In 2019, a team of astronomers led by Dr. Samantha Oates of the University of Birmingham discovered one of the most powerful transients ever seen – where astronomical objects change their brightness over a short period. Oates and her colleagues found this object, known as J221951-484240 (or J221951), using the Ultra-Violet and Optical Telescope (UVOT) on NASA’s Neil Gehrels Swift Observatory while searching for the source of a gravitational wave (GW) that was thought to be caused by two massive objects merging in our galaxy.
Gravitational waves don’t travel through space and time. They are ripples in the fabric of spacetime itself. This is why they are so difficult to detect. We can only observe them by closely watching how objects bent and stretched within spacetime. But despite their oddness, gravitational waves behave in many of the same ways as light, and astronomers can use that fact to study cosmic expansion.
Gravitational astronomy is a relatively new discipline that has opened many doors for astronomers to understand how the huge and violent end of the scale works. It has been used to map out merging black holes and other extreme events throughout the universe. Now a team from Cal Tech’s Walter Burke Institute for Theoretical Physics thinks they have a new use for the novel technology – constraining the properties of dark matter.
Every large galaxy in the nearby universe contains a supermassive black hole at its core. The mass of those black holes seems to have a relationship to the mass of the host galaxies themselves. But estimating the masses of more distant supermassive black holes is challenging. Astronomers extrapolate from what we know about nearby galaxies to estimate distant black hole masses, but it’s not a perfectly accurate measurement.
An astrophysicist at the University of Colorado, Boulder, Joseph Simon, recently proposed that there might be a better way to measure black hole mass, and his model indicates that early black holes may be much larger than other predictions suggest.
Gravitational wave astronomy currently can only detect powerful rapid events, such as the mergers of neutron stars or stellar mass black holes. We’ve been very successful in detecting the mergers of stellar mass black holes, but a long-term goal is to detect the mergers of supermassive black holes.
Researchers have discovered an exciting new source of gravitational waves. They are the remnants left over from a supernova explosion, and they may just reveal the secrets to how those explosions work.
When two black holes collide, they don’t smash into each other the way two stars might. A black hole is an intensely curved region of space that can be described by only its mass, rotation, and electric charge, so two black holes release violent gravitational ripples as merge into a single black hole. The new black hole continues to emit gravitational waves until it settles down into a simple rotating black hole. That settling down period is known as the ring down, and its pattern holds clues to some of the deepest mysteries of gravitational physics.
With greater sensitivity, astronomers will be able to trace GW events back to their source and use them to probe the interiors of exotic objects and the laws of physics. As part of their Voyage 2050 planning cycle, the European Space Agency (ESA) is considering mission themes that could be ready by 2050 – including GW astronomy. In a recent paper, researchers from the ESA’s Mission Analysis Section and the University of Glasgow presented a new concept that would build on LISA – known as LISAmax. As they report, this observatory could potentially improve GW sensitivity by two orders of magnitude.
Fast Radio Bursts (FRBs) were first detected in 2007 (the Lorimer Burst) and have remained one of the most mysterious astronomical phenomena ever since. These bright radio pulses generally last a few milliseconds and are never heard from again (except in the rare case of Repeating FRBs). And then you have Gravitational Waves (GW), a phenomenon predicted by General Relativity that was first detected on September 14th, 2015. Together, these two phenomena have led to a revolution in astronomy where events are detected regularly and provide fresh insight into other cosmic mysteries.
In a new study led by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), an Australian-American team of researchers has revealed that FRBs and GWs may be connected. According to their study, which recently appeared in the journal Nature Astronomy, the team noted a potential coincidence between a binary neutron star merger and a bright non-repeating FRB. If confirmed, their results could confirm what astronomers have expected for some time – that FRBs are caused by a variety of astronomical events.
According to new research led by the Advanced Propulsion Laboratory at Applied Physics (APL-AP), GWs could also be used in the Search for Extraterrestrial Intelligence (SETI). As they state in their paper, LIGO and other observatories (like Virgo and KAGRA) have the potential to look for GWs created by Rapid And/or Massive Accelerating spacecraft (RAMAcraft). By combining the power of these and next-generation observatories, we could create a RAMAcraft Detection And Ranging (RAMADAR) system that could probe all the stars in the Milky Way (100 to 200 billion) for signs of warp-drive-like signatures.