A new study has examined the possibility of creating an image of the gravitational sky using millihertz gravitational waves. Different known sources of gravitational waves were considered, such as binary white dwarfs, neutron stars, and black hole mergers. These waves were analyzed and filtered through the estimated capabilities of the Advanced Millihertz Gravitational Wave Observatory (AMIGO) and the future LISA mission.
LISA, or the Laser Interferometer Space Antenna, is a gravitational wave observatory similar to LIGO, but with much longer arms that can span millions of kilometers. This allows it to detect millihertz waves, capturing not only black hole mergers but also supermassive black hole captures and possibly the remnant gravitational waves from the Big Bang.
Using the data provided by LISA, astronomers will be able to create an image of the gravitational sky, similar to how radio astronomers create images from radiofrequency light. By assigning colors to different frequency ranges, a false-color image of the gravitational sky emerges.
Although the launch of LISA is still a decade or more away, the image of the gravitational sky is already present, rippling through the universe. This image surrounds us and is part of our everyday lives. With patience and ingenuity, the day will come when we finally witness these waves crashing on our cosmic shore.
Reference: Szekerczes, Kaitlyn, et al. “Imaging the Milky Way with Millihertz Gravitational Waves.” The Astronomical Journal 166.1 (2023): 17.