Now, a team of astronomers, led by Matus Rybak, has discovered [1] just that. They detected millimeter waves coming from a supermassive black hole in the galaxy RXJ1131-1231, one of the most studied quasars found in the constellation Crater. This groundbreaking study leveraged data gathered by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope located in the Atacama Desert of northern Chile. It is a tremendous historic breakthrough in our understanding of these new cosmic phenomena.
As part of this research, in 2015 the team began a search for cold gas in the galaxy RXJ1131-1231. Belgian/Dutch researchers Dominique Sluse from Leuven and Frédéric Courbin from Barcelona were the driving forces behind this mission. In 2020, their unique long-term study made its final close. They measured how the brightness of the quasar changed over time and found that these changes occurred at different times in three images of the same galaxy. An intervening galaxy serves as a gravitational lens. In a clever touch, the device automatically magnifies the quasar, creating a stunning “double zoom” effect.
The Role of Macrolensing
The galaxy RXJ1131-1231 has an entrancing configuration. When another galaxy falls between it and Earth, the combination creates the striking phenomenon of macrolensing. This gravitational lensing effect makes the quasar look three times larger than its real size. Matus Rybak explained the concept succinctly:
“With this ‘double zoom’ (the magnification by the galaxy and that by the star), it’s as if you’re placing two magnifying glasses on top of each other,” – Matus Rybak.
This complex arrangement provides astronomers an opportunity to study the quasar’s light with a detail never before achieved. The space lensing effect increases perceived brightness by an order of magnitude. It enables researchers to identify changes in brightness that they otherwise would overlook.
Insights from the ALMA Telescope
Famed for its incredible sensitivity to (sub)millimeter radiation, the ALMA telescope was key to this important discovery. Situated in the high-altitude plateau of northern Chile, ALMA provided the necessary sensitivity and resolution to study the faint emissions from the supermassive black hole within RXJ1131-1231.
Rybak and his colleagues’ observations revealed that the quasar flickered on timescales of years, suggesting dynamic interactions surrounding the black hole. This long-term monitoring campaign of brightness variations is opening up thrilling new discoveries. It enriches our intellectual grasp of cosmic phenomena, especially those connected to black holes and gravitational lensing.
This is just a tiny glimpse at the team’s efforts over the past 17 years that showcases their dedication to pushing the field forward. Rybak noted the significance of their findings:
“That’s a smoking gun for microlensing, a phenomenon that occurs when a star is located between the foreground galaxy and the observer,” – Matus Rybak.
Pioneering Research in Microlensing
Matus Rybaks team has done very important work to the field of microlensing studies. Despite these other efforts, they were the first to use visible light for this purposes—and as far back as 2008. Their most recent effort continues that trend, deepening our knowledge of how space’s greatest giants affect the fabric of space-time itself.
That they can even track brightness variations over dozens of images of the same quasar is a testament to their skill and collaborative prowess. Astronomers study these changes to learn more about the shape of gravitational lenses themselves. They work to understand the propagation of light in extreme regimes.