Numerical simulation of two black holes that inspiral and merge, emitting gravitational waves. Credit: N. Fischer, H. Pfeiffer, A. Buonanno, and the SXS Collaboration

A quick ‘bang’ signals the most massive gravitational-wave source yet

An international research collaboration including Northwestern University astronomers has witnessed the birth of an “intermediate-mass” black hole. This is the first conclusive discovery of an intermediate-mass black hole, an object which has long eluded astronomers. The cosmic event, its energy detected on Earth in the form of gravitational waves, is the most massive black hole merger yet observed in gravitational waves.

Two black holes likely collided and merged to create a more massive black hole with a final mass 142 times that of the sun, or 142 solar masses. This final black hole is the first to be found in an intermediate-mass range that lies between stellar-mass and supermassive black holes.

Another first is that the heavier of the two merging black holes, at 85 solar masses, is the first black hole so far detected within what is known as the “pair-instability mass gap.”

Researchers detected the gravitational-wave signal on May 21, 2019, with the National Science Foundation’s LIGO (Laser Interferometry Gravitational-wave Observatory (LIGO), a pair of identical, 4-kilometer-long interferometers in the United States, and Virgo, a 3-kilometer-long detector in Italy. The signal was dubbed GW190521.

Continue to the full Northwestern News story by Megan Fellman.

Professor Vicky Kalogera, principal investigator of Northwestern’s LIGO Scientific Collaboration group

Christopher Berry, CIERA Board of Visitors Research Professor, LIGO Scientific Collaboration Editorial Board reviewer for the discovery paper

Chase Kimball, LIGO Scientific Collaboration member and Northwestern astronomy Ph.D. student, contributed to the analysis of the astrophysical origins of GW190521 in the implications paper

Learn More

• LIGO Press Release, “A “bang” in LIGO and Virgo detectors signals most massive gravitational-wave source yet“
• EGO-Virgo Press Release, “Virgo and LIGO unveil new and unexpected black hole populations“
• Blog post by CIERA’s Christopher Berry: “GW190521—The big one“
• Visualization of heavy black-hole merger GW190521 by Max-Planck-Institut für Gravitationsphysik

Media Mentions of CIERA/Northwestern

• The New York Times, “These Black Holes Shouldn’t Exist, but There They Are” by Dennis Overbye

• CNN, “New type of black hole detected in massive collision that sent gravitational waves with a ‘bang’” by Ashley Strickland

• Inside Science, “Gravitational Waves Record Ancient Black Hole Merger Unlike Any Detected Before” by Charles Q. Choi

• Space.com, “Gravitational waves point scientists to elusive missing-link black hole” by Meghan Bartels

• Astronomy.com, “Scientists detect first mid-sized black hole via gravitational waves” by Caitlyn Buongiorno
• SciTech Daily, “Quick ‘Bang’ Signals the Most Massive Gravitational-Wave Source Ever Detected” as Northwestern recast with new visualizations
• Nature, “‘It’s mindboggling!’: Astronomers detect most powerful black-hole collision yet” by Davide Castelvecchi
• National Geographic, “Astronomers spot the biggest, strangest black hole collision ever found“
• Ars Technica, “Meet GW190521—a black-hole merger for the record books” by Jennifer Ouellette
• Astronomy Now, “Gravitational wave observatories detect biggest black hole merger yet“
• The Verge, “Astronomers say they’ve detected the most massive merger of two black holes ever discovered” by Loren Grush
• Live Science, “Largest black hole collision ever detected” by Rafi Letzter
• Science Alert, “Most Massive Black Hole Collision Detected Confirms Elusive Middleweight Black Holes” by Michelle Starr
• Futurism, “Astronomers Claim to Have Spotted the Most Massive Black Hole Merger Ever” by Victor Tangermann