Years after we detected two neutron stars crashing into each other, we're still picking up X-rays. We don't know why
(2020/10/14)
- Reference: 1602658449
- News link: https://www.theregister.co.uk/2020/10/14/binary_star_xray/
- Source link:
After a thousand days of observations, the continuing X-ray radiation from two neutron stars smashing into one another has left astronomers puzzled.
The collision, code-named [1]GW170817 , was picked up by our planet's LIGO and Virgo gravitational wave detectors in mid-2017. The incredible crash, some 130 million light-years away, spilled a heady mix of electromagnetic signals into space as well as the gravitational wave we detected here on Earth.
One remarkable feature of the merger was its kilonova, which immediately followed an initial gamma-ray burst. Light from this kilonova faded about three weeks after GW170817 was observed, as expected. Curiously, though, X-rays were picked up nine days after the merger's gravitational wave was detected, and they continue to linger well past what’s typically considered normal. The X-ray afterglow is still visible three years after the detection of GW170817.
“The X-rays persist for much longer, and we do not understand why,” Eleonora Troja, an associate research scientist at the University of Maryland in the US, who helped detect GW170817, told The Register .
It's thought the X-rays are the result of a physical process, related to the neutron star merger, not yet observed or considered by scientists, or that the kilonova created its own shock wave through space that resulted in the delayed X-ray emissions.
“It may be that our models are somehow incomplete and do not fully capture the complexity of these extreme phenomena, or we may be seeing something else," Troja said. "Maybe it’s the remnant of the kilonova explosion, or signs from the stellar object that survived the gravitational wave merger.”
Massive news, literally: Three super-boffins awarded Nobel Prize in physics for their black-hole breakthroughs [2]READ MORE
Indeed, a paper, of which Troja is lead author, was [3]published in the Monthly Notices of the Royal Astronomical Society on Monday, and suggests the neutron star collision created another neutron star that’s been emitting x-rays for all these years.
“This third possibility is intriguing, because it will place an important constraint on the poorly known equation of state of nuclear matter,” [4]added Bing Zhang, a co-author of the paper and an astrophysics professor at the Uni of Maryland.
The X-rays are incredibly energetic and bright: Troja said the emissions are 100 billion times brighter than those from the Sun, judging from the latest readings.
“We think that the jet has traveled for over 10,000 billion kilometres, that is larger than the size of our Solar System,” she told us. "If this jet was launched by our Sun, it would be way further than Pluto, making its way through the Oort cloud.
“In the same way we see the remnants of supernova explosions, like the Crab Nebula or the Jellyfish nebula, we may discover the remnant of a kilonova explosion. We have never seen such a thing before, it only exists in our theories and models. This could really change the way we search for gravitational wave mergers, and the idea of discovering a new type of celestial source is very exciting." ®
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[1] https://www.theregister.com/2018/09/05/neutron_star_merger_faster_than_light/
[2] https://www.theregister.com/2020/10/07/nobel_prize_physics/
[3] https://academic.oup.com/mnras/article/498/4/5643/5918334
[4] https://www.unlv.edu/news/release/astronomers-find-x-rays-lingering-years-after-neutron-star-collision
[5] https://whitepapers.theregister.com/
The collision, code-named [1]GW170817 , was picked up by our planet's LIGO and Virgo gravitational wave detectors in mid-2017. The incredible crash, some 130 million light-years away, spilled a heady mix of electromagnetic signals into space as well as the gravitational wave we detected here on Earth.
One remarkable feature of the merger was its kilonova, which immediately followed an initial gamma-ray burst. Light from this kilonova faded about three weeks after GW170817 was observed, as expected. Curiously, though, X-rays were picked up nine days after the merger's gravitational wave was detected, and they continue to linger well past what’s typically considered normal. The X-ray afterglow is still visible three years after the detection of GW170817.
“The X-rays persist for much longer, and we do not understand why,” Eleonora Troja, an associate research scientist at the University of Maryland in the US, who helped detect GW170817, told The Register .
It's thought the X-rays are the result of a physical process, related to the neutron star merger, not yet observed or considered by scientists, or that the kilonova created its own shock wave through space that resulted in the delayed X-ray emissions.
“It may be that our models are somehow incomplete and do not fully capture the complexity of these extreme phenomena, or we may be seeing something else," Troja said. "Maybe it’s the remnant of the kilonova explosion, or signs from the stellar object that survived the gravitational wave merger.”
Massive news, literally: Three super-boffins awarded Nobel Prize in physics for their black-hole breakthroughs [2]READ MORE
Indeed, a paper, of which Troja is lead author, was [3]published in the Monthly Notices of the Royal Astronomical Society on Monday, and suggests the neutron star collision created another neutron star that’s been emitting x-rays for all these years.
“This third possibility is intriguing, because it will place an important constraint on the poorly known equation of state of nuclear matter,” [4]added Bing Zhang, a co-author of the paper and an astrophysics professor at the Uni of Maryland.
The X-rays are incredibly energetic and bright: Troja said the emissions are 100 billion times brighter than those from the Sun, judging from the latest readings.
“We think that the jet has traveled for over 10,000 billion kilometres, that is larger than the size of our Solar System,” she told us. "If this jet was launched by our Sun, it would be way further than Pluto, making its way through the Oort cloud.
“In the same way we see the remnants of supernova explosions, like the Crab Nebula or the Jellyfish nebula, we may discover the remnant of a kilonova explosion. We have never seen such a thing before, it only exists in our theories and models. This could really change the way we search for gravitational wave mergers, and the idea of discovering a new type of celestial source is very exciting." ®
Get our [5]Tech Resources
[1] https://www.theregister.com/2018/09/05/neutron_star_merger_faster_than_light/
[2] https://www.theregister.com/2020/10/07/nobel_prize_physics/
[3] https://academic.oup.com/mnras/article/498/4/5643/5918334
[4] https://www.unlv.edu/news/release/astronomers-find-x-rays-lingering-years-after-neutron-star-collision
[5] https://whitepapers.theregister.com/
We know we don't know
Version 1.0
This is a good illustration of the history of knowledge - go ask politicians or your average Joe and they will tell you that we know everything about the universe. But if you ask scientists they will tell you that there are some interesting observations and theories about the universe that suggest we have some good ideas about what might be out there.
400 years ago an apple (fruit not a phone) fell on Issac Newton's head and started a new view of the universe leading to a lot of new knowledge, so I think that we can assume that our current view might change in the next 400 years ... perhaps the kids in school will be laughing about a discovery back in 2024 when a scientist dropped his phone and suddenly thought that the light speed limit only applied to the visible universe?
Its obvious
John Jennings
Its a navigational beacon to warn intergalactic motorists of the collision.
Someone forgot to lift the cones (again!)
"the emissions are 100 billion times brighter than those from the Sun"
So they're getting x-rays from a merger that are stupendously bright. Did they point an optical telescope there to see if anything was visible ?
How about infra-red ? If the two neutron stars don't have nuclear fusion, they should certainly be radiating heat like crazy.
Of course, if they've become a black hole, then the source has to come from the jet, but couldn't the jet be visible if it 10,000 billion kilometers long ?
EDIT : after a short search, I found [1]this article that details nicely all the important things about this merger, and there are many. But nothing on the jet.
[1] https://en.wikipedia.org/wiki/GW170817