How Do We Know That Galaxy Clusters Contain a Lot

question 70

Multiple Choice

How do we know that galaxy clusters contain a lot of mass in the form of hot gas that fills spaces between individual galaxies?

• A)We detect this gas with X- ray telescopes.
• B)We infer its existence by observing its gravitational effects on the galaxy motions.
• C)The hot gas shows up as bright pink in visible- light photos of galaxy clusters.
• D)We can observe the frictional effects of the hot gas in slowing the speeds of galaxies in the clusters.

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Definitions:

Standard Error

A measure of the sampling distribution variability of a statistic, often used to describe the accuracy of a sample mean estimate.

Sample Median

A measure of central tendency that identifies the middle value in a sorted sample set.

Resamples

The action of drawing repeated samples from the same data set, typically used in bootstrap methods for statistical inference.

Bootstrap Confidence Interval

A bootstrap confidence interval is a type of confidence interval estimate calculated by resampling the original data with replacement, often used to estimate the uncertainty of a statistic.