A new paper in Nature offers further information about Fast Radio Bursts (FRBs), which we last looked at only a few days back. The February 24 post examined work on FRBs that were consistent with what has been seen before — transient pulses lasting mere milliseconds, while emitting huge amounts of energy (see Fast Radio Bursts: First Distance Measurement). Now we have further work out of the Max Planck Institute for Radio Astronomy (MPIfR) in Germany that describes the detection of the first source of repeating bursts, an object outside our own galaxy that is producing multiple short bursts.
Lead author Laura Spitler (MPIfR) explains that a McGill University graduate student named Paul Scholz, using data from the Arecibo radio telescope in Puerto Rico, discovered the repeat signals last November. Scholz found a total of 10 new bursts. “Not only does this source repeat, but the brightness and spectra of the bursts also differs from those of other FRBs,” adds Spitler. We may be looking at a new class of FRB, one perhaps drawing on extremely powerful flare activity in a rotating neutron star.
Image: The 305-m Arecibo telescope and its suspended support platform of radio receivers is shown amid a starry night in this artist’s impression. From space, a sequence of millisecond-duration radio flashes are racing towards the dish, where they will be reflected and detected by the radio receivers. Such radio signals are called Fast Radio Bursts, and Arecibo is the first telescope to see repeat bursts from the same source. Credit: Danielle Futselaar.
This MPIfR news release also points to an upcoming paper in Monthly Notices of the Royal Astronomical Society, which reports on a repeating FRB signature found by the Parkes radio telescope in Australia. Although not yet published, the preprint of this work is available, from which this:
Among the new FRBs is the largest excess DM [dispersion measure, the integrated free electron density along the line of sight] to date giving a redshift limit of <1.3. For the first time structure has been seen in the profile of FRBs with a two-component detection. This poses significant challenges to many of the models of FRB emission which rely on one-off high energy events. However the Cordes & Wasserman (2015) model of “supergiant” pulses and the Popov & Postnov (2007) model of hyperflares could both account for this structure. The rates expected by these models is highly uncertain and cannot at present be used as a discriminator.
A word on the term ‘dispersion measure,’ as found above. It is possible to distinguish a pulse from man-made interference because electrons in the interstellar medium cause radio waves to travel more slowly at lower radio frequencies. You’ll note above that the dispersion measure in the new observations is said to be the largest to date. All ten of the newly discovered bursts have a far higher dispersion measure than would be found in a source within our galaxy.
So now we have a bit of a conundrum. The work discussed here on the 24th was also produced by researchers at the Max Planck Institute for Radio Astronomy and likewise published in Nature. It focused on FRBs as cataclysmic events like gamma-ray bursts, which would not generate repeat occurrences. Now we are talking about a repeating FRB that results from an extragalactic neutron star. The implication: There are multiple ways to produce an FRB.
The plan going forward is to use interferometry to study the origins of these radio bursts. Jason Hessels (University of Amsterdam), a corresponding author on the Nature paper, notes the possibilities:
“Once we have precisely localized the repeater’s position on the sky, we will be able to compare observations from optical and X-ray telescopes and see if there is a galaxy there. Finding the host galaxy of this source is critical to understanding its properties.”
I may have the exact number wrong and probably do, but at best the number of FRBs thus far detected is still tiny — I make out 32 events so far. At any rate, each new event has the potential for revising our understanding of these unusual phenomena.
The paper is Spitler et al,, “A repeating fast radio burst,” published online by Nature 02 March 2016 (abstract). The upcoming MNRAS paper is Champion et al., “Five new Fast Radio Bursts from the HTRU high latitude survey: first evidence for two-component bursts.” submitted to Monthly Notices of the Royal Astronomical Society (preprint).
what is the DM of the new repeating burst? ( i believe they were all uniform)
is it a multiple of 187.5 ?
if so, case closed, it’s a message from non humans get over it.
It is pretty close to a multiple (3), but some of the recently reported ones were not. 130628 was 2.5, 130729 was 4.6, and 110423 was 3.3, so maybe that whole business is falling apart.
I hope that Jill Tarter is now SATISFIED with the natural extragalactic source scenario.
This seems to be a great discory. If I am understanding this correctly, the dispersion measure is different than before, therefor it is NOT a multiple of 187.5, meaning it is at a different distance to the frb source. I can’t wait to see more data come available in the coming months.
I am all thumbs regarding the math and astronomy, but I wonder if this source is lined up with our orbit?
That might suggest that they detected Earth through the transit method.
http://news.discovery.com/space/alien-life-exoplanets/seeking-the-aliens-who-are-looking-right-at-us-160301.htm
No, it’s at a declination of just over 33 degrees, do doesn’t line up with the ecliptic. I don’t think any responsible parties are convinced that the FRBs are artificial.
I interviewed the corresponding author on the Nature paper, Jason Hessels, this morning:
http://www.wowsignalpodcast.com/2016/03/burst-14-jason-hessels-on-repeating.html
From this video clip you can see the time to consolidation is quite quick ~8 millisecond, which is about the time of the blips, Neutron stars are most likely the culprits. The double blips could be from a fast spinning pulsar merging with a normal neutron star, it could have been spun up by stealing mass from the other star as it was dying.
http://www.ukaff.ac.uk/movies/nsmerger/
The short bursts of radio frequency are not bursts of noise but are radio signals that carry with them information about the universe through which they have has passed. This information, impressed on the FRBs can be thought of the sediment of the universe sampled over billions of years. An FRB duration is typically 4 milliseconds much of this duration is probably due the spreading ( dispersion) of the FRB along the journey from its source . This implies that the initial radio frequency pulse was short perhaps 100 micro Seconds or less. This short impulse cannot be created by an object of greater than 100 to 1000kM across. The magnitude of the original FRB energy prior to dispersion points to a generating mechanism of stellar or cosmic magnitude; one means of resolving this inconsistency will be to invoke a region of reverse dispersion close to the origin of the initial pulse. Note that reverse dispersion is encountered in fibre optics where it is employed in long distance communication to maintain signal bandwidth.
The coherence of the narrow band FRB Radio frequency pulse would appear to be consistent with energy storage at the microwave resonant frequency of the hydrogen ion. Such a mechanism is similar to that employed in early masers. A sphere of ionised hydrogen proposed as part of the mechanism for nuclear synthesis around a black hole or supernova core collapse would incorporate an abundant energy source, the sphere would have the potential for resonant microwave energy storage until energy density rises to a level to causes “Q” collapse due to non linearity. Under the core collapse FRB hypothesis every FRB will owe its origin to a supernova.
If the supernova and microwave resonance hypothesis is valid then of Part of FRB dispersion could be traced to the passage of the initial radio frequency pulse through the collapsing ionised shell. The unexplained mathematical relationship and the quantised nature of FRB pulse dispersion could then be partly due to the relationship of the shell thickness and the stages of nuclear synthesis following core collapse.
Exciting to see continued interest, the sphere of ionized material created by gravitational collapse would be a natural form of Dyson sphere capable of energy storage and rotation give rise to variable transmission.
(Tabbys Star?)
Obscure Cosmic Radio Phenomenon –“May Unveil Unexplained Existence of Dark Matter”
August 25, 2016
http://www.dailygalaxy.com/my_weblog/2016/08/obscure-cosmic-phenomenon-may-unveil-unexplained-existence-of-dark-matter.html
And this new announcement of a galaxy called Dragonfly 44 made up almost entirely of what is being called dark matter – might this also be what a Kardashev Type 3 civilization looks like, if their stars are surrounded by Dyson Shells/Swarms:
http://www.gemini.edu/node/12559
Here’s the preprint (came out in June), which is far more informative than the press release: http://arxiv.org/abs/1606.06291
I did a little more digging, and the position given for Dragonfly 44 in an earlier paper ( http://arxiv.org/abs/1504.03320 ) is : ? = 13h00m58.0s; ? = 26?58?35??.
Looking on Aladin, there are lots of WISE and 2MASS sources around that position, but not right there. I would think that if this was a galaxy with tons of IR excess, it would show up there. It’s a low redshift, so relatively close.