from the if-only-we-could-make-the-general-public-grow-brighter dept.
Neutron-star merger yields new puzzle for astrophysicists
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 light years away and sent gravitational waves rippling through the universe.
New observations from NASA's orbiting Chandra X-ray Observatory, reported in Astrophysical Journal Letters, indicate that the gamma ray burst unleashed by the collision is more complex than scientists initially imagined.
"Usually when we see a short gamma-ray burst, the jet emission generated gets bright for a short time as it smashes into the surrounding medium – then fades as the system stops injecting energy into the outflow," says McGill University astrophysicist Daryl Haggard, whose research group led the new study. "This one is different; it's definitely not a simple, plain-Jane narrow jet."
Brightening X-Ray Emission from GW170817/GRB 170817A: Further Evidence for an Outflow (open, DOI: 10.3847/2041-8213/aaa4f3) (DX)
Previously: LIGO May Have Detected Merging Neutron Stars for the First Time
"Kilonova" Observed Using Gravitational Waves, Sparking Era of "Multimessenger Astrophysics"
Related Stories
LIGO, the Laser Interferometer Gravitational-wave Observatory made physics history by managing to detect the previously elusive gravitational waves predicted by Einstein's Theory of General Relativity for the first time. They have, since they began operation, thrice observed the gravitational wave signatures emitted by the mergers of what are believed to be massive binary black hole systems. However, there is no confirmation of these events beyond the gravitational wave detection since black hole mergers may not emit anything else besides the gravitational waves. However, the merger of two neutron stars such as what is predicted to eventually happen to the Hulse–Taylor binary (which provided the first indirect confirmation of gravitational waves in the 1970s) will not only produce copious gravitational waves but possibly also a gamma ray burst or some other associated emission of electromagnetic radiation. The gravitational waves emitted by such an event would be weaker and harder for LIGO to detect, but on August 18th, noted astrophysicist J. Craig Wheeler tweeted a tantalising hint that they might actually have seen just such a thing happen:
New LIGO. Source with optical counterpart. Blow your sox off!
New Scientist reports that LIGO spokesperson David Shoemaker has not denied the rumour, and it seemed that four days after Wheeler's tweet the Hubble Space Telescope had been observing a neutron star binary candidate in the galaxy NGC 4993, which has since been deleted. From the article:
LIGO spokesperson David Shoemaker dodged confirming or denying the rumours, saying only "A very exciting O2 Observing run is drawing to a close August 25. We look forward to posting a top-level update at that time."
Speculation is focused on NGC 4993, a galaxy about 130 million light years away in the Hydra constellation. Within it, a pair of neutron stars are entwined in a deadly dance. While astronomers are staying silent on whether they are engaged in optical follow-ups to a potential gravitational wave detection, last night the Hubble Space Telescope turned its focus to a binary neutron star merger within the galaxy. A publicly available image of this merger was later deleted.
Further coverage and commentary from astrophysicist Ethan Siegel at Starts With A Bang.
Scientists Witness Huge Cosmic Crash, Find Origins of Gold
It started in a galaxy called NGC 4993, seen from Earth in the Hydra constellation. Two neutron stars, collapsed cores of stars so dense that a teaspoon of their matter would weigh 1 billion tons, danced ever faster and closer together until they collided, said Carnegie Institution astronomer Maria Drout.
The crash, called a kilonova, generated a fierce burst of gamma rays and a gravitational wave, a faint ripple in the fabric of space and time, first theorized by Albert Einstein.
The signal arrived on Earth on Aug. 17 after traveling 130 million light-years. [...] The colliding stars spewed bright blue, super-hot debris that was dense and unstable. Some of it coalesced into heavy elements, like gold, platinum and uranium. Scientists had suspected neutron star collisions had enough power to create heavier elements, but weren't certain until they witnessed it. "We see the gold being formed," said Syracuse's Brown.
So the ring on your finger is actually the skeletal remains of neutron stars.
Observatories Across the World Announce Groundbreaking New Gravitational Wave Discovery
Today, physicists and astronomers around the world are announcing a whole new kind of gravitational wave signal at a National Science Foundation press conference in Washington, DC. But it's not just gravitational waves. That August day, x-ray telescopes, visible light, radio telescopes, and gamma-ray telescopes all spotted a flash, one consistent with a pair of neutron stars swirling together, colliding and coalescing into a black hole. The observation, called a "kilonova," simultaneously answered questions like "where did the heavy metal in our Universe come from" and "what causes some of the gamma-ray bursts scientists have observed since the 60s." It also posed new ones.
[...] All in all, the discovery marks an important milestone in gravitational wave astronomy and proof that LIGO and Virgo do more than spot colliding black holes. At present, the detectors are all receiving sensitivity upgrades. When they come back online, they may see other sources like some supernovae or maybe even a chorus of background gravitational waves from the most distant stellar collisions.
https://gizmodo.com/observatories-across-the-world-announce-groundbreaking-1819500578
[Also Covered By]:
- ESOcast 133: ESO Telescopes Observe First Light from Gravitational Wave Source
- In a First, Gravitational Waves Linked to Neutron Star Crash
- New gravitational wave discovery confirms dawn of a new field of astronomy
- What Have Gravitational-Wave Detectors Discovered?
- Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy (archive)
Papers:
Optical emission from a kilonova following a gravitational-wave-detected neutron-star merger (open, DOI: 10.1038/nature24291) (DX)
Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger (open, DOI: 10.1038/nature24298) (DX)
A gravitational-wave standard siren measurement of the Hubble constant (open, DOI: 10.1038/nature24471) (DX)
The X-ray counterpart to the gravitational-wave event GW170817 (open, DOI: 10.1038/nature24290) (DX)
A kilonova as the electromagnetic counterpart to a gravitational-wave source (open, DOI: 10.1038/nature24303) (DX)
Origin of the heavy elements in binary neutron-star mergers from a gravitational-wave event (open, DOI: 10.1038/nature24453) (DX)
Multi-messenger Observations of a Binary Neutron Star Merger (open, DOI: 10.3847/2041-8213/aa91c9) (DX)
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A (open, DOI: 10.3847/2041-8213/aa920c) (DX)
An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A (open, DOI: 10.3847/2041-8213/aa8f41) (DX)
INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational-wave Event GW170817 (open, DOI: 10.3847/2041-8213/aa8f94) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera (open, DOI: 10.3847/2041-8213/aa9059) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models (open, DOI: 10.3847/2041-8213/aa8fc7) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. III. Optical and UV Spectra of a Blue Kilonova from Fast Polar Ejecta (open, DOI: 10.3847/2041-8213/aa9029) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. IV. Detection of Near-infrared Signatures of r-process Nucleosynthesis with Gemini-South (open, DOI: 10.3847/2041-8213/aa905c) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. V. Rising X-Ray Emission from an Off-axis Jet (open, DOI: 10.3847/2041-8213/aa9057) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta (open, DOI: 10.3847/2041-8213/aa905d) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale (open, DOI: 10.3847/2041-8213/aa9055) (DX)
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VIII. A Comparison to Cosmological Short-duration Gamma-Ray Bursts (open, DOI: 10.3847/2041-8213/aa9018) (DX)
The Discovery of the Electromagnetic Counterpart of GW170817: Kilonova AT 2017gfo/DLT17ck (open, DOI: 10.3847/2041-8213/aa8edf) (DX)
A Deep Chandra X-Ray Study of Neutron Star Coalescence GW170817 (open, DOI: 10.3847/2041-8213/aa8ede) (DX)
The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source (open, DOI: 10.3847/2041-8213/aa905e) (DX)
The Emergence of a Lanthanide-rich Kilonova Following the Merger of Two Neutron Stars (open, DOI: 10.3847/2041-8213/aa90b6) (DX)
Observations of the First Electromagnetic Counterpart to a Gravitational-wave Source by the TOROS Collaboration (open, DOI: 10.3847/2041-8213/aa9060) (DX)
The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source (open, DOI: 10.3847/2041-8213/aa9116) (DX)
The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817 (open, DOI: 10.3847/2041-8213/aa9110) (DX)
The Rapid Reddening and Featureless Optical Spectra of the Optical Counterpart of GW170817, AT 2017gfo, during the First Four Days (open, DOI: 10.3847/2041-8213/aa9111) (DX)
Optical Follow-up of Gravitational-wave Events with Las Cumbres Observatory (open, DOI: 10.3847/2041-8213/aa910f) (DX)
A Neutron Star Binary Merger Model for GW170817/GRB 170817A/SSS17a (open, DOI: 10.3847/2041-8213/aa91b3) (DX)
Previously: European Southern Observatory to Announce "Unprecedented Discovery" on Monday
Original Submission #1 Original Submission #2 Original Submission #3
Okay, Last Year's Kilonova Did Probably Create a Black Hole
In August of 2017 [open, DOI: 10.1103/PhysRevLett.119.161101] [DX], another major breakthrough occurred when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected waves that were believed to be caused by a neutron star merger. Shortly thereafter, scientists at LIGO, Advanced Virgo, and the Fermi Gamma-ray Space Telescope were able to determine where in the sky this event (known as a kilonova) occurred.
This source, known as GW170817/GRB, has been the target of many follow-up surveys since it was believed that the merge could have led to the formation of a black hole. According to a new study by a team that analyzed data from NASA's Chandra X-ray Observatory since the event, scientists can now say with greater confidence that the merger created a new black hole in our galaxy.
[...] While the LIGO data provided astronomers with a good estimate of the resulting object's mass after the neutron stars merged (2.7 Solar Masses), this was not enough to determine what it had become. Essentially, this amount of mass meant that it was either the most massive neutron star ever found or the lowest-mass black hole ever found (the previous record holders being four or five Solar Masses).
Previously: "Kilonova" Observed Using Gravitational Waves, Sparking Era of "Multimessenger Astrophysics"
Neutron-Star Merger Grows Brighter
(Score: 1, Informative) by Anonymous Coward on Tuesday January 23 2018, @03:54AM
Puzzle? Well, what are you waiting for?
You have a story lead! Go there, see what's going on, come back and report
(Score: 3, Informative) by Gaaark on Tuesday January 23 2018, @11:17AM
from the if-only-we-could-make-the-general-public-grow-brighter dept.
Science
takyon writes:
Neutron-star merger yields new puzzle for astrophysicists Neutron-star merger yields new puzzle for astrophysicists
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2, Funny) by Anonymous Coward on Tuesday January 23 2018, @12:38PM (2 children)
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(Score: 0) by Anonymous Coward on Wednesday January 24 2018, @04:17PM
REPETITA JUVANT
(i.e. repetita juvant)
(Score: 2) by Bot on Wednesday January 24 2018, @04:21PM
Or, possibly, his "Neutron-star merger yields new puzzle for astrophysicists" key is a bit stuck.
Account abandoned.