Scientists have discovered the most ancient and distant “blazar,” a galaxy with a supermassive black hole that spews out mind-boggling amounts of light, at the edge of space and time. The object is roughly 13 billion light years away, but scientists were able to detect it because it is so “radio-loud,” meaning it is incredibly luminous even from afar.
A team led by Silvia Belladitta, a graduate student at the University of Insubria in Italy, announced the discovery of the blazar on Friday in the journal Astronomy & Astrophysics. Named PSO J030947.49+271757.3 (or PSO J0309+27 for short), it is the first known blazar at such a high “redshift,” which is a scale that measures the distance of luminous objects based on the distorted color of their light.
The blazar has a redshift of 6.1, which has never been measured before for a similar object, explained Belladitta and her advisors, Alberto Moretti and Alessandro Caccianiga, in an email. “At this redshift (6.1), we are observing the Universe as it was 900 million years after the Big Bang,” the team noted, which adds up to “less than one tenth of its life” of 13.8 billion years.
Blazars are a special class of active galactic nuclei (AGN), which are galactic centers defined by supermassive black holes that feed on large volumes of infalling gas, dust, and stars. As this material falls toward the black hole, it becomes extremely hot and energetic, sparking the release of luminous jets of matter and radiation that travel close to the speed of light. This transformation into an AGN can create explosive beams that are forceful enough to punch holes clear through galaxy clusters.
What separates blazars from regular AGN is their orientation toward Earth: In order to be considered a blazar, the jets from these objects have to be pointed directly at us. As a result, they are among the brightest objects in the sky, and can be used to estimate the overall population of similarly radiant AGN.
“The central point of our discovery is that the observation of PSO J0309+27 allows us to quantify, for the first time, the number of AGN with powerful relativistic jets present in the primordial universe,” Belladitta's team said. For each observed blazar, she added, “there must be 100 similar AGN with the jets pointed elsewhere, and therefore too weak to be seen directly.”
Belladitta and her colleagues were able to spot PSO J0309+27 by combining data from several different observatories. First, the team examined bright radio sources captured by the NRAO’s Very Large Array (VLA) in New Mexico, the Panoramic Survey Telescope and Rapid Response System in Hawaii (Pan-STARRS), and a space telescope called the Wide-field Infrared Survey Explorer (WISE).
Those results revealed the existence of PSO J0309+27, but it took measurements by the Large Binocular Telescope (LBT) in Arizona to confirm that this object is by far the most distant and ancient blazar ever observed. Further examination of its emissions, sourced from NASA’s Swift space telescope, showed that it is also “the most powerful radio-loud AGN ever discovered” at this distance, according to the study.
“The spectrum that appeared before our eyes confirmed first that PSO J0309+27 is actually an AGN, or a galaxy whose central nucleus is extremely bright due to the presence, in its center, of a supermassive black hole fed by the gas and the stars it engulfs,” Belladitta's team said.
The combined observations enabled the team to estimate that the supermassive black hole at the heart of PSO J0309+27 is about a billion times more massive than the Sun. By comparison, the supermassive black hole at the center of the Milky Way is puny, at only four million times the mass of the Sun.
The discovery of PSO J0309+27 sheds literal light on the origins of supermassive black holes, which are now abundant throughout the universe and influential to its evolution. What’s more, the team predicted that other ancient blazars are likely to be discovered as a hyper-sensitive generation of telescopes comes online in the coming years.
"The very important discovery of PSO J0309+27 sets the basis for expanding our knowledge on this particular class of AGN, on the primordial Universe and on the very distant supermassive black holes,” the team noted. “But only with new generation of telescopes, like the Vera Rubin Observatory or the Square Kilometer Array, we will be able to observe hundreds of blazars at redshift equal and/or larger than that of PSO J0309+27 and give more firm results.”
Those facilities will put the distant universe into sharper focus, enabling unprecedented insights about how we ended up with our modern cosmic surroundings.
Update : This article has been updated to include comments from lead author Silvia Belladitta and co-authors Alberto Moretti and Alessandro Caccianiga.