NANOGrav Archives

July 6, 2023July 6, 2023 by Brian Koberlein

Did the Pulsar Timing Array Actually Detect Colliding Primordial Black Holes?

Illustration of merging black holes and their effect on pulsars and Earth. Credit: Daniëlle Futselaar (artsource.nl) / Max Planck Institute for Radio Astronomy

The universe is filled with gravitational waves. We know this thanks to the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which recently announced the first observations of long wavelength gravitational waves rippling through the Milky Way. The waves are likely caused by the mergers of supermassive black holes, but can we prove it?

June 24, 2023June 24, 2023 by Scott Alan Johnston

Early Black Holes Were Bigger Than We Thought

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.

June 19, 2023June 19, 2023 by Brian Koberlein

Astronomers Have Never Detected Merging Supermassive Black Holes. That Might Be About to Change

Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott Noble

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.