Saturday, March 6, 2021

TOM 618, The monster

TON 618 is a hyperluminous quasar 10.4 billion light years away from Earth, visible in the constellation Canes Venatici.

At the center of this quasar there is a black hole with a mass 66 billion times greater than that of the Sun, 15,000 times more massive than the black hole at the center of the Milky Way. For this reason, TON 618 has been classified as an ultramassive black hole.

TON 618 is the most massive single object discovered so far and the quasar that contains it is one of the brightest objects in the entire Universe. Its absolute magnitude is in fact -31, which is equivalent to saying that it is 140 trillion times brighter than the Sun.

TON 618 is also the largest black hole so far measured: the radius of its event horizon is in fact about 1300 AU, more than forty times the distance that separates Neptune from the Sun.

It is currently unclear how such massive black holes can form. The only known process that allows a black hole to reach such a high mass is by accretion. TON 618 is as mentioned at 10.4 billion light years from Earth: therefore it must have formed when the Universe was very young. However, it is believed that the time passed between the birth of the Universe and the formation of TON 618 was not long enough to allow the black hole to reach the observed mass only through accretion phenomena. Therefore, other currently unknown processes must have come into play that allowed it to grow so fast in a short time.

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