Gravitational wave interferometers like LIGO are deeply impressive engineering feats, perfected over the years to measure barely detectable ripples in space-time generated by massive cosmic objects.
But the cosmos has provided us with another tool with which we might be able to detect elusive gravitational wave signals. It is a type of dead star called pulsars, and the delays in its precisely timed flashes could be a clue to the bottom of the Universe’s gravitational waves: the buzz of billions of years of col. cosmic lesions and exploding stars.
Earlier this year, the NANOGrav collaboration announced that they could have detected this buzz. Now a second group, led by astrophysicists Boris Goncharov and Ryan Shannon, of the ARC Center of Excellence for Gravitational Wave Discovery (OzGrav) in Australia, has revealed its own results.
Although their findings are more conservative, the results are not inconsistent with the background of gravitational waves. This suggests that we may be trimming the right tree, after all, but there is still a lot of work to be done before a conclusive claim can be made.
“Recently, the U.S. Nanohertz Observatory for Gravitational Waves (NANOGrav) found evidence of the common spectrum component in its 12.5-year-old data set,” the researchers wrote in their work.
“Here we report on the search for the fund through the second publication of data from the Parkes Pulsar Timing Array. If we are forced to choose between the two NANOGrav models (one with a common spectrum process and one without), we find strong support for to the common spectrum process “.
Gravitational wave astronomy is still practically in its infancy. We detected gravitational waves using LIGO-Virgo interferometers here on Earth, the huge bumps generated by the collision of black holes and neutron stars. But there should be a much weaker signal surrounding the Universe: the bottom of the gravitational wave.
This is the collective signal accumulated throughout the history of the Universe. Every pair of black holes or colliding neutron stars, every collapsing supernova in the core, even the Big Bang itself, should have sent ripples that sounded through space-time.
After all this time, these waves would be weak and hard to find, but they are all expected to form a resonant “snoring” at the bottom of the Universe.
Now that we have confirmation that gravitational waves exist and can be detected (a discovery of only six years), scientists are looking for the background of gravitational waves. It could reveal one a lot on the history of the Universe: breaking it would be a great scientific breakthrough. And while that won’t be easy, the bracelets show a lot of promise.
It is a type of neutron star, which rotates at incredibly high speeds and is oriented so that it emits the emission beams of its poles as they do so, like a cosmic beacon. These millisecond pulses are so regular that we can use time delays for a range of potential applications. This is called the pulsation time matrix.
Because gravitational waves deform space-time, they should theoretically produce minimal delays in pulsating time. This is what the NANOGrav team found in their data and what the OzGrav team has also been looking for.
“The file [gravitational wave] the background stretches and reduces the temporal space between the pulsars and the earth, causing the pulsar signals to arrive a little later (stretch) or earlier (shrink) than otherwise it would happen if there were no gravitational waves, ”Shannon told ScienceAlert earlier this year.
The team analyzed data from the Murriyang radio telescope in Parkes, Australia, and found deviations at the time of the emission of pulsars consistent with what we would expect from the gravitational wave background. They also ruled out other potential sources of the signal, such as the interference of Jupiter and Saturn.
However, we do not yet have enough data to confirm that we are really looking at the background of gravitational waves, rather than the regular pulsar noise, for example. We need more observations and data to determine if the signal is correlated between all the pulsars in the sky, which will take much longer to work.
“To find out if the observed‘ common ’drift has a gravitational wave origin,” Goncharov said, “or if the gravitational wave signal is deeper in the noise, we need to continue working with new data from a number. growing number of pulse synchronization arrays around the world. “
This work, and that of NANOGrav earlier this year, are the first steps in making this detection. It’s an incredibly exciting time for gravitational wave astronomy.
The research has been published in The Astrophysical Journal Letters.