AST black hole

Black Holes Overview

Objectives:

After completing the Black Holes lab activities, you will be able to:

Identify and discuss the following characteristics of black holes:

· Three types: primordial, stellar, and supermassive

· Discuss what it means to overcome electron and neutron degeneracy

· Identify the importance of the event horizon and the photon sphere

· Gain a fundamental understanding of the exit cone

Black Holes Background

Black holes are the densest form of matter known. They are neither black nor a hole, but observations of them look like a black hole. This is because all particles, even light, are trapped inside their event horizon by an excessively strong gravitational field. This means that no signal can be bounced off of them, and no direct observation of them can be made.

Image credit NASA and ALMA.

There are three types of black holes, distinguished by the time and circumstance of their formation. The first is a primordial black hole. These formed very soon after the Big Bang before the Universe had time to expand significantly. While no primordial black holes have ever been confirmed, they should theoretically exist.

The second is a stellar black hole. This is one possible remnant from a supernova, the explosion at the end of a high mass star's life. The third is a supermassive black hole. These are located at the center of galaxies and are created during the QUASAR phase. The following three URLs address these black hole varieties.

http://www.astronomy.com/news/2018/02/the-search-for-primordial-black-holes-continues (Links to an external site.)

https://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-black-hole-k4.html (Links to an external site.)

http://hubblesite.org/reference_desk/faq/answer.php.id=62&cat=exotic (Links to an external site.)

 

There are three characteristics of black holes that are important to consider for this lab. The first is the event horizon. This is the distance from the black hole where the escape speed is equal to the speed of light. In order to get away from the black hole from this distance, you must travel directly away from the black hole at the speed of light.

The second is the photon sphere. This is the distance from the black hole where the orbital velocity is equal to the speed of light. Photons can be trapped in a circular orbit at this distance.

The third is the exit cone. This is a bit more subtle, and describes the collection of directions at which escape from the black hole's gravitational field is possible. The following two links address these topics.

https://www.skyandtelescope.com/astronomy-resources/whats-inside-a-black-hole/ (Links to an external site.)

https://www.usatoday.com/story/news/2018/06/15/supermassive-black-hole-eats-star-and-researchers-watch/704374002/ (Links to an external site.)

 

Finally, knowledge of electron and neutron degeneracy is needed for some of the work in this lab. http://www.sun.org/encyclopedia/degeneracy