A doctoral student at the University of Oklahoma, graduate and undergraduate research assistants, and an associate professor in the Homer L. Dodge Department of Physics and Astronomy of the College of Arts and Sciences of the The University of Oklahoma are the lead authors of an article describing a “shift in outlook” blazar – a powerful active galactic nucleus powered by a supermassive black hole at the center of a galaxy. The article is published in The Journal of Astrophysics.
Hora D. Mishra, a Ph.D. student and faculty member Xinyu Dai are the main authors of the article, along with Christopher Kochanek and Kris Stanek at Ohio State University and Ben Shappee at the University of Hawaii. The article presents the findings of researchers from 12 different institutions who participated in a two-year collaborative project involving the collection of spectra or imaging data in different electromagnetic bands. The OU team led the analysis effort of all data collected as part of the collaboration and mainly contributed to the interpretation of the analysis results, assisted by the graduate student of the OR Saloni Bhatiani and undergraduates Cora DeFrancesco and John Cox who performed ancillary analyzes of the project.
Blazars, explains Mishra, who is also president of Lunar Sooners, appear as rays of light or parallel particles, or jets, pointing at observers and radiating at all wavelengths of the electromagnetic spectrum. These jets cover distances of the order of a million light years and are known to impact the evolution of the galaxy and the cluster of galaxies in which they reside via radiation. These characteristics make blazars ideal environments for studying jet physics and their role in the evolution of galaxies.
“The Blazars are a unique type of AGN with very powerful jets,” she said. “Jets are a mode of radio feedback and due to their scales, they enter the galaxy in their large-scale environment. The origin of these jets and the processes leading to the radiation are not well known. study of blazars allows us to understand these best jets and how they are connected to other components of the AGN, such as the accretion disk. These jets can heat and move gas in their environment affecting, for example, training stars in the galaxy.
The team’s article highlights the results of a campaign to investigate the evolution of a blazar known as B2 1420 + 32. At the end of 2017, this blazar exhibited a huge optical flare, a phenomenon captured by the All Sky Automated Survey for SuperNovae telescope array.
“We followed this by observing the evolution of its spectrum and light curve over the next two years and also retrieved the archival data available for this object,” Mishra said. “The campaign, with data spanning over a decade, has yielded some of the most exciting results. We see for the first time dramatic variability in the spectrum and multiple transformations between the two subclasses of blazar for a blazar, thus giving it the name of “change-look at ‘blazar.”
The team concluded that this behavior is caused by the dramatic changes in continuous flow, which supports a long-proposed theory that separates blazars into two main categories.
“In addition, we are seeing several very large multiband flares in the optical and gamma bands at different time scales and new spectral characteristics,” Mishra said. “Such extreme variability and spectral characteristics require dedicated research for more blazars, which will allow us to use the dramatic spectral changes observed to reveal AGN / jet physics, including how dust particles around supermassive black holes are destroyed by the enormous radiation from the central motor and how the energy of a relativistic jet is transferred into the dust clouds, providing a new channel connecting the evolution of the supermassive black hole to its host galaxy.
“We are very excited by the results of finding a changing-looking blazar that transforms not once, but three times, between its two subclasses, from the dramatic changes in its continuous show,” a- she added. “In addition, we see new spectral characteristics and unprecedented optical variability. These results open the door to more such studies on highly variable blazars and their importance in understanding the physics of AGNs.”
“It is really interesting to see the emergence of a forest of iron emission lines, suggesting that nearby dust particles were evaporated by the strong radiation from the jet and released free iron ions in the clouds. Transmitters, a phenomenon predicted by theoretical models and confirmed in this blazar explosion, ”Dai said.
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