Gravitational waves indicate that a neutron star feeds on a black hole. The LIGO and Virgo observatories have seen ripples since the first detection of this long-awaited event. Gravitational waves indicate that a neutron star feeds on a black hole. An artist’s presentation of a star ejecting a bright stream of debris when interrupted by a supermassive black hole. Image Credit: NASA and JPL
Gravitational waves indicate
Gravitational waves may have given the first sighting of a black hole devouring a neutron star. If confirmed, it would be the first evidence of the existence of such a binary system. The news comes just a day after astronomers detected gravitational waves from the merging of two neutron stars for the second time.
On April 26 at 15:22:17 UTC, the twin detectors of the Laser Interferometer Gravitational Wave Observatory (LIGO) in the United States and the Virgo Observatory in Italy reported bursts of an unusual wave type. Astronomers are still analyzing the data and doing computer simulations to interpret it.
But they are already considering the tantalizing possibility of having discovered a long-awaited discovery that could yield a wealth of cosmic information, from accurate tests of the general theory of relativity to measuring the expansion rate of the universe. Astronomers around the world are also rushing to observe the phenomenon using different types of telescopes.
“I think the classification leans toward a neutron star-black hole merger,” says Chad Hanna, a senior member of LIGO’s data analysis team and a physicist at Pennsylvania State University in University Park. But the signal was not very strong, which means it could be a fluke.
“I think people should be excited about this, but they should also know that the importance is much less” than many previous events, he says. LIGO and Virgo had previously captured gravitational waves, weak waves in the fabric of space-time, from two types of cataclysmic events: the merger of two black holes and those of two neutron stars. The latter are small but ultra-dense objects that form after the collapse of stars more massive than the Sun.
The latest event, tentatively labeled # S190426c, appears to have occurred about 375 megaparsecs (1.2 billion light years) away, the LIGO-Virgo team calculated. Researchers have created a map of the sky that shows where gravitational waves are most likely to originate and have sent this information as a public alert, for astronomers around the world to search the sky for the light of the event.
Combining gravitational waves
Combining gravitational waves with other forms of radiation in this way can reveal more information about the phenomenon than any type of data. Manasi Kasliwal, an astrophysicist at the California Institute of Technology in Pasadena, leads one of several projects designed to do this kind of follow-up work, called Global Relay of Observatories Watching Transients Happen (GROWTH).
Her team could command a world robotic telescope. In this case, the researchers immediately introduced one to India, where it was night when the gravitational waves arrived. “Weather permitting, I think in less than 24 hours we should have coverage of almost the entire sky on the map,” she says.
That event was a clear case of two neutron stars merging, Hanna says, about two years after the first historical discovery of such an event in August 2017. Researchers can generally make such a call because the waves reveal the masses of objects. involved; Objects twice as heavy as the Sun are expected to be neutron stars.
Volume of the waves
Based on the volume of the waves, the researchers also estimated that the collision occurred about 150 megaparsecs (500 million light years) away, Hannah says. This was almost three times more than the 2017 merger.
Iair Arcavi, a Tel Aviv University astrophysicist working at Las Cumbres Observatory, one of GROWTH’s competitors, was in Baltimore, Maryland, to attend a conference called Enabling Multi-Messenger Astrophysics (EMMA). It is – the practice of seeing these events in many. Wavelength.. the alert for the April 25 incident came at 5:01 am. “I set it up to send a text message and it woke me up,” he says.
A storm of activity swept through the gathering, with astronomers typically exchanging information with each other as they sat with their laptops around the coffee table. Astronomer Andy Howell tweeted: “We’re losing our minds here at # EMMA2019.”
But in this case, unlike many others, LIGO and Virgo could not point to the direction in the sky where the waves were coming from. All the researchers could tell was that the signal was coming from a wide area that covers about a quarter of the sky. He reduced the area a day later.
Still, astronomers had highly respected machines to make these kinds of discoveries, and the data they collected the following night should eventually reveal the source, Kasliwal says. “If it had been present in that area, there is no way we would have missed it.”
In the 2017 neutron star merger, the combination of observations at different wavelengths produced an enormous amount of science. Two seconds after the event, an orbiting telescope had detected bursts of gamma rays, possibly released when the merged star collapsed into a black hole.
And 70 other observatories had been busy for months, watching the event unfold across the electromagnetic spectrum, from radio waves to X-rays. If the April 26 event isn’t a neutron star-black hole merger, it’s probably a neutron star collision as well, bringing this type of total detection to three.
But observing a black hole like a neutron star can provide a wealth of information that no other type of event can provide, says B.S., a theoretical physicist at LIGO in the state of Pennsylvania. Satyaprakash says. To begin with, he confirms that these highly sought-after systems exist, originating from binary stars of vastly different masses.
The LIGO-Virgo collaboration
The orbits the two objects detect in the final stages of their approach may be different from the orbits seen with pairs of black holes. In the case of a neutron star black hole, the most massive black hole will gobble up the space around it as it spins. “The neutron star will rotate in a circular orbit rather than a semicircular orbit,” says Satyaprakash. For this reason, “neutron star and black hole systems may be more powerful test beds for general relativity,” he says.
Also, gravitational waves and complementary observations by astronomers can explain what happens in the final stages before a merger. As tidal forces tear apart a neutron star, they can help the astrophysicist solve a long-standing mystery: what conditions are inside these ultra-compact objects.
The LIGO-Virgo collaboration began its current observations on April 1 and was expected to see approximately one black hole merger per week and one neutron star merger per month. So far, those predictions have come true; observatories have also observed several black hole mergers this month. “It’s just amazing,” says Kasliwal. “The universe is magnificent.” This article is reproduced with permission and was first published on April 26, 2019.
Black holes caught eating neutron stars for the first time. The stars had no chance against more massive black holes. Astronomers first observed a collision between a black hole and a neutron star, and then, 10 days later, they saw another.
Black holes caught eating neutron stars
Two Paths: Black holes and neutron stars are the two densest and most extreme bodies in the universe, and they both start out the same way: massive stars. When those stars run out of fuel, they explode into red supergiants that then explode as supernovae.
After that, stars either shrink to neutron stars or collapse into black holes, and the path they take depends on their original mass. Gravitational Waves: More than a century ago, Albert Einstein predicted that the motion of massive objects in the universe would cause tiny ripples in the fabric of space-time called gravitational waves.
He also predicted that those waves would be impossible to detect. In 2015, scientists at the Laser Interferometer Gravitational Wave Observatory (LIGO) proved that Einstein was right and wrong by recording the gravitational waves caused by the merger of two black holes.
Afeat that earned him the Nobel Prize in Physics. Since then, scientists have detected gravitational waves caused by more black hole mergers and mergers between pairs of neutron stars, but never between a black hole and a neutron star until now.
Using data collected by LIGO and the Virgo Interferometer in Italy, scientists have now discovered evidence for two of these collisions. Both incidents were detected in January 2020. The first occurred about 900 million light-years from Earth, while the second occurred about a billion light-years away.
Astronomers could not detect any light from the collision, suggesting that the black holes swallowed their respective neutron stars whole. These were not incidents where black holes chewed up neutron stars like Cookie Monster and threw chunks out.
LIGO Scientific Collaboration spokesman Patrick Brady said in a press release. “That ‘flying’ is what will produce the light,” he adds, “and we don’t think that has happened in these cases.”
Why It Matters?
The universe is filled with binary star systems in which two stars orbit the same point in space. It makes sense, then, that some of those pairs went extinct and became a black hole and a neutron star, but astronomers have never seen such a pairing.
Now that you have detected these two collisions, you know that the events are rare but possible. This is a spectacular milestone for the nascent field of gravitational wave astronomy, study co-leader Rory Smith of Monash University said in a news release.
“Neutron stars merging with black holes are among the most extreme events in the universe,” he continued. “Seeing these collisions opens up new avenues to learn about fundamental physics, as well as how stars are born, live and die.”
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