Signals from a spectacular neutron star merger that made gravitational waves are slowly fading away

May 1, 2018 by Tara Murphy And David Kaplan, The Conversation
Neutron star merger. Credit: NASA's Goddard Space Flight Center/CI Lab

Eight months ago, the detection of gravitational waves from a binary neutron star merger had us and other astronomers around the world rushing to observe one of the most energetic events in the universe.

What most people don't realise is that we continued to observe the event every few weeks from then up to now.

Our team started searching for radio emission from the merger, known as GW170817, making a detection two weeks after the August event. Now, the radio emission is starting to fade.

As we prepare to say goodbye (at least for now) to this incredible object, we reflect on what what we've learned so far, with our paper accepted for publication in the Astrophysical Journal.

The detection of gravitational waves and electromagnetic radiation (such as and radio waves) from the same object mean physicists have been able to:

  • confirm a prediction of general relativity that gravitational waves travel at the speed of light
  • figure out how matter behaves when you squeeze it harder than in the nucleus of an atom
  • explain where some of the gold (and other heavy elements) in the universe are produced
  • and start to solve a decades-old mystery about what causes short gamma-ray bursts.

Observing the merger

Radio telescopes such as the Australia Telescope Compact Array and the Jansky Very Large Array (in the United States) are designed to detect electromagnetic radiation with wavelengths from centimetres to metres.

Radio observations of GW170817 from two telescopes. The central bright object in each image is the host galaxy NGC 4993. The smaller bright spot in the crosshairs is the neutron star merger. Credit: David Kaplan. Data from Mooley et al. (2018), Nature, 554, 207, Author provided

Unlike visible light, radio waves travel through space almost unimpeded by dust. They can be detected during the day as well as at night: radio telescopes can observe around the clock.

The radio waves we detected have travelled 130 million light years from the galaxy NGC 4993 where the star merger took place.

When the two collided they emitted a burst of gamma rays shortly after, which was detected by the Fermi satellite 1.74 seconds after the . What happened next in the explosion is what we've all been trying to work out.

Within 12 hours astronomers had detected a bright, fading signal in visible light. We think this came from neutron star material flung out at 50% of the speed of light. It was glowing hot from a bunch of radioactive decays.

Neutron stars are the most dense objects we know of, except for black holes: imagine the Sun squashed into a region the size of a city.

Timelapse of the CSIRO’s Australia Telescope Compact Array. Credit: Alex Cherney (terrastro.com)

When two neutron stars collide they form a new object that has slightly less mass than the two original stars: in this case likely a new black hole. A tiny fraction of the mass is blasted out as both matter and energy (remember E=mc2) and that is what we detect on Earth.

What do radio waves tell us?

The radio emission we detected days later, though, is a different matter.

Radio waves are created when electrons are accelerated in magnetic fields. This happens at shock fronts in space, as material from stellar explosions crashes into the stuff around the star.

This stuff is called the interstellar medium and is about 10 quintillion times less dense than air on Earth (almost, but not quite, a vacuum). The nature of the tells us the details of this shock, which we can run backward in time to try to understand the explosion.

A simulation of a neutron-star merger giving rise to a broad outflow – a ‘cocoon’. A cocoon is the best explanation for the radio waves, gamma rays and X-rays the astronomers saw arising from the neutron-star merger GW170817.

One big question is whether there was a narrow jet of material moving at 99.99% of the speed of light that punched its way out of the explosion and hit the interstellar medium.

We think that these must happen in gamma-ray bursts: did that happen here?

What happened in the explosion?

We're still not sure of the details, but we don't think there was a successful jet in GW170817. That's because we have now observed the emission start to fade (the optical emission started to fade immediately).

This shows the explosion probably isn't a classic gamma-ray burst with relativistic jets, as shown in the figure below (left). What is more likely is that we are seeing a "cocoon" of material that has broken out from the explosion.

Models of what might be happening in the merger. Our data has shown the left option is unlikely, and the radio emission is probably caused by a cocoon of material (right). Credit: Kasliwal et al., Science (2017), Author provided

So where does this material come from?

The material flung out of the neutron (known as ejecta) was moving fast, about 50% of the speed of light. What if there was an even faster (99.99% of the speed of light) jet that happened soon after?

This jet could have blown a bubble in the ejecta, making it move faster (maybe 90% of the speed of light) and stopping the jet in its tracks: we call this a cocoon.

Saying goodbye (for now)

After eight months of watching GW170817 we know that it is different to anything we've seen before, and has behaved in completed unexpected ways.

Radio observations of the neutron star merger show that it is now fading. Credit: David Kaplan, Dougal Dobie. Data from Dobie et al. (2018), ApJL, Author provided

The is now fading, but this may not be the end of the story. Most models predict a long term afterglow from neutron star mergers, so GW170817 might reappear months or even years in the future.

In the meantime, we are waiting with anticipation for the Laser Interferometer Gravitational-Wave Observatory (LIGO) to start its next observing run early next year. We might even capture a new type of event, a neutron star merging with a black hole.

Explore further: Radio observations point to likely explanation for neutron-star merger phenomena

More information: arxiv.org/abs/1803.06853

Related Stories

Neutron-star merger yields new puzzle for astrophysicists

January 18, 2018

The afterglow from the distant neutron-star merger detected last August has continued to brighten - much to the surprise of astrophysicists studying the aftermath of the massive collision that took place about 138 million ...

Seeing the light of neutron star collisions

October 16, 2017

When two neutron stars collided on Aug. 17, a widespread search for electromagnetic radiation from the event led to observations of light from the afterglow of the explosion, finally connecting a gravitational-wave-producing ...

What are neutron stars?

October 16, 2017

Thrilled physicists and astronomers announced Monday the first-ever observation of the merger of two neutron stars, one of the most spectacularly violent phenomena in the Universe.

Recommended for you

Hunting molecules to find new planets

June 19, 2018

It's impossible to obtain direct images of exoplanets as they are masked by the high luminous intensity of their stars. However, astronomers led by UNIGE propose detecting molecules present in the exoplanet's atmosphere in ...

45 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (4) May 03, 2018
Neutron stars are fanciful faerie tales of plasma ignoramuses. They were an ad hoc invention to explain other surprises.
https://youtu.be/tiPmoFmBnN8
jonesdave
5 / 5 (4) May 03, 2018
Neutron stars are fanciful faerie tales of plasma ignoramuses. They were an ad hoc invention to explain other surprises.
https://youtu.be/tiPmoFmBnN8


Nope, they are, and have been, pretty much settled science for quite some time. This GW from the merger confirms much of the theory. I doubt that you'll find any scientist in this area to say they don't/ can't exist. Perhaps a bunch of Velikovskian loons, without a relevant qualification between them; but who cares about those nutjobs? They believe that Earth used to orbit Saturn, which immediately disqualifies them from being taken seriously by anybody with an IQ in 3 figures. Which is why they peddle their crap on Youtube and places like this. Can't do real science, bless 'em.
jonesdave
5 / 5 (4) May 03, 2018
I managed to make it about 3 minutes into that idiotic video, before I had to turn it off. I've always known Scott was clueless since I first heard of the loon, and he just confirms it here! The bloke really needs to get an education.
In just that short 3 minutes or so, he suggests that neutron stars were theorised to explain Bell-Burnell's discovery of pulsars in 1967! What an idiot. They were first theorised in the 1930s by Baade & Zwicky, and Chandrasekhar. Then he tries to suggest that every single neutron star must be magically axially aligned with Earth for us to detect the pulses! Talk about thick. The ones we can detect as pulsars are obviously aligned, the rest won't be. Then he makes Benni's mistake of not understanding Pauli's Exclusion Principle, and suggests the neutrons should decay.
Has this guy seriously got a degree? He can't even seem to do research, nor understand some basic physics. Maybe he should stick to rewiring peoples houses, or whatever he does.
granville583762
5 / 5 (2) May 03, 2018
No blackhole, neutron stars are relatively normal.
It does not seem to be confirmed a blackhole as all LIGOs gravity waves detections seem to be. It is actually better staying a combined neutron star or two close orbiting neutron stars, there's more interesting science to be found; for example GW170817 confirmed Sir Isaac Newton's Gravity travelling through the vacuum of space at the speed of light.
Whydening Gyre
5 / 5 (1) May 03, 2018
No blackhole, neutron stars are relatively normal.
It does not seem to be confirmed a blackhole as all LIGOs gravity waves detections seem to be.

How many LIGO wave detections have we had? 3?
And 1 of those was from this very same neutron star...
ALL detections confirmed as blackholes seems a "little" off...
jonesdave
5 / 5 (2) May 03, 2018
No blackhole, neutron stars are relatively normal.
It does not seem to be confirmed a blackhole as all LIGOs gravity waves detections seem to be.

How many LIGO wave detections have we had? 3?


6 confirmed, as far as I can see:
https://en.wikipe...rvations
Whydening Gyre
5 / 5 (1) May 03, 2018
6 confirmed, as far as I can see:
https://en.wikipe...rvations

I'll go with 5 (reference - LVT151012 )
Still, 1 NS merger in 5 observations is FAR from all LIGO detections are blackhole mergings...
jonesdave
5 / 5 (3) May 03, 2018
Regarding Cantthink's Don Scott woo video, here is something ironic; Scott was a Prof. of E.E. at the University of Massachusetts, Amerhurst, back in the day. He obviously had no qualifications in astronomy or astrophysics, and has a very limited grasp of the subject, but is now keen on telling all those people that have, that they are wrong.
Meanwhile, possibly at the same time as Scott was teaching E.E., Russell Hulse and Joseph Taylor were at the same university, and did have relevant physics and astrophysics degrees. In 1974 they discovered PSR B1913+16, the first binary pulsar system discovered. Their work on this system won them the 1993 Nobel Prize in Physics 'for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation."
Shows you what you can achieve when you know what you're doing, rather than spouting bollocks about stuff that you don't understand.

https://en.wikipe...r_binary
jonesdave
5 / 5 (2) May 03, 2018
6 confirmed, as far as I can see:
https://en.wikipe...rvations

I'll go with 5 (reference - LVT151012 )
Still, 1 NS merger in 5 observations is FAR from all LIGO detections are blackhole mergings...


7 if you count LVT151012. I didn't, so 1 in 6 for NS merger detections.
GW150914
GW151226
GW170104
GW170608
GW170814
GW170817 (NS merger)
Whydening Gyre
5 / 5 (2) May 03, 2018
6 confirmed, as far as I can see:
https://en.wikipe...rvations

I'll go with 5 (reference - LVT151012 )
Still, 1 NS merger in 5 observations is FAR from all LIGO detections are blackhole mergings...


7 if you count LVT151012. I didn't, so 1 in 6 for NS merger detections.
GW150914
GW151226
GW170104
GW170608
GW170814
GW170817 (NS merger)

oops...:-) time for new reading glasses?
granville583762
5 / 5 (2) May 03, 2018
oops...:-) time for new reading glasses?

And a Gravitational wave detector, it's difficult if nigh impossible finding blackholes with reading glasses.
Whydening Gyre
5 / 5 (1) May 03, 2018
oops...:-) time for new reading glasses?

And a Gravitational wave detector, it's difficult if nigh impossible finding blackholes with reading glasses.

Sounds like time for Braille method, then...
cantdrive85
1 / 5 (5) May 03, 2018
Neutrons decay in 15 min, into a proton and electron. Neutron stars are unscientific fanciful pontifications of pre-space-age plasma ignoramuses who believed in the "vacuum of space" and other such nonsense. They are abominations of science and reality.
jonesdave
5 / 5 (3) May 03, 2018
Neutrons decay in 15 min, into a proton and electron. Neutron stars are unscientific fanciful pontifications of pre-space-age plasma ignoramuses who believed in the "vacuum of space" and other such nonsense. They are abominations of science and reality.


Oh give it up you ignorant burke. Never heard of the Pauli exclusion principle? Just like the idiot Scott, by the sounds of it. Do an astronomy (in fact any physics) course and you'll learn about it in first year undergrad.
What does the idiot Scott attribute the GWs from the NS merger to? What about the associated EM signatures? What about the (as predicted) r-process nucleosynthesis? Please show us where this know-nothing has written this up, instead of just making a tit of himself on YouTube. Christ, you lot are as pathetic as you are irrelevant. A bunch of scientifically illiterate Velikovskian nobodies.
Whydening Gyre
5 / 5 (3) May 03, 2018
Neutrons decay in 15 min, into a proton and electron. Neutron stars are unscientific fanciful pontifications of pre-space-age plasma ignoramuses who believed in the "vacuum of space" and other such nonsense. They are abominations of science and reality.

One might ask of someone with your boundless expertise, then...
How are neutrons created?
Whydening Gyre
5 / 5 (3) May 03, 2018
Neutrons decay in 15 min, into a proton and electron. Neutron stars are unscientific fanciful pontifications of pre-space-age plasma ignoramuses who believed in the "vacuum of space" and other such nonsense. They are abominations of science and reality.

And...
How many times do you have to be told that a neutron star is not entirely made up of neurons? There exists a large amount of protons and electrons bound tightly together in a very strong gravitational field, which creates interaction, which produces a larger than normal amount of neutrons that are released into space in any given direction.
Neutron stars are called that because of their neutron output, not that they are solely made up of neutrons.
Sheesh...
Da Schneib
5 / 5 (7) May 03, 2018
Here's a nice simple question: if neutrons always decay in 15 minutes, how come there are stable nuclides with neutrons in them?

Just askin'.
granville583762
5 / 5 (3) May 03, 2018
Formation and cooling in neutrons stars
Newly born neutron stars, neutrinos trapped in the opaque stellar core, they diffuse out in seconds, leaving most of their energy heating matter in the core over 500billion K. The next million years, the star cools by emitting neutrinos. Observing neutron star cooling, analyzing the star's x-ray emissions during quiescent periods that followed two periods of x-ray outbursts in 2001 and 2016, showing particularly fast neutrino cooling mechanism, called the direct Urca process occurs early in neutron stars, also in later stages of a few neutron stars. Brown and colleagues obtained direct evidence of a neutron star cooling at a rate consistent with the direct Urca process. From the study of a neutron star a member of the binary MXB 1659-29. MXB 1659-29 undergoing outbursts in 2001 and 2016, providing the chance to observe the cooling of the neutron star during the subsequent quiescent periods. https://physics.a...s/v11/42
Whydening Gyre
5 / 5 (1) May 03, 2018
Here's a nice simple question: if neutrons always decay in 15 minutes, how come there are stable nuclides with neutrons in them?

Just askin'.

That, actually, poses an interesting line of study.
Why don't those extra neutrons decay...?
Maybe our boy, Benni (the nucular engineer) could fill us in...
BTW, did granville correct me correctly by inferring it's the amount of neutrinos emitted vs neutrons?
Thought we couldn't see those...
cantdrive85
1 / 5 (3) May 04, 2018
Nope, they are, and have been, pretty much settled science for quite some time.
LOL, settled science...NS are highly speculative conjecture based on pseudoscientific claptrap. You morons believe in pipe dreams of plasma ignoramuses. Free neutrons decay in 15 minutes, they are unstable proton/electron pairs as such neutrons decay to proton/electron. Your claims that gravity can overcome electrostatic forces is completely baseless, show an actual experiment or in situ observation which supports your pseudoscience.
Neutronium...ROTFLMAO!
Da Schneib
5 / 5 (2) May 04, 2018
@cantthink69 doesn't have an answer for why there are stable nuclides that have neutrons if neutrons always decay in 15 minutes.

How this idiot troll claims to understand neutron stars when it doesn't even understand nuclear physics is a mystery, but only a minor one. One can assume it is lying or insane and move on.
jonesdave
5 / 5 (3) May 04, 2018
LOL, settled science...NS are highly speculative conjecture based on pseudoscientific claptrap.


Wrong, woo boy. In case it escaped your attention, GWs were detected from the merger of two of them. It was seen in EM. It confirmed the speed of gravity as being the speed of light. It confirmed predictions of r-process nucleosynthesis. That was just the latest observation. There are others, all of which confirm theory. There is nothing speculative about it. Unless you want to call the Pauli exclusion principle speculative. In which case you don't accept the periodic table, nor the reason for why chemical reactions happen as they do.
Wouldn't surprise me.
Da Schneib
5 / 5 (3) May 04, 2018
Don't forget the electrons, @jonsey. No one's ever seen an electron. I investigated whether they've ever been observed in a Penning trap, as ions have been. They haven't. No one has ever seen a single electron. Not once. But all of @cantthink69's BS is based on them.

@cantthink69 is a fool, a troll, and an idiot. No evidence will convince it because it ignores evidence. The right way to deal with a troll is put it on ignore and stick to it. Eventually, getting no response, it will die of malnutrition. This is not very satisfying, but it is effective, and it is the only way that will work.
cantdrive85
1 / 5 (3) May 04, 2018
In case it escaped your attention, GWs were detected from the merger of two of them.

Sadly no, your maths pseudoscience doesn't crossover to reality. Just fanciful pontifications of morons such as yourself and da schnied, JA's who believe magnetic fields are actually frozen-in to plasmas and think magnetic monopoles exist. LOL!
jonesdave
5 / 5 (2) May 04, 2018
In case it escaped your attention, GWs were detected from the merger of two of them.

Sadly no, your maths pseudoscience doesn't crossover to reality. Just fanciful pontifications of morons such as yourself and da schnied, JA's who believe magnetic fields are actually frozen-in to plasmas and think magnetic monopoles exist. LOL!


Nothing to do with maths, you idiot. It was an actual detection at 3 separate locations, allowing us to triangulate to a position in the sky. Guess what they saw? A frigging neutron star merger, bozo. With the accompanying predicted EM signatures, and the predicted r-process nucleosynthesis. You really ought to read some actual science, instead of the laughably bad crap peddled by the idiot Thornhill and his moronic acolytes.
cantdrive85
1 / 5 (2) May 04, 2018
And jonesdumb thinks we must be at the center of the Universe as he thinks every pulsar beam is directed at him. LOL!
jonesdave
5 / 5 (2) May 04, 2018
And jonesdumb thinks we must be at the center of the Universe as he thinks every pulsar beam is directed at him. LOL!


Huh? What crap are you on about now? There will be a certain percentage of pulsars whose beams sweep past the Earth. We detect them. There will be a larger percentage that don't. We won't detect them. If that's too complicated for you and the idiot Scott, let me know, and I'll see if I can locate a picture to illustrate it.
Da Schneib
5 / 5 (1) May 04, 2018
Still waiting for coward @cantthink69 to tell us all why, if neutrons all decay after 15 minutes, there appear to be extremely large numbers of atoms with nuclei chock-full of neutrons that last billions of years.

Run away and hide, coward @cantthink69 who has no balls.
cantdrive85
1 / 5 (1) May 05, 2018
There will be a certain percentage of pulsars whose beams sweep past the Earth.

Right, and the Universe orbits around Earth. Is that why it's called "special relativity" jonesdumb? Quantify it jonesdumb, what percentage of these neutronium and strange matter beams will be directed here to the center of the Universe?
jonesdave
5 / 5 (3) May 05, 2018
Right, and the Universe orbits around Earth.


Jesus. See what I mean about thickos? Lol. You do realise that stars will form with random spin axes, yes? They are not all going to be up-down from the galactic disk. Why don't you do some research, for once. The magnetic fields which concentrate the beams are unlikely to be perfectly aligned with the spin axis. So you'll get both magnetic poles throwing out a beam that describes a circle in the sky. How wide is that beam at 1 kpc? Nearer? Further? I'd say there is a decent chance of us detecting quite a few. And we do. QED.
You (and the idiot Scott) are assuming that every frigging pulsar that exists is aimed at Earth! That is just idiocy squared. They are the ones we detect. There will be lots that we don't, because they aren't 'aimed' at Earth. This is grade school stuff, FFS. NSs will form from stars of a certain initial mass range. How many expected to be in the galaxy? How many detected? Go for it.
cantdrive85
1 / 5 (1) May 05, 2018
You (and the idiot Scott) are assuming that every frigging pulsar that exists is aimed at Earth! That is just idiocy squared

You're the one who believes the Earth is the center of it all, the "fingers of god" as pointed out by Arp is another example.
Da Schneib
5 / 5 (2) May 05, 2018
And now the lie switches to false claims about what other posters said.

Sorry, no, @cantthink69, @jones didn't say "the Earth is the center of it all" or anything even remotely like it or interpretable as it. You're lying again, just like you always lie. What's the matter with you, anyway?
alexander2468
5 / 5 (1) May 05, 2018
"It's that smug feeling the brush gets knowing no one is dafter; an insult to the brush if anyone can be dafter"
The Invention of the Neutron Star, its existence depends on being in line of sight

After watching this Infamous Video, one tiny weensy little point stood out, the angle of the pulsars electromagnetic radiation cone, the volume it sweeps through does not have to be stated. Any telescope observing has to be in the volume it sweeps through. It is nothing to do with precise alignment and nobody can make anything from it and you certainly cannot base a theory on being in the area swept through in a given time.

Of course if we only detect neutrons stars through their radiation cone and we can never be inside their radiation cones it could be said neutron stars don't exist but that's not the case, or in the intellect of the proverbial brush "an insult to the brush if anyone can be dafter"
jonesdave
5 / 5 (2) May 05, 2018
You (and the idiot Scott) are assuming that every frigging pulsar that exists is aimed at Earth! That is just idiocy squared

You're the one who believes the Earth is the center of it all, the "fingers of god" as pointed out by Arp is another example.


Nope, idiot. Whoever gave you the idea that 'Earth was at the centre of it.'? Somebody as thick as you, no doubt. Scott, was it? The one who thinks you can accelerate electrons and ions in the same direction, at the same speed, by applying an electric field to them? Or that fusion is happening in the chromosphere, without managing to kill us all with gamma rays? I think we can safely ignore that idiot! Got anyone else?
Do you know what a conic section is, bozo? Does it get larger in diameter as you move away from the apex? Think about it woo boy! I realise this is another area of science in which you are likely clueless, but give it a shot.
jonesdave
5 / 5 (2) May 05, 2018
For the astrophysically challenged, here is a site with a picture of what is happening. I realise EUists like piccies, because words, particularly scientific ones, tend to confuse them:
https://courses.l...n-stars/

Now, wooists, what is happening to the cross-sectional area of the conic section of that beam as it gets further from its progenitor? Come on, you know you can do it! Just a couple more IQ points and you're there! This includes the doofus Scott, if he's reading.
granville583762
5 / 5 (2) May 06, 2018
Angularity and the cone

Unless the beam leaving the neutron star is a parallel beam, its cross sectional area is inversely proportional to its radius. It's not a question of being in its radiation cone at distance or close by, because it is its angle to its centre of rotation, a 20degree cone at right angles the polar axis of rotation gives 160 degrees of not being in the cone, the earth being 79 degrees from the polar axis of rotation gives 158degrees, you will never be in the cone irrespective of distance. Although 1degree out you will never see the pulse no matter how much the pulse spreads out. You can say "are but the star wobbles" the amount the star wobbles is its angle of rotation which is its angularity of the cone. An out of balance mass only appears to wobble; it is actually spinning on centre, its centre of mass!
jonesdave
5 / 5 (2) May 06, 2018
^^^^^^^Nonsense.
granville583762
5 / 5 (1) May 06, 2018
A spherical expanding shell
Angularity and the cone.

There is several explanations, the main one is; does the beam of radiation at a few million miles distance spread out to cover the complete neutron star as a spherical expanding shell, then it does not matter what angle a telescope views the pulsar, the radiation is simply expanding out into the vacuum of space as an expanding shell, where you extract the pulse from the data.
granville583762
5 / 5 (2) May 06, 2018
Somewhere in the path of the beam

There is several explanations, The radiation from pulsars is thought to be primarily emitted from regions near their magnetic poles. If the magnetic poles do not coincide with the rotational axis of the neutron star, the emission beam will sweep the sky, and when seen from a distance, if the observer is somewhere in the path of the beam, it will appear as pulses of radiation coming from a fixed point in space
https://en.wikipe...ron_star
Whydening Gyre
5 / 5 (2) May 06, 2018
There will be a certain percentage of pulsars whose beams sweep past the Earth.

Right, and the Universe orbits around Earth. Is that why it's called "special relativity" jonesdumb? Quantify it jonesdumb, what percentage of these neutronium and strange matter beams will be directed here to the center of the Universe?

He didn't say directed at. He said "sweep past"...
granville583762
5 / 5 (2) May 06, 2018
How a neutron beam stands in the sweepstakes
Extracting the facts from the woo!
This summary of a neutron beam sweeping past earth as it rotates demonstrates there is basically no consensus of what constitutes a beam sweeping through and how it is perceived at a distance, so far still no conclusive definitive explanation of exactly where the neutron beam stand in the sweepstakes

Whydening Gyre
not rated yet May 06, 2018
How a neutron beam stands in the sweepstakes
Extracting the facts from the woo!
This summary of a neutron beam sweeping past earth as it rotates demonstrates there is basically no consensus of what constitutes a beam sweeping through and how it is perceived at a distance, so far still no conclusive definitive explanation of exactly where the neutron beam stand in the sweepstakes


Well, we know for sure, it wouldn't be neutrons. Only the photonic remnant. Hi energy, from my understanding (x-rays, gamma rays)...
granville583762
5 / 5 (1) May 07, 2018
The question was the sweepstakes
How a neutron beam stands in the sweepstakes This summary of a neutron beam sweeping past earth as it rotates demonstrates there is basically no consensus of what constitutes a beam sweeping through and how it is perceived at a distance, so far still no conclusive definitive explanation of exactly where the neutron beam stand in the sweepstakes

The constituents of the neutron beam was not the question; It is how the relative position of the telescope on earth is when observing the pulses from the neutron star is still up in the air with no definitive explanation.
granville583762
5 / 5 (2) May 07, 2018
The existence of neutron stars lies in their distinctive detection

"The discovery of pulsars by Jocelyn Bell Burnell in 1967 was the first observational suggestion that neutron stars exist.
The radiation from pulsars is thought to be primarily emitted from regions near their magnetic poles. If the magnetic poles do not coincide with the rotational axis of the neutron star, the emission beam will sweep the sky, and when seen from a distance, if the observer is somewhere in the path of the beam https://en.wikipe...ron_star "

Their discovery seems to be related to their distinctive pulses identifying them as pulsar neutron stars inside an expanding nebula as this is the question? As each article concerning pulses states "the observer is somewhere in the path of the beam". It is consistently quoted.
granville583762
5 / 5 (1) May 10, 2018
granville583762> Angularity and the cone

Unless the beam leaving the neutron star is a parallel beam, its cross sectional area is inversely proportional to its radius. It's not a question of being in its radiation cone at distance or close by, because it is its angle to its centre of rotation, a 20degree cone at right angles the polar axis of rotation gives 160 degrees of not being in the cone, the earth being 79 degrees from the polar axis of rotation gives 158degrees, you will never be in the cone irrespective of distance. Although 1degree out you will never see the pulse no matter how much the pulse spreads out. You can say "are but the star wobbles" the amount the star wobbles is its angle of rotation which is its angularity of the cone. An out of balance mass only appears to wobble; it is actually spinning on centre, its centre of mass!

jonesdave> ^^^^^^^Nonsense.

Why is "the observer is somewhere in the path of the beam" Nonsense?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.