Astrophysicists from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) Collaboration have found evidence for gravitational waves that oscillate with periods of years to decades, according to a series of papers published in the Astrophysical Journal Letters.
In 1916, Albert Einstein proposed space-time as a four-dimensional fabric, and that events such as exploding stars and merging black holes create ripples — or gravitational waves — in this fabric.
Almost a century later, in 2015, astrophysicists from the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations made the first direct observation of gravitational waves caused by the collision of two stellar-mass black holes.
The new research from the NANOGrav Collaboration is the first evidence of gravitational waves at very low frequencies.
The authors transformed our region of the Milky Way Galaxy into an immense gravitational-wave antenna using millisecond pulsars.
NANOGrav’s endeavor involved collecting data from 68 pulsars, fashioning a pulsar timing array — a distinctive type of detector.
The researchers examined 15 years of data from three radio observatories: Arecibo Observatory in Puerto Rico, the Green Bank Telescope in West Virginia and the Very Large Array in New Mexico.
“It’s incredibly exciting to have helped open a new window to the Universe,” said SETI Institute researcher Michael Lam.
The team’s analysis provides evidence that the variations in the ‘ticking rate’ of such millisecond pulsars are caused by low-frequency gravitational waves.
The spatial distortion from the gravitational waves creates the appearance that the pulsars’ radio-signal ticking rates are changing.
But really, it’s the stretching and squeezing of space between Earth and the pulsars which causes their radio pulses to arrive at Earth billionths of seconds earlier or later than expected.
“These are by far the most powerful gravitational waves…
Read the full article here