New Fast Radio Burst Discovery Finds 'Missing Matter' In the Universe (phys.org)

According to a study published today, an international team of scientists has for the first time managed to identify the location of a fast radio burst. FRBs are bright radio flashes that generally last for a few milliseconds. While their origin is unknown, the results are a missing distribution of matter in the universe. Now, using a combination of radio and optical telescopes, scientists have found the FRB. According to Benjamin Stappers, Professor of Astrophysics at the University of Manchester, "Discovering more FRBs will allow us to do even more detailed studies of the missing matter and perhaps even study dark energy."

Comments

Re:I thought

[DrJimbo]

Nope. The mass of the universe universe is 70% dark energy, 25% dark matter, 5% familiar matter. But only about half of that 5% can be accounted for by direct observation - the rest is "missing".

Correct.

TFA claims that the radio burst let researchers find a very dim (radio) galaxy that would not have otherwise been found - the matter is "missing" simply because you have to point a very good telescope at exactly the right part of the sky for a long time to find it.

Incorrect. It doesn't even make sense that finding one more galaxy would somehow account for half the normal mass of the Universe. Finding the originating galaxy was part of the solution but it helped because it gave them the distance to the FRB source. They already knew the dispersion (different frequencies arriving at different times) of the FRB. The dispersion tells you how much non-dark matter the signal passed near during its trip here. By also knowing the distance to the source, they were able to calculate the average density of the non-dark matter along the line of travel. This average density was then be used to estimate the amount of non-dark matter in the Universe.

Re:I thought

[techno-vampire]

The dispersion tells you how much non-dark matter the signal passed near during its trip here.

I don't think that I ever knew enough physics to understand how the frequency dispersion works, but i was under the impression that it was caused by the signal going through a part of space where the density of matter was higher than average, not just by going near it. And, while I'm thinking about it, how near does it have to get in order to get this effect? I'm not saying that you're wrong, but I would appreciate a little clarification here.