[essive]

Very strange to see this article posted now. This news from the AMS is over a year old. And clearly, there is considerable debate whether the positron excess is from dark matter particle annihilation or from nearby pulsars. There are many papers on the subject - here is just one example that explains some of the issues - http://arxiv.org/pdf/1304.1840.pdf (PS - I am an astronomy graduate student).

[ISL]

This article concerns a new data release from AMS -- 70% more statistics and a much wider energy range.

In the past, they've been careful to avoid saying whether or not the positron fraction flattens/rolls over at higher energy. These papers now give support to that conclusion, at moderate confidence levels.

[essive]

Excellent callout and my mistake missing the point on the wider energy range and the rollover. Thank you! The additional data will help the determination of dark matter vs. pulsars as the positron source.

"To determine if the observed new phenomenon is from dark matter or from astrophysical sources such as pulsars, AMS is now[sic] making measurements to determine the rate of decrease at which the positron fraction falls beyond the turning point (item 5), as well as to determine the antiproton fraction (the ratio of antiprotons to protons plus anti-protons). These will be reported in future publications."