to solar system speed. But still. It happens that around summer solstice the Earth orbit speed contributes the most to solar system motion in the galaxy. I would guess around cos 60 times 30 km/s ≈ 15 km/s.

And around winter solstice the overall speed would be around 15 km/s LESS than the average solar system speed, again due to Earth orbit velocity being slantwise backwards.

And they seem to be finding some annual variation in scintillations in their detectors. Exciting. I hope it is confirmed by other studies.