The largest map ever of active supermassive black holes in the universe has been released

Astronomers have charted the largest size of the universe ever with a new map of the active, supermassive black holes that live in the centers of galaxies. Ironically, gas-devouring black holes, called quasars, are some of the brightest objects in the universe.

The new map records the position in space and time of about 1.3 million quasars, the most distant of which shone when the universe was only 1.5 billion years old. (For comparison, the universe is now 13.7 billion years old.)

“This catalog of quasars is different from all previous catalogs in that it gives us a 3D map of the largest volume of the universe ever seen,” says map co-author David Hogg, a senior research scientist at the Flatiron Institute's Center for Computational Sciences. Astrophysicist in New York City and Professor of Physics and Data Science at New York University. “It's not the catalog with the largest number of quasars, and it's not the catalog with the best measurements of quasars, but it is the catalog with the largest total volume of the universe ever mapped.”

Hough and his colleagues show the map In a paper published in Astrophysical Journal. The lead author of this paper, Kate Storey-Fisher, is a postdoctoral researcher at the Donostia International Physics Center in Spain.

Scientists built the new map using data from the European Space Agency's Gaia space telescope. While Gaia's main goal is to map the stars in our galaxy, it also inadvertently detects objects outside the Milky Way, such as quasars and other galaxies, while scanning the sky.

“We've been able to make measurements of how matter gathered together in the early universe that were as precise as some of those measurements from major international survey projects — which is pretty remarkable considering we got our data as a bonus from the Milky Way — and the Gaia Center Project,” says Story-Fisher.

Quasars are powered by supermassive black holes at the centers of galaxies and can be hundreds of times brighter than the entire galaxy. When the black hole's gravity spins nearby gas, the process generates an extremely bright disk and sometimes jets of light that telescopes can spot.

Galaxies inhabited by quasars are surrounded by massive halos of invisible matter called dark matter. By studying quasars, astronomers can learn more about dark matter, such as how much it clumps together.

Astronomers can also use the locations of distant quasars and host galaxies to better understand how the universe expands over time. For example, scientists have already compared the new quasar map with the oldest light in our universe, the cosmic microwave background. When this light travels to us, it is bent by the interwoven web of dark matter, the same web drawn by quasars. By comparing the two, scientists can measure how tightly the material clumps together.

“It's been very exciting to see this catalog stimulate a lot of new science,” says Story-Fisher. “Researchers around the world use the quasar map to measure everything from the primordial density fluctuations that seeded the cosmic web to the distribution of cosmic voids to the motion of our solar system through the universe.”

The team used data from Gaia Data Release 3, Which contains 6.6 million quasar candidatesThe data is from NASA's Wide Field Infrared Survey Explorer and the Sloan Digital Sky Survey. By combining the datasets, the team removed contaminants such as stars and galaxies from the original Gaia dataset, and more accurately determined the distances to the quasars.

The team also created a map showing where dust, stars, and other disturbances are expected to obscure our view of some quasars, which is crucial to interpreting the quasar map.

“This catalog of quasars is a great example of how productive astronomical projects can be,” Hogue says. “Gaia was designed to measure the stars in our galaxy, but it also found millions of quasars at the same time, giving us a map of the entire universe.”