What in the blazes is a 'blazar' and should we be worried that the oldest and biggest one in the universe is pointed directly at Earth?
“We present the discovery of PSO J030947.49+271757.31, the radio brightest (23.7 mJy at 1.4 GHz) active galactic nucleus (AGN) at z > 6.0.”
Well, that opening line from a new study published in Astronomy & Astrophysics tells us absolutely nothing about blazars that a non-astronomer can understand. Fortunately, we have Silvia Belladitta, a Ph.D. student at the University of Insubria in Italy and leader of the study, to explain it to us in somewhat simpler terms in a statement to Phys.org.
“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."
PSO J0309+27 was first discovered when Belladita and her colleagues looked at 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 the Wide-field Infrared Survey Explorer (WISE) space telescope. A bright object was isolated and named PSO J030947.49+271757.31 (PSO J0309+27 for short). Knowing its exact location, they then took measurements from the Large Binocular Telescope (LBT) in Arizona and NASA’s Sift space telescope to determine that it was an active galactic nucleus (AGN) – a black hole at the center of a galaxy that was consuming the stars around it. All exciting stuff, but one piece of data from the LBT made this a unique and mind-blowing discovery.
“In addition, the data obtained by LBT also confirmed that PSO J0309+27 is really far away from us, according to the shift of the color of its light toward red or redshift with a record value of 6.1, never measured before for a similar object."
OK, mind-blowing for astronomers. PSO J0309+27 is a supermassive black hole at the center of a galaxy and is a billion times more massive than our Sun. For an apples-to-apples (or AGN-to-AGN) comparison, the supermassive black hole at Milky Way’s center is only four million times more massive than the Sun. While PSO J0309+27's mass is impressive, its light is even more extraordinary. It means that the radar jets blasting out of PSO J0309+27 are pointed directly at Earth – THAT’S why it’s called a ‘blazar’. Any slight deviation would make it a barely detectable non-blazar AGN. At the distance of 13 billion light years, the third remarkable thing about PSO J0309+27 is that it’s barely a billion years older than the entire universe.
“Thanks to our discovery, we are able to say that in the first billion years of life of the universe, there existed a large number of very massive black holes emitting powerful relativistic jets. This result places tight constraints on the theoretical models that try to explain the origin of these huge black holes in our universe."
Yes that’s a big deal to Belladitta and her fellow astronomers, who are now anxiously awaiting the Vera C. Rubin Observatory in Chile coming online this year. The first objects they’ll most likely study are the 100 other known AGNs.
And finally … is Earth in any danger with the biggest and oldest blazar in the universe blazing its jets directly at us? Not a chance.
It’s about time we got some good news.