WRITTEN BY Phyllis ShEn

For a long time, black holes have been known to influence the development and growth of objects in the universe, including the formation of stars within galaxies (Somerville and Davé). Galaxies are clusters of stars held together by gravity, and the size of a galaxy is determined by the distribution of its stars. Dwarf galaxies are the most abundant type of galaxies in the universe, often orbiting larger galaxies and containing up to a few billion stars. For comparison, the Milky Way galaxy contains between 200-400 billion stars. In a recent recalculation of the mass of the Milky Way, scientists also observed that black holes within the center of galaxies influence the way globular clusters around the galaxies form and travel around the center of the galaxy (Science Daily). 

A supermassive black hole found at the center of a dwarf galaxy in 2014, as captured by the SINFONIA instrument from the European Southern Observatory’s Very Large Telescope in Chile. This was the smallest galaxy in which this type of black hole was known to exist, which opened the possibility of finding other supermassive black holes at the centers of other dwarf galaxies (Commissariat).

Black holes and dwarf planets both allow scientists to study the evolution patterns of galaxies. Researchers from the University of California, Riverside have used telescopes in Hawaii to observe winds around various black holes and have found that those black holes create winds that hinder the formation and development of stars, thus preventing the growth of small galaxies. These winds were observed to be stronger than the researchers had initially anticipated. This has a more drastic effect on the expansion of dwarf galaxies. The research done at the University focused on six dwarf galaxies, each with black holes that created gusts of wind at a high velocity containing ionized gas particles. These winds are created when particles in outer space come into contact with black holes. This contact generates high heat, due to friction and the strong gravitation of black holes. The heat causes massive amounts of energy to be generated to push gas particles out of the black hole. While wind produced by black holes can compress surrounding gas particles to form stars, the gas released from these black holes in dwarf galaxies does not compress surrounding particles because the gas itself comes from the black hole and is unable to form stars. Therefore, the presence and strength of the black holes within a galaxy are what determines the size of the galaxy by regulating the formation of stars. These discoveries may have further implications beyond the basic observation of star formations; they may potentially allow scientists to measure other properties of black holes and different-sized galaxies relative to their effects on each other (Access Science).

Commissariat, T. (2017, August 25). Gargantuan black hole found at the heart of dwarf galaxy. Retrieved from https://physicsworld.com/a/gargantuan-black-hole-found-at-the-heart-of-dwarf-galaxy/.

Access Science. (1970, January 1). New mass measurement for the Milky Way Galaxy. Retrieved from https://www.accessscience.com/content/new-mass-measurement-for-the-milky-way-galaxy/BR0321192. 

Science Daily. (2019, October 11). Black holes stunt growth of dwarf galaxies. Retrieved from https://www.sciencedaily.com/releases/2019/10/191011165322.htm.

Somerville, R. S., & Davé, R. (n.d.). Physical Models of Galaxy Formation in a Cosmological Framework. Retrieved from https://www.annualreviews.org/doi/pdf/10.1146/annurev-astro-082812-140951.