Black holes are regions of spacetime where gravity is so intense that nothing, not even light, can escape. Comparing these immense entities to familiar celestial bodies, like our Sun, helps grasp their true dimensions. This article explores the colossal nature of TON 618, one of the most massive black holes known, by contrasting its size with our everyday star.
The Sun and TON 618: An Introduction
Our Sun, a G-type main-sequence star, anchors our solar system. It is a massive sphere of hot plasma, generating light and heat through nuclear fusion in its core, making it the primary energy source for Earth. The Sun represents a typical star in our galaxy.
In contrast, TON 618 is a hyperluminous quasar, a distant and exceptionally bright object powered by a supermassive black hole. Located approximately 10.8 billion light-years from Earth, its intense luminosity, shining with the power of 140 trillion Suns, originates from vast amounts of material spiraling into its central black hole.
Unveiling the Immense Scale of TON 618
The black hole at the heart of TON 618 is estimated to be approximately 66 billion times the mass of our Sun. This mass translates into an immense physical size, defined by its Schwarzschild radius, the boundary beyond which nothing can escape. For TON 618, this event horizon spans roughly 1,300 Astronomical Units (AU), or 2,600 AU in diameter. (One AU is the average distance between the Earth and the Sun.)
If placed at the center of our solar system, its event horizon would extend far beyond Neptune’s orbit, potentially encompassing the entire Kuiper Belt. TON 618 is about 32.5 times wider than our solar system and could swallow all its planets more than 40 times over.
How Astronomers Measure the Unfathomable
Black holes do not emit or reflect light, making them invisible to direct observation. Astronomers employ indirect methods to determine their mass and size. These techniques rely on observing the effects black holes have on their surroundings.
One significant method is reverberation mapping, which is particularly effective for active galactic nuclei (AGN) like TON 618. This technique measures the time delay between variations in the light emitted from the black hole’s accretion disk and the corresponding changes in the emission lines from gas orbiting further out in the broad-line region. By combining this time delay with measurements of the gas velocity, inferred from the Doppler broadening of emission lines, astronomers can calculate the size of the broad-line region and, consequently, the black hole’s mass. The characteristics of the swirling accretion disk also provide clues about the mass and spin of the black hole.
The Nature of Supermassive Black Holes
Supermassive black holes are the largest category of black holes, with masses ranging from millions to billions of times that of the Sun. These giants reside at the centers of most large galaxies, including our own Milky Way, which hosts Sagittarius A. Sagittarius A is considerably smaller than TON 618, with a mass of about 4.3 million solar masses.
Supermassive black holes play a role in the evolution of galaxies, with observations indicating a correlation between the black hole’s mass and the properties of its host galaxy. Their formation is thought to occur through various mechanisms, including the direct collapse of massive gas clouds in the early universe or the merging of smaller black holes. The rapid growth of some supermassive black holes, observed even in the early universe, continues to be an active area of research.