Table of contents
The present text will explore the properties and characteristics of black holes in our universe, formulated through studies and evidences concluded by researchers. This research will likewise investigate topics of Primordial Black Holes and the existence of a Super Massive Black Hole within a Large Magellanic Cloud.
The universe is comprised of many unknown and breath-taking things. Feasibly, for decades black holes have been in the forefront of discussion when conversations of space exploration are taught. When we think of black holes, we instinctively think of a timeless vacuum that consumes any object close enough to it’s radius. In many instances, this is true, very true.
The Belly of The Beast
Black holes are highly concentrated entities in our very vast universe, where gravitational fields in this region is so powerful, that it prevents matter or radiation from fleeing the void1. Not only can it hold physical objects, it is even strong enough to hold light from escaping. Essentially, the core gravitational pull within the black hole is able to slow down the speed of light to the point where it loses energy. In a broader sense, a black hole is fundamentally a one-way trip to the point of no return.
Straight forwardly, the heavier the star is, the brighter and more fuel it consumes. Once the star expends all of its fuel, the process of nuclear fusion is unable to offset the gravitational forces, resulting in the star collapsing in on themselves, creating a black hole. The size of the star does not necessarily need to be the largest of stars, rather they have to be dense enough to form black holes. Moreover, they would relatively need to be 20 times the mass of our sun in order to become a black hole. To set a general understanding of this, any star that lays on the main-sequence less than or equal to the mass of the sun cannot perform this process, as they will live out the rest of their lives until it becomes a white dwarf star.
Effectively, there are four different classes of black holes. There are the supermassive black holes, intermediate black hole, stellar-mass black holes and micro black holes, all to be blackholes discernible by astrologists. These classifications are determined by their behaviour; spin, electric charge, and mass.
- Supermassive black holes: figuratively the largest class of black holes are found in the ranges of millions to billions of solar masses; can be found in the center of galaxies.
- Intermediate black holes: this class of black holes is more-less a theory, as it has little evidence of its existence. It was theorized to have a mass of a hundred or to even thousands of times larger than our sun.
- Stellar-mass black holes: this classification of black hole is significantly smaller than the supermassive and intermediate black holes, but rather only a few times larger than the sun’s mass.
- Micro black holes: similar to the intermediate black hole, this black hole is also theoretical. This type of black hole is theorized to have been formed after the creation of our universe. Though it is named micro black hole, they would come in a variety of different sizes, from micro to supermassive.
The concept of black holes can be dated back to 1915, where Albert Einstein’s theory of general relativity was able predict the behavior of the black holes we know today. Now it may seem hard to believe that they are visible to astronomers since it is the “black hole”, which is true, but there are ways to detect this entity. As we know, black holes produce mass amounts of gravitational force around its horizon, although we cannot see it, we can observe the movements of nearby stars with inferred technology. In retrospect, since the black hole produces a large gravitational pull, stars neighbouring the black hole will be orbiting around it. Essentially, the stars would be orbiting nothing since the physical hole is not visible. Another key giveaway is the observing the radiation of nearby material being pulled towards the galactic centre. As speed varies within the brim of the black hole, material orbiting the horizon like dust and gas are forced into emitting radiation by the nature of friction, where telescopes can then detect the movement and signatures. Also, by consuming nearby dust and gases, black holes are able to conceal themselves, virtually being undetected visually.
Primordial Black Holes and The Large Magellanic Cloud
Astronomers theorized that the existence of black holes have been around since the early life of the universe. As stated before, micro black holes, further known as primordial black holes, are ancient black holes theorized to have been created shortly after the big bang3. Astronomers are able to conclude these theories by identifying the density of space in certain regions. When black holes reach the end of their life span, they would produce an empty void in the space they occupied. Therefore, by looking at the clutter in certain regions of the universe, determining the fluctuation of more or less dense regions, we can strongly suggest that a black hole existed at that point in time6.
“Can the universe contain sub-stellar-mass black holes, and what would their properties be?” First, we need to understand that sub-stellar-mass means to have less mass than a star. With masses lower than our sun for say, would be unable to become a black hole, but rather a white dwarf due to its small size. In this case, the property of a star needs to be three times greater than the mass of the sun to collapse into a black hole, we can conclude that it is not possible to for a sub-stellar-mass black hole to be formed. But judging the probability of it being true, it is highly unlikely for a star to create a sub-stellar-mass black hole, rather they would have to exist in the era of primordial black holes. These tiny black holes could possibly exist in the early stages of the universe the area of space was denser back then, allowing smaller stars to gravitationally collapse within itself, hitting critical mass. “Does the Large Magellanic Cloud (LMC) contain a Super Massive Black Hole?”
LMC short for large magellanic cloud is a nearby satellite galaxy to our Milky Way, about 70 million light-years away from Earth7. This dwarf galaxy is around 10 billion solar masses compared to our Milky Way’s 1 trillion solar masses. Judging by this ratio, it is hard to say that a supermassive black hole would be inside the LMC, but there is. Recently, astronomers announced that they have found a supermassive black hole in our neighboring dwarf galaxy. This supermassive is estimated to be around three-fourths of our Milky Way’s supermassive black hole, Sagittarius A7. This black hole in the LMC equates to 4 percent of the galaxy’s total mass, whereas other supermassive black holes weigh less than 1 percent relative to the galaxy’s mass. This could possibly raise a potential problem as the black hole may tear the system apart.
The formation of black holes is much more complex than it being spawned through the big bang. It is a chaotic and dynamic process on how they are formed, but through the research and evidence of this report, the properties and characteristic of black holes within our universe is an astounding process. The theoretical existence of a primordial black holes and the existence of a supermassive black hole within a Large Magellanic Cloud, further implicates our understanding of how the universe works.
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- NewScientist. Introduction: Black Holes. https://www.newscientist.com/article/dn18348-introduction-black-holes/ (Accessed 12 March 2019)
- HUBBLESITE. Do All Stars Become Black Holes? http://hubblesite.org/reference_desk/faq/answer.php.id=57&cat=exotic (Accessed 12 March 2019)
- Sky&Telescope. Sizes of Black Holes: How Big is a Black Hole? https://www.skyandtelescope.com/astronomy-resources/how-big-is-a-black-hole/ Accessed 12 March 2019)
- LIGO. A Search For Sub-Solar Mass Black Holes. https://www.ligo.org/science/Publication-O1SSM/index.php (Accessed 12 March 2019)
- NewScientist. Science: Astronomers gain insight into black hole accretion. https://www.newscientist.com/article/mg12516982-000-science-astronomers-gain-insight-into-black-hole-accretion/ (Accessed 12 March 2019)
- Astronomy. This teeny, tiny galaxy is hiding a supermassive black hole. http://www.astronomy.com/news/2018/08/teeny-tiny-galaxy-with-a-supermassive-black-hole (Accessed 12 March 2019)
- K.Blundell, Black Holes: A Very Short Introduction (Oxford University Press, Oxford, 2015), p.6
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