11: Black Holes

Last updated
Save as PDF

Page ID: 30488

Kim Coble, Kevin McLin, & Lynn Cominsky
San Francisco State University, Chico State University, & Sonoma State University

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Chapter 11 centers on black holes, including their properties and how we know they exist. Motivated by groundbreaking observations of our own Milky Way’s supermassive black hole, active galaxies, as well as solar mass black holes, you will examine the physical characteristics that result from the strong gravitational fields of these not-so-uncommon exotic objects. You will also engage in calculations of black hole sizes, temperatures, densities, and lifetimes.

11.0: Black Holes Introduction
In this chapter we hope to give you a more accurate picture of what black holes are and how they fit into the Cosmos.
11.1: What Are Black Holes?
You will understand that black holes are regions of spacetime from which light cannot escape. You will understand that the idea of black holes predates general relativity. You will understand how black hole mass and size are related.
11.2: Spacetime Near Black Holes
11.3: Quantum Effects Near Black Holes
An important aspect of black holes that lies outside the scope of general relativity is their quantum nature. General relativity is not a quantum theory of gravity, and so our understanding of how black holes will behave on extremely small scales is still far from complete.
11.4: Astrophysical Black Holes
Several decades ago advances in astronomical instruments opened new vistas on the Universe. Black holes popped out, sometimes glowing brightly in the darkness, other times remaining hidden except for their influence on visible neighbors. In this section we look at how black holes are detected and how they affect the Universe and its contents.
11.5: Wrapping It Up 11 - Black Hole Densities
Imagine a sphere around the black hole singularity reaching out to the Schwarzschild radius. This sphere represents the effective volume of the black hole. Yes, it's mass is seemingly concentrated in a point, but the sphere encompassing the region of no return is much larger. More massive black holes have larger Schwarzschild radii, so how does their average density compare to smaller examples?
11.6: Mission Report 11 - Black Hole Densities

The supermassive black hole at the core of supergiant elliptical galaxy Messier 87, with a mass about 7 billion times that of the Sun, as depicted in the first false-colour image in radio waves released by the Event Horizon Telescope (10 April 2019). Visible are the crescent-shaped emission ring and central shadow,[19] which are gravitationally magnified views of the black hole's photon ring and the photon capture zone of its event horizon. The crescent shape arises from the black hole's rotation and relativistic beaming; the shadow is about 2.6 times the diameter of the event horizon. (CC BY 4.0; Event Horizon Telescope)