Researchers see beam of light from first confirmed neutron star merger emerge from behind sun

July 2, 2018, University of Warwick
Artist's impression of jets of material from first confirmed neutron star merger. Credit: Mark Garlick/University of Warwick

A research team led by astronomers at the University of Warwick had to wait over 100 days for the sight of the first of confirmed neutron star merger to remerge from behind the glare of the sun.

They were rewarded with the first confirmed visual sighting of a jet of material that was still streaming out from merged star exactly 110 days after that initial cataclysmic event was first observed. Their observations confirm a key prediction about the aftermath of neutron star mergers.

The binary neutron star merger GW170817 occurred 130 million years away in a galaxy named NGC 4993. It was detected in August 2017 by the Advanced Laser Interferometer Gravitational-Wave Observatory (Adv-LIGO), and by Gamma Ray Burst (GRB) observations, and then became the first ever neutron star merger to be observed and confirmed by visual astronomy.

After a few weeks the merged star then passed behind the glare of our sun leaving it effectively hidden from astronomers until it remerged from that glare 100 days after the merger event. It was at that point that the University of Warwick research team were able to use the Hubble Space Telescope to see the star was still generating a powerful beam of light in a direction that, while off centre to the Earth, was starting to spread out in our direction.

Their research has just been published in a paper entitled: "The optical afterglow of the short associated with GW170817" in Nature Astronomy's website at 4pm UK time on Monday 02 July 2018.

The lead author of the paper, Dr. Joe Lyman from the University of Warwick's Department of Physics, said:

"Early on, we saw visible light powered by radioactive decay of heavy elements, over a hundred days later and this has gone, but now we see a jet of material, ejected at an angle to us, but at almost of the speed of light. This is quite different than some people have suggested, that the material wouldn't come out in a jet, but in all directions."

Professor Andrew Levan from the University of Warwick's Department of Physics, another of the papers leading authors added:

"If we'd looked straight down this beam we'd have seen a really powerful burst of gamma-ray. This means that it is quite likely that every neutron star that mergers actually creates a , but we only see a small fraction of them because the jet doesn't line up all that often. Gravitational waves are a whole new way to find this kind of event, and they might be more common than we think."

These observations confirm the prediction made by the second author of the paper, Dr. Gavin Lamb from the University of Leicester's Department of Physics and Astronomy, said that these types of events will reveal the structure of these jets of material travelling close to the speed of light:

"The behaviour of the light from these jets, how it brightens and fades, can be used to determine the velocity of the material throughout the jet. As the afterglow brightens we are seeing deeper into the jet structure and probing the fastest components. This will help us understand how these jets of material, travelling close to the speed of light, are formed and how they are accelerated to these phenomenal velocities."

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

More information: The optical afterglow of the short gamma-ray burst associated with GW170817 , Nature Astronomy (2018). DOI: 10.1038/s41550-018-0511-3 , https://www.nature.com/articles/s41550-018-0511-3

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Surveillance_Egg_Unit
4.2 / 5 (5) Jul 02, 2018
"It was at that point that the University of Warwick research team were able to use the Hubble Space Telescope to see the star was still generating a powerful beam of light in a direction that, while off centre to the Earth, was starting to spread out in our direction."

I suppose that, depending on the intensity of the beam, and other factors such as speed and line of sight, it may be prudent for humanity to prepare massive underground bunkers/structures to save at least SOME humans, animals and plant life from the possibility of mass dying due to the Earth being fully hit with GRBs head-on. However, due to the vast distance between Earth and the newly-merged Neutron star, the GRB may be less lethal.
-CONTINUED-
Surveillance_Egg_Unit
3.7 / 5 (3) Jul 02, 2018
-CONTINUED-
Perhaps such a direct hit of the Earth by GRBs has happened at some time in Earth's past. Such an event may have even caused a die-out of some life forms.

" It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction."
Anonym262722
2.3 / 5 (3) Jul 02, 2018
'Signals from a spectacular neutron star merger that made gravitational waves are slowly fading away'.

I have three questions about this sentence: 1) Was it neutron star merger, 2) Did it make gravitational Waves and 3) Did the initially observed afterglow of INCEASING EM radiation intensity come from the source of GRB - or from some occlusion (like in BICEP2) dimming the incoming GRB radiation during any time period of the 130 M year travel from source to receiver, such as CME or other local event in the direction toward the SUN?
torbjorn_b_g_larsson
4.3 / 5 (6) Jul 03, 2018
@SEU: Yeah, no.

In 4 billion years of evolution, there is one or two mass extinctions that are possibly tied to GRBs. And mammal species becomes 1-2 million years before replaced by speciation, so there is at most a 1/2000 risk. Meanwhile, Musk plans to bore habitats on Mars while we live in a 6th large mass extinction that we ourselves caused, the former a solution for free and the latter an acute problem to solve.

@Anonym: Yes on all three; the observation of an oblique, weak jet suggests that the initial neutrino and x-ray burst hit a previously ejected gas shell that caused the initial glow as it reacted - including with radioactive causing nucleosynthesis (primarily due to neutrinos, I think) - to the radiation.
Surveillance_Egg_Unit
4 / 5 (3) Jul 03, 2018
@t b g larsson
Thank you for your reply to my concerns.
The timeline of the Earth's existence is not the issue. I did not specify any particular species or era/epoch such as the Mesozoic, e.g. that may have been wiped out due to a direct hit by an asteroid. But I did specifically say "Life Forms" which is all-encompassing regardless of era. Speciation and evolution are evidence that Life Forms adapt and prevail. Without more scientific evidence it is impossible to recount all the possibilities of GRB direct hit or its frequency anywhere on the Earth resulting in a die-out of Life Forms. As our Milky Way draws closer to Andromeda there may be more incidences of mergers of binaries resulting in GRBs from a Neutron star directed at the Earth...although it IS a long way off.

But the future and safety of humankind may depend on avoiding all risks of interstellar issues that result in chaotic conditions on our home planet.

Elon Musk demonstrates wisdom and elan. I like that.

Anonym262722
2 / 5 (4) Jul 04, 2018
1)There are many known and assumed sources for GRB other than the first ever assumed NS merge event, including magnetic and ionos-sphere disturbances originating from Sun. 2) There are no visually confirmed GW events with other GR based foundations than 'Einstein said so' or Suntola DU predicting the present deceleration rate of expansion as - 10^-21/ms. This required aLIGO side-band circulation by the averaging leap of 75-284 to just eliminate the uniform background strain -becoming a victim to local directional disturbances such as mass waves of solar wind and CME variations. 3) The triangulated arrival direction of GW has to be far away from the Sun disturbances - and perpendicular to the 2-D vacuum tube planes of ALL receiver stations (which is impossible). So, you have to perform relative orientations in triangulation to remove the serially correlated bias in the fashion of D.C. Brown range network adjustment in 1960's - this may need building 3rd vacuum tube at each station...
jonesdave
3 / 5 (8) Jul 04, 2018
^^^^^Sounds like nonsense to me. The signal was detected at two different sites in the U.S., and a third in Italy. Three = triangulation! Yes, it was a gravitational wave - what else would it be? Yes, it was a NS merger - what else would it be? There were very good theoretical predictions of what such a signal should look like, both as a GW and in the EM for a NS merger. Guess what? Everything we saw pretty much matches those predictions. And the GRB was not the only reason for assigning this to a NS merger. Read the papers. Look up r-process nucleosynthesis. Do this before commenting again.
Anonym262722
2.3 / 5 (3) Jul 04, 2018
@jonesdave
I understand your thinking as similar controversies took place in my field of surveying sciences some 40-50 years ago due to some profound math foundations of estimation theory that were not understood 400-500 years ago to explain the epicycle based bias. Einstein's GR and quantum theories did not remove this problem in physics foundations resulting in today's epicycles of Dark Energy/Matter to explain 1998 SN1a data in cosmic scale where GR starts failing, by e.g. predicting accelerating (vs. correct decelerating) expansion rate. This together with other 5-10 blunders revealed by Suntola DU would make it impossible to resolve GW at any circulation rate of aLIGO side-band data. DU Mach and entanglement principles of photogrammetric space telescope and 'cosmic GPS' triangulations of 4/5-D cosmic object locations may cure these problems in future LIGO/LISA designs - but needs open minds of astrophysicists. Anyone can make mistakes like Nobel committees....but not ME nor YOU!
savvys84
4 / 5 (1) Jul 10, 2018
Bravo a rare event captured
savvys84
3 / 5 (2) Jul 10, 2018
^^^^^Sounds like nonsense to me. The signal was detected at two different sites in the U.S., and a third in Italy. Three = triangulation! Yes, it was a gravitational wave - what else would it be? Yes, it was a NS merger - what else would it be? There were very good theoretical predictions of what such a signal should look like, both as a GW and in the EM for a NS merger. Guess what? Everything we saw pretty much matches those predictions. And the GRB was not the only reason for assigning this to a NS merger. Read the papers. Look up r-process nucleosynthesis. Do this before commenting again.

The signal was only detected at LIGO in the us, who in turn alerted the other 2 sites, where to look. So how was the triangulation done?
jonesdave
2.7 / 5 (7) Jul 10, 2018
^^^^^Sounds like nonsense to me. The signal was detected at two different sites in the U.S., and a third in Italy. Three = triangulation! Yes, it was a gravitational wave - what else would it be? Yes, it was a NS merger - what else would it be? There were very good theoretical predictions of what such a signal should look like, both as a GW and in the EM for a NS merger. Guess what? Everything we saw pretty much matches those predictions. And the GRB was not the only reason for assigning this to a NS merger. Read the papers. Look up r-process nucleosynthesis. Do this before commenting again.

The signal was only detected at LIGO in the us, who in turn alerted the other 2 sites, where to look. So how was the triangulation done?


Like I said, read the papers:
http://iopscience...20c/meta
jonesdave
1.8 / 5 (5) Jul 10, 2018
The signal was only detected at LIGO in the us, who in turn alerted the other 2 sites, where to look. So how was the triangulation done?


How can a gravitational wave detection tell other GW observatories "where to look"? It was detected at both US sites, and in Italy. If the papers are too confusing, try the press release:
https://www.ligo....gw170817

Though the LIGO detectors first picked up the gravitational wave in the United States, Virgo, in Italy, played a key role in the story. Due to its orientation with respect to the source at the time of detection, Virgo recovered a small signal; combined with the signal sizes and timing in the LIGO detectors, this allowed scientists to precisely triangulate the position in the sky. After performing a thorough vetting to make sure the signals were not an artifact of instrumentation, scientists concluded that a gravitational wave came from a relatively small patch in the southern sky.


Anonym262722
3 / 5 (2) Jul 10, 2018
The direction of the small patch was too close to Sun to rule out Sun as the source of GW disturbance. The first assumed BH merger caused GW was also associated with GRB event but it was ruled out as a mistake by LIGO. Did someone else see early reports of NS merger GW event where the alert was given by the GRB observation before the GW detection was confirmed by all stations - the GRB arrival time is more unique (unbiasedly estimable) than correlated GW arrival time differences among 3 stations. LIGO matching technique with assumed reference shape of strain needs good initial values in nonlinear estimation process with or without the calibration lines.
granville583762
5 / 5 (5) Aug 02, 2018
Telescopes in solar orbit prevents line of site obstruction
phys.org> After a few weeks the merged star then passed behind the glare of our sun leaving it effectively hidden from astronomers until it remerged from that glare 100 days after the merger event. It was at that point that the University of Warwick research team were able to use the Hubble Space Telescope to see the star was still generating a powerful beam of light in a direction that, while off centre to the Earth, was starting to spread out in our direction

A simple solution of putting multiple telescopes in solar orbit bypasses the sun blocking our view transmitting data from telescope to telescope to earth, with talk of terra forming a lifeless airless barren waste land of mars to the detriment of earth, solar orbital telescopes is a cheap constructive project
savvys84
3 / 5 (2) Aug 03, 2018
So what in the LIGO instrumentation acts like an aircrafts ADF , and how does it work? Anyone?
ADF stands for automatic direction finder

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