New gravitational wave maps reveal hidden black holes and cosmic structures

New gravitational wave maps reveal hidden black holes and cosmic structures
by Simon Mansfield
Melbourne, Australia (SPX) Dec 03, 2024

Astronomers from Swinburne University of Technology have led an international effort to produce the most detailed maps of gravitational waves in the universe. This research has also resulted in the creation of the largest galactic-scale gravitational wave detector and uncovered further evidence of a "background" of gravitational waves. These subtle ripples in spacetime offer insights into some of the universe's major mysteries.

Three studies published today delve into the roles of the largest black holes in shaping the universe and uncovering the cosmic structures they left behind.

Dr. Matt Miles, lead author of two studies and a researcher with OzGrav and Swinburne, highlighted the significance of this work: "Studying the background lets us tune into the echoes of cosmic events across billions of years. It reveals how galaxies, and the universe itself, have evolved over time."

Unprecedented gravitational wave detection

The research captured a stronger gravitational wave signal from merging supermassive black holes than similar experiments worldwide, and in one-third of the time.

"What we're seeing hints at a much more dynamic and active universe than we anticipated," said Dr. Miles. "We know supermassive black holes are out there merging, but now we're starting to ask: where are they, and how many are out there?"

A detailed map with unexpected findings

Using a pulsar timing array, the researchers developed an advanced gravitational wave map, revealing a surprising anomaly - an unexpected hotspot in the signal. This may indicate a directional bias or a unique gravitational wave source.

Rowina Nathan, lead author of one study and a researcher with OzGrav and Monash University, explained the significance of the findings:

"The presence of a hotspot could suggest a distinct gravitational wave source, such as a pair of black holes billions of times the mass of our Sun. Looking at the layout and patterns of gravitational waves shows us how our universe exists today and contains signals from as far back as the Big Bang. There's more work to do to determine the significance of the hotspot we found, but this is an exciting step forward for our field."

Precision observations with cutting-edge technology

The MeerKAT radio telescope in South Africa, one of the most advanced in the world, was instrumental in this research. Using the MeerKAT Pulsar Timing Array, scientists observed pulsars and timed their signals to nanosecond precision.

Pulsars, rapidly spinning neutron stars, serve as natural clocks. Their consistent pulses help detect tiny changes caused by gravitational waves. This innovative galactic-scale detector has revealed gravitational wave patterns that challenge existing theories.

Nathan noted that many assume gravitational wave signals are evenly distributed across the sky. "However, the galactic-sized gravitational wave detector formed by the MeerKAT pulsar timing array has allowed us to map the structure of this signal with unprecedented precision, which may reveal insights about its source."

Implications and future research

These findings raise important questions about the formation of massive black holes and the universe's early history. Continued observations with the MeerKAT array aim to refine gravitational wave maps and uncover hidden cosmic phenomena.

Kathrin Grunthal, a researcher at the Max Planck Institute for Radio Astronomy and co-author of one study, expressed the future goals of the project:

"By looking for variations in the gravitational wave signal across the sky, we're hunting for the fingerprints of the astrophysical processes shaping our universe."

The ongoing work promises to shed light on supermassive black hole evolution, galaxy formation, and potentially the universe's earliest events.