Archive for gamma ray

A Ghost of a Jet?

Posted in Astrohype, The Universe and Stuff with tags , , on June 4, 2012 by telescoper

Last week an article in Nature News caught my eye. Ghostly jets seen streaming from Milky Way’s core was the headline. It’s based on a paper by Su & Finkbeiner recently submitted to the arXiv. There’s even a picture showing the jets in glorious technicolour:

Wow! Impressive stuff. If the jets look like that it’s amazing nobody ever saw them before!

Oh, hang on. The picture is an “artist’s conception”. In other words, it’s what the jets might look like if they actually existed, as imagined by a bloke with a box of crayons.

And how strong is the evidence that they do exist? Here’s the last paragraph of the Nature article (my emphasis):

Although the emissions are dim and the observations don’t have the statistical significance that astronomers require for proof, Baganoff says that several properties make them compelling evidence of jets. They are brighter at higher γ-ray energies and also brighter than the surrounding interstellar medium. They also seem to be long and thin, as would be expected of jets. “Taking all of the evidence together, it appears highly plausible that the features are jets emanating from the Galactic Centre,“ he says.

If they “don’t have the statistical significance that astronomers require for proof” then one wonders why they’re being given so much publicity. In any case the “ghostly jets seen streaming from the Milky Way’s core” can’t be said to have really been “seen” for certain. But they are “highly plausible”. In other words, the authors would like them to be there.

All I can say is that it must have been a slow news day at Nature.

Still, nice drawing.