The power of active galactic nuclei was underestimated due to dust

Active galactic nuclei (AGNs) - supermassive black holes that absorb matter in the centers of galaxies - are one of the

most powerful energy sources in the Universe.They have long been known to outshine the combined light of billions of stars in their galaxies. In a new study, scientists show that their power is actually underestimated and they are even brighter.

Researchers at the University of California, Santa Cruz have shown that astrophysicists have previously underestimated the output power of AGNs because they didn't take into account how much their light is dimmed by dust.

In their work, the researchers studied NGC 5548 -it is one of the best studied active galaxies. It is located in the constellation Bootes at a distance of about 245 million light years from Earth. The analysis showed that the dust makes the active nucleus of the galaxy much redder and dimmer than it really is. This is reminiscent of how the Earth's atmosphere makes the Sun appear redder and dimmer at sunset.

Though the possibility that the dust clouds the lightfrom active galactic nuclei, has been recognized for a long time, its amount caused controversy and many considered it insignificant, the authors of the work say. In the study, the astrophysicists looked at seven different indicators of the amount of dust and found that they all agree well.

The results show that in ultravioletthe range where most of the energy is radiated, a typical active galactic nucleus releases an order of magnitude more energy than previously thought. At the same time, as the authors of the work note, the colors of NGC 5548 are typical for other active galactic nuclei, which means that the conclusions can be extended to other systems.

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