Question
Suppose that the typical galaxy has a mass of $10^{11} \mathrm{M}_{\odot}$. If the total mass of a cluster of 100 galaxies is $10^{15} M_{\odot}$, how much dark matter is contained in the cluster by the percentage of the total mass (ignoring the hot X-ray gas)?
Step 1
First, we need to find the total mass of the 100 galaxies. Since the typical galaxy has a mass of $10^{11} \mathrm{M}_{\odot}$, the total mass of 100 galaxies would be $100 \times 10^{11} \mathrm{M}_{\odot} = 10^{13} \mathrm{M}_{\odot}$. Show more…
Show all steps
Your feedback will help us improve your experience
Sunny Guha and 64 other educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Find the approximate mass of the dark and luminous matter in the Milky Way galaxy. Assume the luminous matter is due to approximately $10^{11}$ stars of average mass 1.5 times that of our Sun, and take the dark matter to be 10 times as massive as the luminous matter.
Assume that there are 1 trillion $\left(10^{12}\right)$ galaxies in the universe, that the average galaxy has a mass equivalent to 100 billion $\left(10^{11}\right)$ average stars, and that an average star has a mass of $2 \times 10^{30} \mathrm{kg}$ a. Ignoring dark matter, how much mass (in kilograms) does the universe contain? b. If the mass of an average particle of normal matter is $10^{-27} \mathrm{kg}$, how many particles are there in the entire universe?
Assume that the average galaxy contains $10^{11}$ Msun and that the average distance between galaxies is 10 million light-years. Calculate the average density of matter (mass per unit volume) in galaxies. What fraction is this of the critical density we calculated in the chapter?
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD