UAT 2019 Workshop Preparation: Teleceon 2

Arecibo Observatory

Preparation for UAT 2019 Workshop: Planning Telecon 2

Purpose: Scientific Background

At the Green Bank workshop, we will learn about radio observations of different types of galaxies to establish their physical properties. The Undergraduate ALFALFA Team is working together on several related projects, including the Arecibo Pisces Perseus Supercluster Survey (APPSS) using observations at Arecibo Observatory, and a study of very low surface brightness galaxies, using observations at Green Bank Observatory. In these projects, we target faint galaxies of unknown distance that may be low mass and gas-rich. Detections will tell us their gas mass and their distance, allowing us to understand better the number, distribution, and dark matter content of low mass galaxies. This telecon will discuss background on galaxies, radio observations, and surveys such as ALFALFA and the Sloan Digital Sky Survey.

Background Reading

Review the Introduction to Arecibo Observing
Review the ALFALFA summary of 21-cm radiation, describing the 3 things the 21-cm spectrum tells you about a galaxy. Also review Hubble's Law.
Read about the ALFALFA survey.
Learn about the SDSS survey including a Video Introduction to the SDSS
Galaxy links in the Things to Know page and the SDSS Galaxy Tutorial .
Review the Large Scale Structure of the Universe

Questions

How are galaxies classified? What is the Hubble Tuning Fork?
What is meant by large scale structure? How does large scale structure affect the motion of a galaxy?
ALFALFA and SDSS are known as "blind surveys". What does this mean? Why are blind surveys useful?
Describe briefly the Sloan Digital Sky Survey (SDSS). What kinds of observations are available through the SDSS?
Describe briefly the ALFALFA survey. What measurements can we make of galaxies detected by ALFALFA?
Should we expect to detect all galaxies in both SDSS and ALFALFA? Why or why not? What kinds of galaxies would each survey be most sensitive to?
Let's say we find a galaxy in the Sloan Digital Sky Survey that seems to be blue and star-forming, but it wasn't detected by ALFALFA. Should we assume the galaxy has no HI gas? What is a more likely explanation?
Our current projects are targeted, meaning that we pick specific galaxies to observe. Why do we do this instead of carrying out another blind survey?
We observe "line-emission" in our studies. What other types of radio emission exist and what types of objects can be detected?
Many sources are blackbody or thermal sources. What is the characteristic shape of the spectrum of a thermal/blackbody source? What is the best blackbody known? What thermal sources do galaxies contain and at what wavelength(s) can we best study them?

Answers will be discussed in the Second Green Bank Workshop Preparation Telecon

Last modified: Mon Jun 3 15:16:53 EDT 2019 by becky