Published: Fri, June 02, 2017
Research | By Elizabeth Houston

Scientists spot rare gravity waves for the third time

Scientists spot rare gravity waves for the third time

"We have further confirmation of the existence of stellar-mass black holes that are larger than 20 solar masses-these are objects we didn't know existed before LIGO detected them", says MIT's David Shoemaker, the newly elected spokesperson for the LIGO Scientific Collaboration (LSC), a body of more than 1,000 global scientists who perform LIGO research together with the European-based Virgo Collaboration. Think of the black holes as two ice skaters, spinning around each other, but also spinning around their own axis.

"We can see the outlines of a population of black holes emerge", said Richard O'Shaughnessy, associate professor in RIT's School of Mathematical Sciences.

Alternatively, they may have formed separately, then come together in the densely packed star clusters in which their parent stars existed.

Gravitational waves are like the ripples on water.

Maybe that's not as unusual as it sounds.

The first-ever direct observation of gravitational waves was made in September 2015, and detected an event some 1.3 billion light-years away. LIGO's three detections are shown, plus a fourth possible detection that was not strong enough to confirm.

The third detection is described in a new paper accepted for publication in the journal Physical Review Letters.

The new gravitational wave signal is similar to LIGO's first two detections, both in its source - a binary black hole merger - and the overall mass of that source. These particular gravitational waves come courtesy of two black holes merging to become one that is about 50 times the mass of our sun. Only twin detectors located in Hanford, Wash. and Livingston, La., that are jointly run by California Institute of Technology and MIT, knew about it. Each detector is essentially a pair of vacuum tunnels positioned at a 90-degree angle, measuring 2.5 miles (4 km) per arm.

When the gravitational waves from the colliding black holes reached Earth in January, the LIGO detectors happened to be coming back online after a holiday break. Now that astronomers have detected three separate sets of gravitational waves in such a short period of time, it's nearly certain they'll keep seeing more of them. Black holes can spin counterclockwise and clockwise, like tornadoes, but can also tilt at angles tornadoes could never achieve.

How the new findings (GW170104) compare to preceding observations of binary black holes. Astrophysicists don't fully understand how such big black holes could have formed.

Arsene Wenger to remain Arsenal manager
Mertesacker was starting his first game of the season after spending the entire campaign on the sidelines with a knee injury. The 32-year-old had played only 37 minutes all season after coming off the bench in last weekend's win against Everton.

Trump waives law requiring US move its embassy to Jerusalem
Every president since President Bill Clinton has pushed off the move, citing national security concerns. Steinitz tells Israel's Army Radio station: "I think the time has come to put an end to this farce".

Philippine Minister Starts Damage Control After Duterte's China War Remark
Rodrigo Duterte's trip to Moscow started on Monday, the Philippine leader will spend five days in Russian Federation . According to Abella, Duterte maintains a two-track approach to the country's relationship with the Asian giant.

"It is inevitable that gravitational waves will be harnessed to create undreamt of new technologies". The first is that the black holes form together: If two stars already in a binary system eventually collapse into black holes, it makes sense that the black holes would remain in orbit around one another.

As was the case with the first two detections, the waves were generated when two black holes merged to form a larger black hole.

Further, the LIGO-Virgo team was able, through the new observation, to put tighter constraints on the mass of the graviton, the hypothesized particle that supposedly mediates the gravitational force (analogous to the way that the photon, for example, mediates electromagnetic force). As pairs of black holes spiral around each other, they also spin like a pair of ice skaters spinning individually while circling around each other.

Before merging together, two black holes can either spin in the same direction as they orbit each other - known as aligned spins - or they can spin in the opposing direction - known as non-aligned spins.

A mathematical simulation of the warped space-time near two merging black holes, consistent with LIGO's observation of the event dubbed GW170104. What's more, the latest ripples were caused by a collision that occurred 3 billion light years from Earth, much farther than the 1.3 and 1.4 billion light years of the first and second collisions, respectively. However, they caution, more data is needed to rule out either theory. With no sign of dispersion, the LIGO team can say that if gravitons exist and have mass, it has to be less than 7.7 x 10 electronVolts. The great distance of this merger also provides the most rigorous test to date for a specific part of Einstein's general theory of relativity - the lack of dispersion in gravitational waves.

This spring, astronomers discovered a "rogue" black hole moving speedily away from a distant galaxy known as 3C186, located some 8 billion light years from Earth. The outer contour for each represents the 90 percent confidence region.

For OzGrav's Deputy Director, Professor David McClelland, this latest discovery makes the impetus to continue work on upgrading the LIGO detector even more compelling. At that point, the instrument will undergo another round of sensitivity upgrades, including the swapping out of some mirrors for even more refined versions; additional improvements to laser power; and further efforts at noise reduction and improved computer control.

"We're extremely excited to have this detection of binary black hole mergers", Landry said. "By combining results from the large number of events that LIGO will observe in near future, we will be able to perform stringent tests of Einstein's theory", Parameswaran Ajith, the Principal Investigator of the nine-member ICTS team in LIGO said. Detectors are being planned in India and Japan as well.

This is why NSF started providing support for LIGO more than 40 years ago.

Be proactive - Use the "Flag as Inappropriate" link at the upper right corner of each comment to let us know of abusive posts.

Like this: