Astronomers monitor an active galaxy roughly 1 billion light years away

A team of international astronomers recently carried out extensive high-time resolution optical monitoring of an active galaxy that lies roughly 1 billion light years away from Earth.

NASA defines active galaxies as the ones having extraordinarily luminous cores powered by supermassive black holes containing millions or even billions of times the mass of the sun. As gas falls toward these supermassive black holes, it settles into an accretion disk and heats up. Near the brink of the black hole, some of the gas blasts out of the disk in jets moving in opposite directions at nearly the speed of light.

The distant galaxy, named BL Lacertae (BL Lac), is classified as a blazer - the highest-energy type of active galaxy that emits light across the spectrum, from radio to gamma rays. An analysis of the high-cadence optical observations was critical to understanding the high-energy observations from NASA's Fermi Gamma-ray Space Telescope.

The international collaboration, known as the Whole Earth Blazar Telescope (WEBT), used 37 ground-based telescopes throughout the world including the BYU West Mountain Observatory to monitor the active galaxy.

BYU research professor of physics and astronomy Mike Jonerone, one of the astronomers contributing to the project, and BYU undergraduate student Gilvan Apolonio secured over 200 observations of the BL Lac galaxy using the 0.9-meter reflecting telescope at BYU's West Mountain Observatory. Their measurements were combined with observations made by WEBT scientists.

Using the WEBT observations made in the summer of 2020, astronomers discovered surprisingly rapid oscillations of brightness in the central jet of BL Lac. The scientists attribute these cycles of brightness change to twists in the jet's magnetic field.

"It is noteworthy that in this age of giant telescopes and space-based research, it is still necessary to rely on modest-sized and well-equipped facilities like we have available at BYU to explore the unknown reaches of the Universe," Joner said in a statement.

Their findings were recently published in the scientific journal Nature.