The Impact of Supermassive Black Holes on the Cosmic

May 16, 2023 6 mins to read

The Impact of Supermassive Black Holes on the Cosmic

Supermassive black holes (SMBHs) are among the most fascinating objects in the universe. These massive celestial bodies, with masses millions or even billions of times greater than that of the sun, are thought to exist at the centers of most galaxies, including our own Milky Way. While these objects may seem far removed from our everyday experience, their impact on the cosmic environment is profound and wide-ranging. In this article, we will explore the impact of supermassive black holes on the cosmic environment, from their formation and growth to their effects on cosmic structures, the cosmic microwave background radiation, and gravitational waves.

SMBH Formation and Growth

How they are formed:

Supermassive black holes are thought to form from the collapse of massive stars or the mergers of smaller black holes. As matter falls into a black hole, it heats up and emits energy in the form of radiation. This process, known as accretion, can release vast amounts of energy, which in turn can drive the growth of the black hole. SMBHs are thought to grow over time through a combination of accretion and mergers with other black holes. In fact, the growth of SMBHs is thought to be intimately linked to the evolution of galaxies, as we will discuss in the next section.

Factors that contribute to the growth of SMBHs:

The growth of supermassive black holes (SMBHs) is a complex process that is still not fully understood. However, there are two main factors that are thought to contribute to their growth: accretion and mergers. Here are some key points on these two factors:


  • Accretion is the process by which material, such as gas or dust, falls into a black hole due to its strong gravitational field.
  • SMBHs are thought to grow primarily through accretion of matter from their surrounding environment, such as from a nearby gas-rich galaxy or from the intergalactic medium.
  • The material that is accreted can form a rotating disk around the SMBH, known as an accretion disk, which can produce intense radiation across the electromagnetic spectrum.


  • Mergers occur when two or more galaxies, each with their own SMBHs, collide and merge together.
  • If the SMBHs at the centers of these galaxies are in close proximity, they can form a binary system and eventually merge through the emission of gravitational waves.
  • SMBH mergers are thought to play an important role in the growth of SMBHs, particularly at high redshifts (i.e., earlier times in the universe’s history).


SMBH Effects on Cosmic Structures

How SMBHs can affect their host galaxies and the surrounding cosmic structures?

SMBHs can have a significant impact on the structure and evolution of their host galaxies. For example, in galaxy mergers, the SMBHs at the centers of each galaxy can spiral toward one another and eventually merge, releasing vast amounts of energy in the form of gravitational waves. This process is thought to be a key driver of the growth of SMBHs, as well as the formation of galactic nuclei. SMBHs can also influence star formation in their host galaxies by heating and expelling gas from the galactic disk. This can result in the formation of a so-called “quasar mode” of star formation, which is characterized by bursts of intense star formation in the central regions of galaxies.

How SMBHs can influence star formation and the growth of galactic disks?

Supermassive black holes (SMBHs) can have a significant impact on the growth of galactic disks and star formation through a process known as feedback. Here are three key points on this topic:

  • Feedback refers to the process by which the energy and material released from an SMBH can influence the surrounding environment, such as a galaxy or its interstellar medium.
  • In the case of SMBHs, feedback can occur through two main mechanisms: radiation and outflows.
  • Radiation from the SMBH can ionize and heat gas in the galaxy, which can suppress or promote star formation depending on the strength and duration of the radiation. Outflows of material, such as gas or high-energy particles, can also affect the surrounding environment and influence the growth of the galactic disk and star formation.

SMBHs and the Cosmic Background Radiation

Impact of SMBHs on the cosmic microwave background radiation (CMB):

The cosmic microwave background radiation (CMB) is a faint afterglow of the Big Bang that permeates the universe. This radiation is thought to have been emitted when the universe was only 380,000 years old, and it carries important information about the early history of the cosmos. SMBHs can affect the CMB in several ways. For example, the energy released by accreting matter can heat up the gas in the intergalactic medium, which in turn can affect the properties of the CMB. SMBHs can also influence the CMB spectrum by producing non-thermal radiation, such as synchrotron radiation, which can mimic the CMB signal. The study of the impact of SMBHs on the CMB is an active area of research, with important implications for our understanding of the early universe.

How observations of the CMB can be used to study the properties of SMBHs:

  • The CMB can be used to study the large-scale structure of the universe, including the distribution of galaxies and galaxy clusters. These structures are thought to be influenced by the gravitational pull of dark matter and the effects of dark energy, which are both thought to be closely related to the presence of SMBHs in galaxies.
  • The CMB can also be used to study the properties of the early universe, such as its temperature and density fluctuations. These properties can provide clues about the formation and evolution of SMBHs, which are thought to have formed through the collapse of massive gas clouds in the early universe.

SMBHs and Gravitational Waves 

How mergers of SMBHs can produce gravitational waves?

Gravitational waves are ripples in the fabric of spacetime that are produced by the acceleration of massive objects. The detection of gravitational waves from the merger of two black holes in 2015 marked a major milestone in astronomy, and since then, several more gravitational wave events have been detected. SMBH mergers are thought to be among the most powerful sources of gravitational waves in the universe, and their detection can provide important insights into the properties of these objects. For example, the properties of the gravitational waves emitted by SMBH mergers can be used to infer the masses and spins of the black holes involved. The detection of gravitational waves from SMBH mergers is also important for testing theories of gravity and the nature of spacetime.


In conclusion, supermassive black holes are among the most intriguing and important objects in the universe. They play a significant role in the formation and evolution of galaxies, and their impact on the cosmic environment is far-reaching. From the growth of SMBHs through accretion and mergers to their effects on cosmic structures and the CMB, and the detection of gravitational waves, studying these massive objects is essential to understanding the universe we live in.

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