# Mystery of strange radio bursts from space

Gold Member
DISCRETE STEPS IN DISPERSION MEASURES OF FAST RADIO BURSTS

5. CONCLUSION
We have noted a potential discrete spacing in DM (Dispersion Measures) of FRBs (Fast Radios Bursts). Identied steps are integer multiples of 187.5cm-3 pc, so that DMs occur in groups centered at 375, 562, 750, 937, 1125cm-3 pc, with errors <5%. If this holds, future FRBs would show DMs in these groups (and perhaps at the base 187.5cm-3 pc, or larger integer multiples beyond 1125cm-3 pc).
In case this would hold, an extragalactic origin would seem unlikely, as high (random) DMs would be added by intergalactic dust. A more likely option could be a galactic source producing quantized chirped signals, but this seems most surprising. If both of these options could be excluded, only an articial source (human or non-human) must be considered, particularly since most bursts have been observed in only one location (Parkes radio telescope). A re-assessment of man-made phenomena, such as perytons (Burke-Spolaor et al. 2011), would then be required. Failing some observational bias, the suggestive correlation with terrestrial time standards seems to nearly clinch the case for human association of these peculiar phenomena. In the end we only claim interesting features which further data will verify or refute.
(emphasis mine)

And no, this wasn't published in April 1st!

Link to New Scientist article: Is this ET? Mystery of strange radio bursts from space.

Garth

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Chronos
Gold Member
It certainly is ... interesting. It is difficult to resist concluding some pretty exotic technology is required to fine tune coordination between signals.

wabbit
Gold Member
Had a quick look - does it say substantially more w.r.t. the thread title than "we haven't looked very much into possible causes and we just don't know what this could be, so E.T. is one possibily we can entertain" ?

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Gold Member
I think it is saying a bit more than that, even though we have to remain sceptical until proven otherwise.

It would seem to be difficult to find a natural explanation, particularly because to the correlation of the dispersion measures with exact multiples of 187.5cm-3.

The only other possibility IMHO, as described in the paper, is that the signal is terrestrial "perytons" - wait we have a picture:-
- sorry, wrong kind of peryton!

Garth

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wabbit
marcus
Gold Member
Dearly Missed
Garth, I looked up an elementary explanation of the dispersion measure (DM) of pulsar signals and found this:
http://astronomy.swin.edu.au/cosmos/P/Pulsar+Dispersion+Measure

It explains why the DM can be quoted in parsecs per cubic cm, as in your article.

My impression was that the authors were leaning towards an artificial (terrestrial) origin. Particularly as almost all the instances were picked up at one observatory (Parkes), and because of the correlation with the Earthly time standard.
==quote==
As perytons are thought to be produced on Earth, this would imply that FRBs are also Earthly noise. Indeed, why would both perytons and FRBs show arrival times with a strong correlation to Earth’s integer second?

This hints at some man-made device, such as mobile phone base stations. The device needs to keep (or sync) the time to sub-second precision, ...

5. CONCLUSION

...
...
...
Failing some observational bias, the suggestive correlation with terrestrial time standards seems to nearly clinch the case for human association of these peculiar phenomena...
==endquote==

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wabbit
Hey guys,

Let me preface this by saying that I'm not a scientist, or a mathematician, in fact I'm pretty terrible at maths, but I have noticed a pattern between these 187.5 steps and π - is this something that is known already?

I thought I would query this before I go any further so as not to embarrass myself with my lack of understanding!

wabbit
Gold Member
Which pattern ?

In any case if any, it would then if not a coincidence (most likely, 3 or 4 digits only plus a range of possible pattern making transformations) perhaps point to a terrestrial origin from someone who knew in what unit DM would be measured - a practical joke on the observers ?

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Like I say, I don't have a understanding of the underlying principals, so I could be doing something stupid - but here is what I saw:

FRBs step in 187.5cm
Hydrogen Line 21cm

187.5 / 21 = 8.928
(2*Pi)* 1420.40 (Hydrogen line MHZ) = 8924.63 / 1000 = 8.924

375 / 21 = 17.857
(4*Pi)* 1420.40 (Hydrogen line MHZ) = 17849.27 / 1000 = 17.849

562/21 = 26.761
(6*Pi)* 1420.40 (Hydrogen line MHZ) = 26773.909/ 1000 = 26.773

750/21 = 35.714
(8*Pi)* 1420.40 (Hydrogen line MHZ) = 35698.54/ 1000 = 35.698

If I am doing something silly then please forgive my ignorance (and feel free to have a laugh at my expense!)

Gold Member
Like I say, I don't have a understanding of the underlying principals, so I could be doing something stupid - but here is what I saw:

FRBs step in 187.5cm
Hydrogen Line 21cm

187.5 / 21 = 8.928
(2*Pi)* 1420.40 (Hydrogen line MHZ) = 8924.63 / 1000 = 8.924

375 / 21 = 17.857
(4*Pi)* 1420.40 (Hydrogen line MHZ) = 17849.27 / 1000 = 17.849

562/21 = 26.761
(6*Pi)* 1420.40 (Hydrogen line MHZ) = 26773.909/ 1000 = 26.773

750/21 = 35.714
(8*Pi)* 1420.40 (Hydrogen line MHZ) = 35698.54/ 1000 = 35.698

If I am doing something silly then please forgive my ignorance (and feel free to have a laugh at my expense!)
Sorry Wizzyman - no "Hydrogen times Pi"

The wavelength and frequency of a transmission are related by $\lambda\nu = c$ so in your calculations you have used the fact that $2 \pi c = 2 \pi \lambda \nu = 188.365 \times10^9 cm.s^{-1}$ and this coincidentally is near the numerical value of the DM step of 187.5 cm-3 pc (not cm as you quote - in any case the units are all wrong).

A mistaken near coincidence!

Garth

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Gold Member
Garth, I looked up an elementary explanation of the dispersion measure (DM) of pulsar signals and found this:
http://astronomy.swin.edu.au/cosmos/P/Pulsar+Dispersion+Measure

It explains why the DM can be quoted in parsecs per cubic cm, as in your article.

My impression was that the authors were leaning towards an artificial (terrestrial) origin. Particularly as almost all the instances were picked up at one observatory (Parkes), and because of the correlation with the Earthly time standard.
==quote==
As perytons are thought to be produced on Earth, this would imply that FRBs are also Earthly noise. Indeed, why would both perytons and FRBs show arrival times with a strong correlation to Earth’s integer second?

This hints at some man-made device, such as mobile phone base stations. The device needs to keep (or sync) the time to sub-second precision, ...

5. CONCLUSION

...
...
...
Failing some observational bias, the suggestive correlation with terrestrial time standards seems to nearly clinch the case for human association of these peculiar phenomena...
==endquote==
Thank you for that link Marcus, but note that one signal was picked up at Arecibo.

Garth

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Sorry Wizzyman - no "Hydrogen times Pi"

The wavelength and frequency of a transmission are related by $\lambda\nu = c$ so in your calculations you have used the fact that $2 \pi c = 2 \pi \lambda \nu = 188.365 \times10^9 cm.s^{-1}$ and this coincidentally is near the numerical value of the DM step of 187.5 cm-3 pc (not cm as you quote - in any case the units are all wrong).

A mistaken near coincidence!

Garth
I'll just pretend that I understood all of that, back away slowly to the back of the class and put on the cap of shame. Thanks for setting me straight!

Gold Member
I think it is saying a bit more than that, even though we have to remain sceptical until proven otherwise.

It would seem to be difficult to find a natural explanation, particularly because to the correlation of the dispersion measures with exact multiples of 187.5cm-3.

The only other possibility IMHO, as described in the paper, is that the signal is terrestrial "perytons"

Garth
Another clue in today's physics arXiv Identifying the source of perytons at the Parkes radio telescope.

A reminder:
Perytons" are millisecond-duration transients of terrestrial origin, whose frequency-swept emission mimics the dispersion of an astrophysical pulse that has propagated through tenuous cold plasma. In fact, their similarity to FRB 010724 had previously cast a shadow over the interpretation of \fast radio bursts," which otherwise appear to be of extragalactic origin.
Identified:
Subsequent tests revealed that a peryton can be generated at 1.4 GHz when a microwave oven door is opened prematurely and the telescope is at an appropriate relative angle.
Somebody was cooking supper!!

However note:
Now that the peryton source has been identified, we furthermore demonstrate that the microwaves on site could not have caused FRB 010724. This and other distinct observational differences show that FRBs are excellent candidates for genuine extragalactic transients.
Curiouser and curiouser!!

Garth

OmCheeto and wabbit
mfb
Mentor
A microwave oven telescope!
"Hey, could you check if my lunch is ready?"
Now that the peryton source has been identified, we furthermore demonstrate that the microwaves on site could not have caused FRB 010724.
Okay, but with just one event the timing structure is meaningless.

wabbit
Gold Member
Maybe manufacturers should now put a warning sign on microwaves "beware of perytons - do not open during cooking" : )

OmCheeto
Gold Member

Katie Mack @AstroKatie · 12 hours ago
Fact Sheet: Perytons vs. Fast Radio Bursts (see http://arxiv.org/abs/1504.02165 ) #FRB #perytons

Thank you for clearing it up.

I was somewhat confused.

---------------------------------
Katie Mack
@AstroKatie
(a.k.a. Dr Katherine J Mack) astrophysicist, occasional freelance science writer, connoisseur of airplane food
Melbourne, Australia, or not
www.astrokatie.com

CalcNerd
Gold Member
According to this paper: Identifying the source of perytons at the Parkes radio telescope -
Radio emission escaping from microwave ovens during the magnetron shut-down phase neatly explain all of the observed properties of the peryton signals. Now that the peryton source has been identified, we furthermore demonstrate that the microwaves on site could not have caused FRB 010724. This and other distinct observational differences show that FRBs are excellent candidates for genuine extragalactic transients.
Perytons that have been observed are caused by a microwave. However at least one signal FRB 010724 was not such a peryton, which they still claim could be extraterrestrial.

Garth

wabbit
Gold Member
I don't know if this applies at all to 010724, but I just saw this in another thread :
He proposes an interesting candidate for some FRBs (121102 is the one quoted).

Gold Member
Yes, at last a natural explanation for non-terrestrial FRBs!

I found the FRB eprint/papers a bit confusing as to which signals might be non-terrestrial and which might be someone's microwaved supper!

If they are 'Planck stars', which is assuming such stars exist in the first place, then you still have to explain the 1875 multiples.

Garth

wabbit
Gold Member
If they are 'Planck stars', which is assuming such stars exist in the first place, then you still have to explain the 1875 multiples.
Garth
Ah I thought this concerned only the microwave perytons. As you say one needs to read closely to sort them out...
For Planck stars, if they (Rovelli & al.) can determine some unique enough signature of Planck star signals (didn't see that in the slides, only that FRBs could have the right wavelength - but from their earlier papers it seems the signal received from a Planck star should have a characteristic magnitude, spectrum, decay shape, etc., depending on just mass of star and distance) and if that does match some FRBs, this would be pretty big news.

Is there no sense in which the FRB's are directional. Like is there any pattern to where they are coming from? Or is that not a meaningful notion in practical radio astronomy...? Or did I just miss it.

Gold Member
Is there no sense in which the FRB's are directional. Like is there any pattern to where they are coming from? Or is that not a meaningful notion in practical radio astronomy...? Or did I just miss it.
Yes, I have wondered the same thing. Without checking further my guess would be that these signals are so brief that there has not been enough time for the radio telescopes to train in on them and get a bearing.

Garth

Yes, I have wondered the same thing. Without checking further my guess would be that these signals are so brief that there has not been enough time for the radio telescopes to train in on them and get a bearing.

Garth
Relates to a part of the search for signals from E.T that I am confused about. Is dissipation a well enough understood phenomenon in terms of the transmission possibilities and paths, to rule out the hypothesis that we haven't found them because they are likely highly local in origin, and otherwise well-damped. Or does our ability to sweep the sky (because it's good enough) eliminate those as possible explanations?

Is there no sense in which the FRB's are directional. Like is there any pattern to where they are coming from? Or is that not a meaningful notion in practical radio astronomy...? Or did I just miss it.
In order to get a directional fix the event would need to be simultaneously observed from at least two, and preferably 3, widely separated receivers.

Jimster41
wabbit
Gold Member
Ah I thought this concerned only the microwave perytons. As you say one needs to read closely to sort them out...
.
Went back to http://arxiv.org/abs/1503.05245 - nope, you're right, the Arecibo 121102 signal does fall in that patern.

Now the pattern is weaker though, since we appear to have (assuming I got this right)
(a) a bunch of pizzas or FRBs (unclear) at multiples of 187.5
(b) Parkes 010724 at 375
(c) Arecibo 121102 at 557

Might Arecibo also have a microwave on premises ? The plot thickens : )

In http://arxiv.org/abs/1504.02165 they say that FRBs (not just 010724) are _not_ perytons
We have thus demonstrated through strong evidence that
perytons and FRBs arise from disparate origins.
But this is all so confusing I ll just wait for their next release, or maybe the one after that.

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Cell phones?