US scientists have used an innovative method of combining images from two optical telescopes to create the most detailed infrared image of the active galactic nucleus – the location of a supermassive black hole. Previously, for a similar purpose, the interferometry method was used to obtain images of black holes in the radio range with the Event Horizon Telescope (EHT). With optics everything is much more complicated, but it is clear and informative.
NGC 1068. Image Source: NASA
It is still possible to combine two images from optical telescopes in order to increase the resolution of the final image only with direct synchronization via optics and with relatively close telescopes. For example, such modes are possible on the VLT optical telescope complex, where equipment for optical interferometry was provided from the very beginning. Scientists from the United States are only taking the first steps in this direction, having created conditions for optical interferometric imaging at the LBT telescope in Arizona.
An LBT or Large Binocular Telescope is two mirrors placed side by side. In fact, these are twin telescopes, the diameter of each mirror reaches 8.4 m. Until last year, the telescopes were used separately, for example, observing the same object with different filters (at different wavelengths). For the first time, the interferometer mode was used to monitor the volcanoes of Jupiter’s satellite Io. The result inspired scientists so much that they decided to look at other objects in the Universe in the same way. In particular, they were interested in the details of the active galactic nucleus closest to the Milky Way, NGC 1068.
Active galactic nuclei are consequences of the massive fall of matter into supermassive black holes at the centers of galaxies. Black holes themselves are invisible in all ranges, but before matter falls on them, it heats up to millions of degrees and glows brightly in all ranges. These radiations interact with dust and gas near the centers of galaxies and even beyond them. This interaction has feedback that can only be seen with high resolution. For example, the LBT image shows the dependence of the movement of dust on radiation in the radio range and the feedback between them. Without an infrared image with record-breaking detail, this connection would have been impossible to see in such detail.
«The active galactic nucleus in NGC 1068 is particularly bright, so this was an excellent opportunity to test this method, the scientists explain. “These are the most accurate, highest-resolution images of an active galactic nucleus taken to date.”