Active Galaxies and Black Holes
Active galaxies are galaxies that have unusually high levels of energy emissions in the form of radiation and very powerful jets of matter. They are typically powered by the supermassive black hole at their center. Supermassive black holes are the remnants of massive stars that have collapsed, eventually reaching a point of gravitational inflection and distorting space-time so drastically that nothing, not even light, can escape. Their strong gravity warps the space-time continuum and they often act as a sort of galaxy’s ‘nucleus’.
What Exactly are Active Galaxies and Black Holes?
Active galaxies are galaxies that produce significantly more light than expected. This increase in luminosity is caused by a supermassive black hole at its center, which is able to draw in and coalesce great quantities of matter. This matter can then release large amounts of energy as radiation as it is pulled toward the black hole, allowing an active galaxy to emit far more energy than a “normal” galaxy.
In contrast, a black hole is an area of space so dense that its gravitational pull is so immense that nothing, not even light, can escape from it. Its intense gravity warps and distorts the fabric of space-time in its vicinity, pulling in material from its surroundings and thus increasing its mass. A black hole can be observed as an area of bright emission, and as a result, is often referred to as a “quasar”.
The Difference between Active Galaxies and Starburst Galaxies
Active galaxies tend to be much larger than starburst galaxies. This is because they have much more material in their vicinity than starburst galaxies, allowing them to tap into a larger energy source. Additionally, active galaxies typically have much higher luminosity levels than a starburst galaxy as the supermassive black hole at its center emits large amounts of energy in the form of radiation.
On the other hand, starburst galaxies are compact and have much more star formation than an active galaxy. This is because they are actively accumulating material; either by gravitationally drawing in gas and dust from their surroundings or cannibalizing nearby galaxies that have passed too close. This allows them to create a flurry of stars, which can easily be identified by their bright colors.
The Relationship between Active Galaxies and Black Holes
Active galaxies and black holes are closely related, with the supermassive black hole at the center of an active galaxy having a powerful influence on what happens around it. Thanks to its incredible gravitational pull, the black hole is able to draw in and coalesce vast amounts of material and release large amounts of energy in the form of radiation, allowing the active galaxy to have significantly more luminosity than other galaxies. The supermassive black hole also creates powerful jets of material which can be seen shooting out from the center of the active galaxy.
Furthermore, black holes influence the evolution of an active galaxy by feeding material into the galaxy’s nucleus via accretion disks. This source of material allows for larger quantities of matter and gas to fuel the production of more stars, as well as new and more complex structures within the galaxy itself.
How Active Galaxies Form
Active galaxies are formed from the coalescence and accretion of matter and energy that is present in their vicinity. This is normally caused by a supermassive black hole at the center of the galaxy, which is able to draw in large quantities of gas and dust that are attracted to its immense gravitational pull. This process creates powerful jets of material that can be seen shooting out from the center of the active galaxy.
In addition, active galaxies may also form as a result of two smaller galaxies merging together, creating a much larger and more luminous galaxy as the two galaxies’ mass is coalesced into one.
The Discovery and Study of Active Galaxies
The first active galaxy to be discovered was Cygnus A, which was identified in the early 1950s. Following its discovery, there was an explosion of research into active galaxies, with the field becoming more and more developed as researchers sought to learn all that they could about the cosmic phenomena.
Using a variety of sophisticated teletools such as the Hubble Telescope and other large, sensitive radio telescopes, researchers have been able to study active galaxies in more detail than ever before and have made a number of amazing discoveries. The most notable of which being the identification of supermassive black holes at the center of many active galaxies.
Active galaxies and black holes are closely related and the supermassive black hole that lies at the center of an active galaxy has a powerful influence over the evolution of the entire galaxy. The black hole is able to draw in material, creating powerful jets of matter in the process, as well as fuel further star formation. Through the use of powerful teletools and cutting edge research, scientists have learned a great deal about active galaxies and black holes in recent decades and will no doubt continue to do so in the years to come.
