Black holes are some of the most violent objects in the universe. They are created from the deaths of massive stars. When a star reaches the end of its life, it collapses under its gravity, causing a supernova explosion.

The star’s core keeps collapsing, getting heavier and denser until all that remains is a singularity, an infinitely small point of infinite density—a black hole.  

Black holes come in different types, depending on the star from which they were born.

1. Stellar black holes (SBHs) are born from the death of massive stars. Their masses ranges from 3 to 100 solar masses, i.e., the mass of the Sun (approximately 1.99 × 10³⁰ kilograms).
2. Intermediate black holes (IMBHs) are poorly understood. Their formation is thought to result from merging stellar black holes. Their masses range from 100 to 1000 solar masses.
3. Supermassive black holes (SMBHs) are present at the center of almost all galaxies. Their masses range from millions to billions of solar masses.

Let’s explore the seven largest black holes in the universe, which have various characteristics. This list is based on their mass (in terms of solar masses). 

Please note that all the masses are approximated.

1. Phoenix A

Mass: 100 billion solar masses

Location: Phoenix cluster

The Phoenix cluster is a massive galaxy of thousands of galaxies bound by gravity. This makes it one of the biggest galaxy clusters known to us.

At the center of this cluster lies Pheonix A, the central galaxy, which houses the active galactic nuclei (AGN). Supermassive black holes power AGN and play a crucial role in galaxy formation and evolution.

The SMBH at the center of Phoenix A is vital for the activity of the AGN. According to theoretical models, the SMBH has a mass of 100 billion solar masses. This means it could be the largest known black hole.

Its circumference is so large that it would take 71 days and 14 hours to go around it—if you were traveled at the speed of light!

The Schwarzschild diameter of its event horizon is approximately 590.5 billion kilometers, immense enough to dwarf our entire solar system. The Schwarzschild diameter is the theoretical boundary around a non-rotating black hole from which nothing can escape.

2. IC 1101

Mass: 40 to 100 billion solar masses

Location: Abell 2029 galaxy cluster

The IC 1101 is a lenticular galaxy. These galaxies fall between spiral and elliptical in terms of their shape. They have a disc structure similar to spiral galaxies but lack spiral arms. These galaxies have little ongoing star formation.

At the center of IC 1101 lies a black hole estimated to have a mass between 40 and 100 solar masses. The estimates are based on various theoretical models and related observational findings, which is why the variation is so large.

The black hole’s presence is inferred from the gravitational effects on neighboring gas.

3. TON 618

Mass: 40.7 billion solar masses

Location: Near Canes Venatici and Coma Berenices constellations

Quasars are a subclass of AGN. TON 618 is a superluminous quasar, i.e., exceptionally bright. They are pertinent to understanding galaxy formation and evolution.

At the center of TON 618 lies an SMBH of 40.7 billion solar masses. The mass of the SMBH is estimated from observational data of the quasar’s emission spectra, which is like the quasar’s thumbprint. 

It is also 140 trillion times more luminous than the Sun. Due to its luminosity, it provides crucial information about the behavior of the SMBH and its accretion disc, which is the rotating disk of gas and dust falling into it.

The TON 618 quasar also houses a large amount of neutral hydrogen, the most abundant element in the universe. It serves as the building block from which these structures are built. Therefore, it is of great interest to scientists.

4. S5 0014+81

Mass: 40 billion solar masses

Location: Near Cepheus constellation

The host galaxy is an FSRQ (flat spectrum radio quasar), a giant elliptical galaxy with extreme luminosity. Like TON 618, it also has an AGN and a SMBH at the center.

Due to its high luminosity, the SMBH’s mass has been estimated using the emission spectra of the host galaxy. It has 40 billion solar masses, equivalent to four large Magellanic clouds (the largest and most massive satellite galaxies orbiting the Milky Way).

The Schwarzschild diameter of the SMBH is 240 billion kilometers, half that of the SMBH in Phoenix A.

According to evolution models, the host galaxy formed in the early universe around 1.6 billion years after the Big Bang and will survive for another 1.3 x 10⁹⁹ years!

5. Abell 1201 BCG

Mass: 32.7 billion solar masses

Location: Abell 1201 galaxy cluster

Abell 1201 BCG, or brightest cluster galaxy, is the most luminous galaxy within the cluster near the center. The galaxy hosts an SMBH of 32.7 billion solar masses, according to a 2023 study.

Due to its massive size and gravitational influence, the black hole acts as a gravitational lens, bending the path of light from a more distant galaxy behind it.

This bending effect creates a visible distortion in the shape of the background galaxy’s image, which is used to estimate the SMBH’s mass.

Dark matter distribution also influences gravitational lensing. Therefore, this galaxy is an important candidate for studying the properties of dark matter.

6. NGC 4889

Mass: 21 billion solar masses

Location: Northern Coma Cluster

Located in the northern Coma Cluster, the host galaxy (NGC 4889) is a supergiant elliptical galaxy housing an SMBH. According to theoretical models, the SMBH’s mass is between 6 and 37 billion solar masses. The best-fit estimate is around 21 billion solar masses.

The SMBH is currently quiescent, not accreting matter and emitting radiation. This makes measuring its mass more difficult. However, due to its state, understanding how massive black holes evolve into active quasars is of interest.

Such massive black holes also affect the dynamics and evolution of the galaxy and its surroundings.

7. Messier 87

Mass: 6.5 billion solar masses

Location: Virgo constellation

Messier 87 or M87, like NGC 4889, is a supergiant elliptical galaxy located in the Virgo constellation. It hosts the only SMBH ever to be imaged at its center.

In 2019, its first-ever image was released using data collected by the Event Horizon Telescope (EHT). This same data was also used to estimate its mass of 6.5 billion solar masses.

The SMBH at the galactic center is the primary component of the AGN present in the galaxy. It is surrounded by a rotating disc of ionized gas, perpendicular to the relativistic jet, the narrow stream of plasma ejected near the center.

The relativistic jet itself extends over 5,000 light-years across. This is the distance from the Earth to the center of the Orion Molecular Cloud Complex, a nearby star-forming region.

The proximity of M87 and the clear view of the SMBH is vital for studying black hole dynamics and evolution. Moreover, the galaxy has an AGN, making it interesting to study galactic evolution.

The galaxy’s surrounding interstellar medium is enriched by elements from evolved stars. According to observational data, its outer structure is shaped by its interaction with neighboring galaxies.

Theoretical limit

One thing you may have noticed in this list is that apart from the SMBH in Phoenix A, all the black holes have masses of less than 100 billion solar masses, and there is a reason for this.

There is a theoretical upper limit to the mass a black hole can have based on radiation effects, which can slow down the growth of black holes and star formation in the accretion disc environment, which also regulates the growth of black holes.

According to theoretical models, the maximum limit is up to 270 billion solar masses, based on the age of the universe and the amount of matter in it.