Galactic X-rays originate from stars; Nearby cosmic rays

[n8allan]

Max-Planck-Institute: [url2=http://www.physorg.com/news160755456.html]Galactic X-ray emissions originate from stars[/url2]

A 25-year old astronomical mystery has been solved: Most of the diffuse X-ray emissions in the Milky Way do not originate from one single source but from so-called white dwarfs and from stars with active outer gas layers.

X-rays from regular old stars... pretty scandalous. There they go again with the "gas" thing. What kind of gas is it that emits X-rays?!

Goddard: Fermi telescope explores high-energy 'space invaders'
http://www.physorg.com/news160659605.html

What's most exciting about the Fermi, PAMELA, and H.E.S.S. data is that they may imply the presence of a nearby object that's beaming cosmic rays our way. "If these particles were emitted far away, they'd have lost a lot of their energy by the time they reached us," explained Luca Baldini, another Fermi collaborator at INFN.

If a nearby source is sending electrons and positrons toward us, the likely culprit is a pulsar -- the crushed, fast-spinning leftover of an exploded star. A more exotic possibility is on the table, too. The particles could arise from the annihilation of hypothetical particles that make-up so-called dark matter. This mysterious substance neither produces nor impedes light and reveals itself only by its gravitational effects.

"Fermi's next step is to look for changes in the cosmic-ray electron flux in different parts of the sky," Latronico said. "If there is a nearby source, that search will help us unravel where to begin looking for it."

Perhaps this is another chance for the EU community to make predictions. What will be the big shocker? Cosmic rays coming from nearby "ordinary" stars?

Best,

-Nate

[StevenO]

Again an article full of assumptions:

First they acknowledge plasma as the source:

Energetic X-ray emissions usually originate from very hot gases in a temperature range between 10 and 100 million degrees Celsius. And this "Galactic Ridge X-ray Emission" (GRXE) is also typical for very hot, optically thin plasma.

only to dismiss it:

A gas with these thermal properties would, however, immediately escape from our galaxy - the Milky Way would continuously lose colossal amounts of energy and finally collapse as the existing energy sources, such as stars and supernovae, would not be sufficient to replenish such a loss.

and to come back with the usual assumptions about accretion disks:

Since then, it has been assumed that a large portion of the GRXE originates from individual stars.

Most of the 473 X-ray sources are probably white dwarfs, which accrete matter from their surroundings, as well as stars with high activity in their outermost gas layer, the corona.

So, how many assumptions are that on top of eachother and is that "outermost gas layer" a plasma or not ?

[solrey]

I think the nearby cosmic rays are generated by the double layer of the heliosheath. The solar system/heliosphere should be surrounded by a toroidal ring current. I predict that the source of the cosmic rays will be rather homogenous from all directions, except for an equatorial belt that would be void of those particles, but denser along the edges of the belt. The whole pattern might look like a short, wide hourglass. That is if our instruments are capable of that level of detail.