Astronomers have detected gravitational waves. Now they want to see the cosmic ocean

The Green Bank Telescope in West Virginia is helping with the search for the background of gravity.

The Green Bank Telescope in West Virginia is helping with the search for the background of gravity.
Photo: ANDREW CABALLERO-REYNOLDS / AFP via Getty Images (Getty Images)

Utilizing a signal from dozens of fast-moving, dead stars, astrophysicists approached their goal to detect a background rumble of gravitational waves in the universe.

When the existence of gravitational waves was confirmed in 2016, opened up a new field of astrophysical research. Two black holes collided and sent a ripple into the space-time tissue detected on Earth as it caused a twist in the sensitive instruments of the Laser Interferometer Gravitational-Wave Observatory. Since then, scientists have picked up more gravitational waves produced by massive crushing, but they have also been looking for ways to see the so-called gravitational wave background. To use a metaphor: we have detected large waves that rocked our planetary boat, and now we want to see all the turbulent waves ejected into the cosmic ocean.

Last month, the North American Nanohertz Observatory for Gravity Waves took place published his latest dataset in The Astrophysical Journal Letters. The data – 12 and a half years of it – were compiled from observations by the Green Bank Telescope in West Virginia and the recently collapsed the Arecibo Observatory in Puerto Rico. In the paper a drawing pattern is described in the light of 45 pulses. It is a step in the direction of the background of the gravitational wave.

“What we find specifically is a low frequency signal, and it is a common signal among all pulses in the series,” said Joseph Simon, an astrophysicist at the University of Colorado Boulder and lead author of the recent article. a press said. conference today. Simon said the signal “is what we expect the first hints of the background of the gravitational wave to look like.”

Pulsars are the dense, spinning remnants of some dead stars. Millisecond pulsars rotate very fast – hundreds of times per second – and a select few do so reliably enough to enable scientists to catalog the slight changes in the relative position of our planet to the pulsars. Using the radio wave pulses of the Milky Way’s pulses in an array, the team conjured up a network of galaxy-sized detectors for low-frequency gravitational waves generated by the orbits of supermassive black holes rather than their collisions. The gravity background the team is looking for looks more like a constant, mumbling in space-time than an isolated blip like the one LIGO detected in 2016.

The array consists of pulses distributed across the Milky Way.

The array consists of pulses distributed across the Milky Way.
Photo: MARIANA SUAREZ / AFP via Getty Images (Getty Images)

Gravity waves are predicted by general relativity. Decades of astrophysical analysis have concluded that such waves would cause changes in the timing of the light of the pulsars reaching the earth. A gravity wave background will affect the light we receive from the pulsars based on each’s location and relative position, and a certain correlated pattern in changes in light, would indicate a gravitational wave background. The team did not officially find the pattern, but they think they noticed the beginning of it.

Although astrophysicists have been examining more than twelve years of data from their range of pulses, they still need more time and more pulses to be sure of the pattern. The waves that the team documents have much longer wavelengths than the gravitational waves that LIGO detected in 2016, and the research progress was therefore gradual.

One challenge is that the pulses of the pulsars are set up using atomic clocks, which can lose their accuracy. However, according to recent data, according to Scott Ransom, a staff astronomer at the National Radio Astronomy Observatory and co-author of the recent article, errors with the atomic clock were ruled out.

Ransom compares the gravitational waves to waves in the ocean of space-time, coming from different sources near and far. The gravitational waves disrupt each other in the air and move against an earth bouncing in the ocean, stretching the planet so slightly together.

“What we can deduce from this is just whether you can see that the ocean is calm or rough,” Ransom said in a phone call. “We can get a lot of information about the entire history of the universe and how galaxies merge and interact by just seeing this background signal.”

Both Simon and Ransom mourn the loss of the Arecibo Observatory radio dish, which collapsed in December after two cable failures. The research team pulled data from the observatory until the first cable broke, and the recent article only included data until 2017. Their current data set provides some sort of aftermath of Arecibo, as it will contribute to the search for a gravity wave background. for years to come.

.Source