Review Questions

1. Briefly outline some of the several considerations that one must balance if they are to design a survey that can achieve their target science goals. 

2. Briefly outline some of the several considerations that one must balance given the observational limits and current availability of astronomical facilities capable of carrying out the survey as designed.  

3. For a given survey, what is the "absorber survey space"?  What measured quantities are used to quantify the absorber space?

4. What constitutes the "fundamental attributes" of a survey (consider Figure 31.5)? Why is it important to define these attributes and to clearly communicate them when you publish your work?

5. In your own words describe (i) the total redshift path of the survey, (ii) the redshift sensitivity path of the survey, and (iii) the absorber redshift sensitivity array of the survey. 

6. What is the conversion from redshift paths to co-moving redshift paths for the quantities mentioned in Problem 5?  

7. There are at least two ways to compute the absorber redshift sensitivity array of the survey. Compare and contrast the "dichotomic detection threshold array" and the "completeness weighted sensitivity array". What are the advantages and disadvantages of either (or both)?

8. Describe what an "absorber subspace" is and how defining these subspaces is a tool for exploring and quantifying evolution in absorbers of various properties. Give at least two examples of absorber subspaces.

9. In large surveys, automated finding algorithms are required. In the context of such algorithms, what is "response bias" and what are some source of response bias? One form of response bias is a "false positive" detection. What are false positives?  

10. Explain the difference between the "observed counts" in an absorber subspace and the "cosmically true" (or "real") number of absorbers in that absorber subspace.  Describe the main steps, both automated and human, that are undertaken so that the cosmically true counts can be estimated from the observed counts.

11. Consider Equation 31.28, which provides the final estimate for the cosmically true number of absorbers in a survey subspace.  Qualitatively explain this equation: (i) describe what the numerator quantities/corrections are from left to right, (ii) describe the denominator quantities/corrections, (iii) describe how the ratio provides the estimated cosmically true number.

12. Though a great deal of formalism has been developed in this chapter, the methods of applying the correction can be highly simplified, modeled, and parameterized using Monte Carlo simulations. Consider Figures 31.10 and 31.11 and describe how these results can be applied to implement the corrections required to estimate the cosmically true absorber counts in an absorber subspace.

Problems

1. Under construction