3C 348 is a giant elliptical galaxy. If we look at it in visible light, it is barely noticeable. However, at radio waves it emits about a billion times more energy than the Sun. Then the spectacle in the image above emerges.
Like the Milky Way and billions of other galaxies in space, 3C 348 is home to a central black hole. This is equivalent to 2500 million solar masses. From there, powerful and huge jets of plasma burst out, stretching over one and a half million light years. These are the ones that look like pink balloons in the image above.
These jets, discovered from radio data from the Karl Jansky Very Large Array (VLA) observatory, are formed by charged particles accelerated to near-light speeds and emanating from the vicinity of the black hole. Invisible in the optical range, they appear only at certain wavelengths, such as in radio.
The pink ray generator in the image is the Hercules Black Hole. It is the brightest radio-emitting object in the constellation of the same name.
Hercules A emits almost a billion times more energy than our Sun. Jets can travel so far that they eclipse the visible galaxy from which they emerge, forming giant radio galaxies, the largest known objects in the Universe.
Many more similar cases were found throughout the sky.
Connection
In a new study published in Nature Astronomy
We have discovered a connection between the region adjacent to supermassive black holes such as Hercules A, dominated by the innermost part of the jets of particles they emit, and their host galaxy. We see hints of a physical connection between both systems, despite their Homeric contrast in size and mass.Galaxy Core Activated
Supermassive black holes are relatively rare, but we believe that all galaxies contain at least one (and sometimes two) at their core. Our own galaxy, for example, contains at its center the supermassive black hole Sagittarius A*.
ESA/NASA, AVO project and Paolo Padovani
Sometimes a supermassive black hole, thanks to its powerful gravitational field, begins to attract gas and cosmic dust, and the core of its galaxy becomes active. These materials form a hot disk of material surrounding the black hole, called an accretion disk. Everything, in turn, is surrounded by a torus of interstellar dust located a little further away.
Some of these active galactic nuclei emit powerful jets of particles emanating from the accretion disk, accelerated to speeds close to the speed of light. We were able to study the orientation and morphology of these jets thanks to high-resolution VLBI, a very ingenious observing system.
Very long baseline interferometry (VLBI) uses a large number of radio antennas simultaneously, turning them into a giant radio telescope the size of Earth. This is the same technique that was used to photograph the halo around the supermassive black hole M87 or Sagittarius A*.
Jets of particles from black holes
The origin of giant jets is in the region adjacent to the black hole, an area the size of small (several light years). However, they extend immensely, reaching sizes of millions of light years.
Observation of this region surrounding black holes is only possible using VLBI; We won’t be able to see it even with the best optical telescopes. Analysis of these exciting regions allowed us to learn the orientation of the jets of particles emitted by black holes. Once we discover this orientation, we can also find out what the orientation of the accretion disk from which they come is. This is how we know the properties of a black hole.
Once we learn about them, we compare them with their parent galaxies. The difference in magnitude between one thing and another is so huge that we didn’t expect to find a connection. It’s like comparing a grain of sand to Saturn and hoping that there is some connection between them. But there is. We’ve found a disturbing and surprising clue that connects them.
Parent galaxies for black holes
NASA, ESA, A. Lessing (Stanford University), E. Baltz (Stanford University), M. Schara (AMNH), J. DePasquale (STScI), and Roux-Saint Lou.
A galaxy is a three-dimensional space object consisting of millions of stars. When we observe them in optical or infrared telescopes, the visible image, the result of the projection, is a spiral or ellipse. In any of these observations, we can trace its luminous profile and identify the semi-major and minor axes of a two-dimensional shape.
In our studies, we observed which direction the semi-minor axis of the galaxy’s two-dimensional shape takes and compared it with the orientation of the jets emitted by black holes in active nuclei. Here! The galaxy is pointed in the same direction as the jets of particles emitted by the supermassive black hole at its core. Is this a coincidence? This almost never happens.
Let’s not forget the size difference between the black hole (on the order of light years) and the host galaxy (millions of light years in size) to understand the surprising nature of the discovery.
And why are the orientations of both the same?
A prioriwe would expect to see a correlation between the jets and the region adjacent to the black hole, but not with the entire galaxy.
elliptical galaxies
Could this result tell us anything more about the process of galaxy formation?
In our studies, we also found that the majority of active galactic nuclei with jets observed with VLBI correspond to elliptical galaxies. These types of galaxies are very massive and very bright, and have few new stars. The discovery provides evidence in favor of the hypothesis that spiral galaxies formed by young stars can merge to form elliptical galaxies, with the galactic nucleus being activated during the merger process.
The final physical interpretation of our results currently remains a mystery, but it is not the only one. Recently, the James Webb Space Telescope discovered supermassive quasars (hence with supermassive black holes) that formed long before the expected time and it is not possible to explain how this happened.
This, together with our results, indicates that our knowledge of how galaxies form and evolve, and the role that black holes play in this, needs to be updated.