Stars can no longer hide behind the light that feeds supermassive black holes in the infant universe. With the help of the James Webb Space Telescope (JWST), astronomers have observed for the first time the starlight from two early galaxies that harbor feeding supermassive black holes, or quasars. The findings could eventually help scientists better understand how supermassive black holes rapidly grow to masses equivalent to millions or billions of suns, and how they and their host galaxies evolve hand in hand.
“25 years ago, it was amazing for us to be able to observe host galaxies from 3 billion years ago using large ground-based telescopes,” said Knud Janke, a member of the team and a researcher at the Max Planck Institute for Astronomy. he said in a statement. “The Hubble Space Telescope allowed us to probe the maximum growth time of black holes 10 billion years ago. And now we have JWST available to see the galaxies in which the first supermassive black holes appeared.”
The team observed two of these so-called active galaxies, which look just as they did when the 13.8-billion-year-old universe was less than a billion years old. They were able to calculate both the mass of the galaxies and the mass of the supermassive black holes that feed the quasars, designated J2236+0032 and J2255+0251. The light from these two galaxies took 12.9 and 12.8 billion years to reach us, so it seemed to astronomers 870 and 880 million years after the Big Bang, respectively.
The observations revealed that the masses of galaxies are 130 billion and 30 billion times that of the sun, and the masses of the monstrous feeding black holes are 1.4 billion solar masses for J2236+0032 and 200 million solar masses for J2255+ 0251. This showed that the mass of these early galaxies and their central black holes are related in the same way observed in galaxies observed closer to the Milky Way and therefore more recent in time.
How do supermassive black holes grow with their galaxies? Quasars are some of the most extreme objects in the entire universe. Powered by supermassive black holes surrounded by gas and dust, some of which sticks to the black hole, some of which is ejected at velocities approaching the speed of light, quasars emit so much light that they can often outshine all the stars in Earth. the Galaxy. that welcome them . combined.
Almost all galaxies are thought to have a supermassive black hole at their center, but not all are quasars. For example, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), consumes so little matter that it is equivalent to a human eating a grain of rice every million years. So it’s not feeding enough to power a quasar.
The first quasar was detected in 1963, and since then scientists have unraveled the processes that fuel its immense emission of light. In the 2000s, the masses of galaxies and their supermassive black holes were found to be related, with the mass of the stars in a galaxy some 1,000 times greater than the mass of its central black hole. The relationship between the masses of supermassive black holes and their galaxies holds for galaxies with supermassive black holes with masses millions of times that of the Sun and for those with central black holes billions of times the mass of our star.
The connection between the mass of galaxies and the mass of their supermassive black holes may be related to the fact that both grow through a chain of galaxy mergers that ultimately causes the black holes at the center of these galaxies to collide violently. each other and create an even bigger black hole. Consequently, after numerous mergers, the mass of a galaxy will be about the average mass of the initial galaxy times the number of galaxies it merged with, while the mass of the central black hole will be about the mass of the black hole. initial black multiplied by the mass of the initial black hole by the same number, leading to a roughly linear relationship.
Another suggestion is that when a supermassive black hole feeds on enough material to become a quasar, the radiation it releases regulates the material available both to feed the quasar and to form new stars. So when the quasar runs out of food and stops growing, star formation slows down in that galaxy as well.
The supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), imaged by the Event Horizon Telescope in 2017 and launched in 2022. (Image credit: EHT Collaboration). Whatever the cause of this relationship, astronomers have so far been unable to determine whether it exists for galaxies and their supermassive black holes in the early universe. This is because while the brightness of quasars makes it possible to study them from billions of light-years away, it also makes it difficult to observe the faintest starlight from quasar-hosting galaxies.
Ground-based telescopes struggle to distinguish the light from quasars and the light from stars in their galaxies due to the effect of Earth’s atmosphere. From its position above the atmosphere, the Hubble Space Telescope has had some success extracting light from these galaxies when they are about 10 billion light-years away. But to do this in earlier, more distant galaxies, astronomers had to wait for the most powerful space telescope ever put into orbit, the JWST. Quasars J2236+0032 and J2255+0251 were observed with JWST’s main instrument, the Near Infrared Camera (NIRCam), for 2 hours at two different wavelengths. The team took this combined spectrum of quasar light and starlight for both galaxies, and then split the quasar light to see light from early stars in these galaxies for the first time.
Surprisingly, JWST observations of J2236+0032 and J2255+0251 and their galaxies have shown that the galactic mass/supermassive black hole ratio exists even in the early universe. These data alone are currently not enough to reveal the origins of this mass ratio and how supermassive black holes grow to such tremendous sizes, but they will inform future research.