Even with advanced technology and decades-long space research, many aspects of the universe still largely remain a mystery. Observing the universe from thousands and millions of light-years away and limited understanding of Physics can be a hurdle, but our scientists are always trying to learn more.
One such space phenomenon is gravitational waves. In a promising new study, scientists think they have found a faint background of gravitational waves in the universe. But the data is very new and will require more corroboration.
Theoretical physicists have posited many theories about it, but it is still one of the least observed in the field. Gravitational waves send disturbances in the spacetime curvature. They are created when massive objects are in motion, not mere asteroids or comets, but huge black holes or collisions of galactic scale. Though it was initially posited in the early 1900s, it wasn’t until late 2010s that actual proof of the phenomenon was observed.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) made the discovery. Then, there is North American Nanohertz Observatory for Gravitational Waves (NANOGrav) where scientists are constantly working on discovering more about the waves.
When galaxies collide and black holes merge, they orbit each other very quickly in their last moments. This produces rapid and strong gravitational waves. However, the other gravitational waves that ripple across our universe are almost never rapid or strong.
Most of the gravitational waves are very faint echoes of energy and radiation emitted out of black hole orbits that aren’t merging. These orbits are slow and create a faint background of such waves.
Detecting these waves can be tough. NANOGrav works on observing radio pulses from rapidly rotating neutron stars which are known as millisecond pulsars. These pulsars are fairly regular but some slight shift in pulse rate can occur due to relative motion. However, the drawback is that the background gravitational waves oscillate very slowly. It takes years to observe a shift of the pulsars due to their speed and distance.
In the latest study, around 45 millisecond pulsars were found to have very stable pulse rates. Then any spurious noise effects were filtered out. In the background, they saw a signal of gravitational waves with an oscillation period of about a year. The problem lies in proving that the signals observed indeed originated from gravitational waves.
NANOGrav has been observing pulsars for dozens of years and only now the researchers are able to publish any results. It looks like it will have to keep up with its observation for a dozen more years in order for us to create any concrete proof of gravitational waves forming this background.