New Evidence of Gravitational Wave Background Permeating All of Spacetime - SciTechDaily

The signals from the pulsars measured with a network of global radio telescopes are affected by the gravitational waves and allow for the study of the origin of the background.

The results of a comprehensive search for a background of ultra-low frequency gravitational waves has been announced by an international team of astronomers including scientists from the Institute for Gravitational Wave Astronomy at the University of Birmingham.

The International Pulsar Timing Array (IPTA), joining the work of several astrophysics collaborations from around the world, recently completed its search for gravitational waves in their most recent official data release, known as Data Release 2 (DR2).

This data set consists of precision timing data from 65 millisecond pulsars – stellar remnants which spin hundreds of times per second, sweeping narrow beams of radio waves that appear as pulses due to the spinning – obtained by combining the independent data sets from the IPTA’s three founding members: The European Pulsar Timing Array (EPTA), the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), and the Parkes Pulsar Timing Array in Australia (PPTA).

These combined data reveal strong evidence for an ultra-low frequency signal detected by many of the pulsars in the combined data.

To identify the gravitational-wave background as the origin of this ultra-low frequency signal, the IPTA must also detect spatial correlations between pulsars.

Intriguingly, the first indication of a gravitational wave background would be a common signal like that seen in the IPTA DR2.

Whether or not this spectrally similar ultra-low frequency signal is correlated between pulsars in accordance with the theoretical predictions will be resolved with further data collection, expanded arrays of monitored pulsars, and continued searches of the resulting longer and larger data sets.

The IPTA DR2 analysis demonstrates the power of the international combination giving strong evidence for a gravitational wave background compared to the marginal or absent evidence from the constituent data sets.

Additionally, new data from the MeerKAT telescope and from the Indian Pulsar Timing Array (InPTA), the newest member of the IPTA, will further expand future data sets.

“The first hint of a gravitational wave background would be a signal like that seen in the IPTA DR2.

Then, with more data, the signal will become more significant and will show spatial correlations, at which point we will know it is a gravitational wave background.

We are very much looking forward to contributing several years of new data to the IPTA for the first time, to help achieve a gravitational wave background detection,” says Dr.

Given the latest published results from the individual groups who now all can clearly recover the common signal, the IPTA is optimistic for what can be achieved once these are combined into the IPTA Data Release 3.

Work is already ongoing on this new data release, which at a minimum will include updated data sets from the four constituent PTAs of the IPTA?

Maura McLaughlin of the NANOGrav collaboration says, “If the signal we are currently seeing is the first hint of a gravitational wave background, then based on our simulations, it is possible we will have more definite measurements of the spatial correlations necessary to conclusively identify the origin of the common signal in the near future.”.

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