And it is a statistical hitch, and involves two otherwise highly reliable and oft used methods giving contradictory answers at nearly the same significance level! Does this mean that the chances are actually 50-50? Really, we need a bona fide statistician to take a look and point out the errors of our ways..

The first time around, Voss & Nelemans (arXiv:0802.2082) looked at how many X-ray sources there were around the candidate progenitor of SN2007on (they also looked at 4 more galaxies that hosted Type Ia SNe and that had X-ray data taken prior to the event, but didn’t find any other candidates), and estimated the probability of chance coincidence with the optical position. When you expect 2.2 X-ray sources/arcmin² near the optical source, the probability of finding one within 1.3 arcsec is tiny, and in fact is around 0.3%. This result has since been reported in Nature.

However, Roelofs et al. (arXiv:0802.2097) went about getting better optical positions and doing better bore-sighting, and as a result, they measured the the X-ray position accurately and also carried out Monte Carlo simulations to estimate the error on the measured location. And they concluded that the actual separation, given the measurement error in the location, is too large to be a chance coincidence, 1.18±0.27 arcsec. The probability that the two locations are the same of finding offsets in the observed range is ~1% [see Tom's clarifying comment below].

Well now, ain’t that a nice pickle?

To recap: there are so few X-ray sources in the vicinity of the supernova that anything close to its optical position cannot be a coincidence, BUT, the measured error in the position of the X-ray source is not copacetic with the optical position. So the question for statisticians now: which argument do you believe? Or is there a way to reconcile these two calculations?

Oh, and just to complicate matters, the X-ray source that was present 4 years ago had disappeared when looked for in December, as one would expect if it was indeed the progenitor. But on the other hand, a lot of things can happen in 4 years, even with astronomical sources, so that doesn’t really confirm a physical link.

Abstract:
The Digital Universe is a 3-D, interactive atlas of the universe created and distributed by the American Museum of Natural History and the Hayden Planetarium. The atlas is freely available on the web and is distributed to our business partners for use in full-dome video planetariums worldwide. The atlas is also utilized in pre-rendered content for Space Shows and Science Bulletins, a video program that brings subscribers the latest developments in astrophysics.
At the heart of the Digital Universe is scientific data visualization, where accuracy, not art, is our top priority. We use a variety of tools to render scientific data including Partiview, an open- source visualization tool, and Uniview, a full-dome package created in collaboration with students from Linkoping University and SCISS, AB in Sweden. Uniview allows for the seamless exploration of scales ranging from the mountains on Earth to the farthest known quasars. Uniview also provides for network collaboration for remote lectures, teaching, and professional development within a global network of users who log into the same database.

During my talk, I will demonstrate the Digital Universe atlas, discuss some of the visualization issues we encounter while building the atlas, then, in workshop-style, focus on how to use Partiview to visualize your own observed and simulated data.