Date: 22/06/2018 08:02:38
From: Tau.Neutrino
ID: 1242887
Subject: X-rays from deep space help track down the universe's missing matter

X-rays from deep space help track down the universe’s missing matter

Although it makes up everything we see and touch on a daily basis, ordinary (or baryonic) matter is relatively rare in the universe, and weirder still there seems to be a huge chunk of it missing.

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Date: 22/06/2018 13:16:18
From: mollwollfumble
ID: 1242949
Subject: re: X-rays from deep space help track down the universe's missing matter

Tau.Neutrino said:


X-rays from deep space help track down the universe’s missing matter

Although it makes up everything we see and touch on a daily basis, ordinary (or baryonic) matter is relatively rare in the universe, and weirder still there seems to be a huge chunk of it missing.

more…

> baryonic matter is relatively rare in the universe, and weirder still there seems to be a huge chunk of it missing.

Well, yes and no. It’s known to be gas. If we have a look at for instance the Bullet Cluster, we can see the gas.

> observations of the most distant objects have shown how the matter budget has changed over billions of years, but after a certain point in history astronomers lose track of a huge amount of it.

I didn’t know that.

I like this chart very much.

> Using ESA’s XMM-Newton X-ray space observatory, the team observed a quasar that lies more than 4 billion light-years away, over a total of 18 days between 2015 and 2017. By studying how the X-ray signals from the quasar are obscured during their long journey, astronomers can determine what kind of matter lies between it and us.

That’s an old old technique. As old as 1970, if not 1963.

> “After combing through the data, we succeeded at finding the signature of oxygen in the hot intergalactic gas between us and the distant quasar, at two different locations along the line of sight,” says Nicastro. “This is happening because there are huge reservoirs of material – including oxygen – lying there, and just in the amount we were expecting, so we finally can close the gap in the baryon budget of the universe.”

Nice work. Surprising that it took so long.

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