For decades, scientists have used networks of pulsars to search for a faint, background gravitational-wave signal that should pervade our universe. What have they found so far, and what can we expect in the future? A new publication details the possibilities.
Humming in the Background
Mrk 739 is an example of a galaxy merger where the two nuclei at the center of the newly-formed galaxy are still in the process of merging. [SDSS]In recent years, the LIGO and Virgo gravitational-wave detectors have clocked dozens of observations of stellar-mass black hole binary mergers. But what about larger black holes?
When galaxies collide, the supermassive black holes at their centers should also form binaries, inspiral, and merge. The combination of all inspiraling supermassive black hole binaries across the universe should produce a deep background hum of gravitational waves — a signal that we could detect, with the right tool. Enter: pulsar timing arrays (PTAs).
PTAs rely on the remarkably consistent timing of flashes of light from a network of spinning neutron stars — pulsars — to measure the stretching of the spacetime in which these pulsars are embedded.
An artist’s illustration showing how a network of pulsars could be used ...