Synopsis: LIGO’s Black Hole Got the Boot

An analysis of data from LIGO’s second gravitational-wave event indicates that a supernova can impart a strong kick to the black hole it creates.

When a massive star dies, it explodes as a supernova that leaves a neutron star or black hole behind. But it remains unclear whether a newborn black hole can be sent scooting away from the event, because there’s not enough black hole velocity data to be certain. Richard O'Shaughnessy from the Rochester Institute of Technology, New York, and colleagues now say that such a “kicked” black hole looks possible. The team’s analysis of the second event recorded by the LIGO gravitational-wave detectors suggests that a natal kick must have been imparted to the more massive member of the duo of black holes that generated the waves.

Previous analysis of LIGO’s second event, known as GW151226, indicated that it was produced by the merger of two black holes with masses 8 and 14 times the Sun’s mass. Further, it suggested that the more massive object had a spin axis misaligned with the orbital axis of the pair by some 25 to 80 degrees. In their new kinematic analysis of the event, O'Shaughnessy and co-workers assume that the black hole pair formed from a binary star system in which both stars exploded as supernovae, as opposed to forming separately and later being brought together. They find that, in this scenario, where the spin and orbital axes start out aligned, the more massive black hole must have received a kick of more than 50 km/s from its supernova progenitor in order to produce the deduced spin–orbit misalignment. Such a large kick is challenging to explain within conventional supernova theory.

This research is published in Physical Review Letters.

­–Ana Lopes

Ana Lopes is a Senior Editor of Physics.


Features

More Features »

Announcements

More Announcements »

Subject Areas

AstrophysicsGravitation

Previous Synopsis

Atomic and Molecular Physics

Tracking a Trapped Ion Crystal

Read More »

Next Synopsis

Related Articles

Synopsis: 2D Maps of Solar Wind
Astrophysics

Synopsis: 2D Maps of Solar Wind

Maps of solar wind velocities derived from satellite images of the Sun’s corona could help researchers improve solar wind models. Read More »

Synopsis: Ideal Mergers for Measuring Cosmic Expansion
Cosmology

Synopsis: Ideal Mergers for Measuring Cosmic Expansion

Among gravitational-wave sources, the merger of a neutron star and a black hole may provide the most precise way to measure how fast the Universe is expanding. Read More »

Synopsis: A Closer Look at Cosmic Dust
Cosmology

Synopsis: A Closer Look at Cosmic Dust

Simulations provide a detailed picture of the emission of dust grains in our Galaxy, which is known to interfere with measurements of the cosmic microwave background. Read More »

More Articles