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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."
Why would you even bother posting if you havent even read the article?
Excuse the Unicode crap in my posts. That's an apostrophe, and slashdot is busted.
so you thought energy was matter? that, while true, is false.
CLI paste? paste.pr0.tips!
https://www.youtube.com/watch?... Fast Radio Bursts
Looks at the hardware challenges
"Published on Nov 6, 2015
Fast radio bursts (FRBs) are mysterious single pulses recently discovered in routine L-band pulsar searches. They are very brief (~milliseconds), and exhibit dispersion and spatial distribution which suggests large -- possibly cosmological -- distances. Although they probably occur at a rate of about 10,000/sky/day, they are quite difficult to find due to the very narrow field of view of suitably-equipped radio telescopes, and also due to the prevalence of interference at L-band. In this talk I will give an overview of instrumentation that has been developed to detect FRBs in large numbers and with better information (polarization, improved localization, etc.). In particular I will describe GBTrans, a new instrument we (VT, WVU, and NRAO) have developed at Green Bank for continuous real-time FRB searching, and plans for a new instrument called LASA (Large Array of Small Arrays), which would be purpose-built for this task. Both systems feature real-time continuous acquisition and analysis of about 400 MHz of L-band spectrum, using FPGAs to compute dynamic spectra and GPUs to search 1000s of possible dispersion signatures simultaneously. LASA would replace the GBTrans 20-m dish antenna with 2 m x 2 m arrays of 256 tightly-coupled crossed dipole antennas each, forming 16 independently-steerable beams simultaneously. This problem requires mitigation of copious interference from active users of the L-band spectrum, and I'll explain how we manage to do that in real time as well."
Facts are history now plebs have politics for religion on social media.
Yes, this had more to do with an energetic outburst from an older galaxy, perhaps large stars colliding
I wonder if there was any corresponding reading from the gravity wave monitor
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How can I believe you when you tell me what I don't want to hear?
well, you get the idea.
Why would you even bother posting if you havent even read the article?
Given the average attention span of people these days (which lasts for about one sentence), I dare to say he never realized there even were articles behind any posts.
There are fewer illiterates than people who can't read.
... if there's an alien message in that bean! something like:
From: Venus RP
To: Earth cientistis
Subject: Earth's Moon Problem
Mesasge: Please stop blocking our view of your cities full of naked women with your natural satellite.. We know that was created by purpose.
Good, now use that fast radio burst to help me find my keys and we'll drive out of here.
You are welcome on my lawn.
Indeed. I was hoping they'd declare they found fahrvergnugen.
Table-ized A.I.
It sounds like the perfect thing to find the missing socks from the dryer.
First, kudos to the new /. owners for not linking a Forbes/startswithabang (fartswithabang?) article.
Dark matter and dark energy were the missing mass of the universe. Yawn.
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". 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.
Socialism: a lie told by totalitarians and believed by fools.
Astronomers have known for years that the ordinary matter we see every day -- made up of protons, electrons, and neutrons -- can only make up a small fraction of the mass-energy density needed to explain the large-scale structure of the universe. This ordinary, or "baryonic" matter, makes up around 4% of the critical amount. Another 23% or so is "dark matter", which isn't made of protons, electrons or neutrons, but does exert gravitational forces like baryonic matter; and the remaining 73% or so is the very mysterious "dark energy", which acts sort of like anti-gravity.
When most scientists see the phrase "missing matter", they think of the "dark matter" portion of the universe -- the 23%.
But this new result gives us information on a portion of the 4%, the ordinary baryonic matter. We think it should make up 4% of the critical density because of the relative abundances of hydrogen, helium, and lithium which were produced soon after the Big Bang ... but when we add up the stuff that we can see with telescopes -- stars and gas -- we find only about 1% of the critical amount. So, about 3% of the baryons were hiding somewhere.
This new study looked at radio waves from an event in a very distant galaxy. Those radio waves had to traverse a very long distance to reach us. As they flew through space, IF that space had even very thin traces of gas, waves of some frequencies would travel just a bit faster than others. That dispersion in frequency acts to spread out the arrival of the radio waves by the time they reach the Earth. The astronomers mentioned here observed a small spread in arrival times and used to to figure out how much gas the waves must have encountered in between the galaxies. The result: just the right amount of gas to account for all those hidden baryons.
So, yes, this study found missing baryons. It did not produce any direct measurements of dark matter or dark energy. On the other hand, if we can pinpoint other fast radio bursts in the future and study their host galaxies, we may learn something about those other entities, too.
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
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.
We don't see the world as it is, we see it as we are.
-- Anais Nin
Sorry, you lost me after 'span'. What was that ag... oh, look at that. A bird!
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.
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The article shows a couple a couple embedded images whose resolution is at least 4x too low to be able to read them. This happens all too often on the modern webs. Authors can't care enough to check what they're doing. Such crap didn't happen in the "this site is optimized for 800x600" era, or in print media.
I was basically repeating/interpreting what the fine article said:
FRBs show a frequency-dependent dispersion, a delay in the radio signal caused by how much material it has gone through.
I believe interstellar dispersion of electromagnetic waves is caused by interactions with ionized interstellar medium. A quick Google(interstellar dispersion) brought up this page which gives a formula that relates the integral of electron density along the path of the signal to the dispersion of the signal. On that page they assume they know the density of interstellar medium inside our galaxy and use the dispersion of signals from pulsars to estimate their distance. In the FRB experiment they did it the other way around and used the known distance (using the red-shift of the source galaxy) and the dispersion to estimate the integral of the density. Integral measurements such as this usually give much more accurate results than point measurements.
If the interstellar medium were entirely made up of ionized hydrogen then knowing the electron density would give you the total density since there would be one proton for every electron. You need to add corrections because only about 70% of the interstellar medium is hydrogen so you need to estimate the number of neutrons. You also need to make a small correction since the interstellar medium is not 100% ionized.
The reason why the dispersion is related to the electron density is given, for example, in J. D. Jackson's Classical Electrodynamics where the dielectric "constant" (and hence the speed of light) is shown to be a function of the frequency. The electromagnetic wave causes the electrons to wiggle (just a little), the higher the frequency, the less wiggling so the higher frequencies are slowed down less than the lower frequencies. You can think of it like having an eccentricity in a front tire of your car that makes the steering wheel vibrate. When you go fast enough so the frequency of the oscillations is much greater then the resonant frequencies of the components then the amount of vibration you experience goes down because the direction reverses before things can move very far. In the interstellar medium each electron slows down the wave just a little and the total amount of slowing down is proportional to the number of electrons encountered.
Usually, the "closeness" of the electrons is not considered, instead the integrated electron density is used. But it is possible to calculate how close the electrons have to be to a line between the source and the receiver using what is called the 3-point function. The cross section of the volume that contributes to a fixed percentage of the signal will be roughly elliptical with the source and the receiver at each focus of the ellipse. Given the vast intergalactic distances involved, it will probably be extremely wide near the middle by any earthly standards but this width is independent of the calculation of the dispersion. I'd imagine the width would scale as sqrt(d * c * t) where d is the distance between the source and the receiver, c is the speed of light, and t is roughly the duration of the signal (more accurately, the inverse of the bandwidth). The reason the closeness (the width of the 3-point function) doesn't matter is because the more spread out the 3-point function is, the weaker it is. All that matters is what you get when you sum it all up.
We don't see the world as it is, we see it as we are.
-- Anais Nin
Why would you even bother posting if you havent even read the article?
These things have articles?
Wanna buy a shirt?
https://www.redbubble.com/people/stealthfinger/shop?asc=u
Thank you. Asked and answered.
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Follow the grant money.
>>The mass of the universe universe is 70% dark energy, 25% dark matter, 5% familiar matter.
>Correct.
Once again I get nostalgic for the good old days, when a hypothesis dressed up as a theory wasn't taken for gospel. So, how many heretics will be burned this week?
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
Science moved past the evidence of our unaided senses in the 1600s. If you don't believe what we see with telescopes of various kinds, you don't believe in much.
Do you also believe that quantum mechanics and general relativity are both conspiracies? Or is 100 years enough time to get used to new ideas?
Socialism: a lie told by totalitarians and believed by fools.
Is that around the same time when people learned about a topic before making braod assertions about what is hypothesis and what is evidence based theory? Having evidence doesn't make something right, but it makes it kind of stupid looking to waste your time complaining that said evidence doesn't exist, as if you didn't know of any actual criticisms to give.