Stuff to do

• Learn about the ALFALFA survey and, especially, take a look at the Using ALFALFA for science page. What does ALFALFA detect? How can we use ALFALFA to learn about galaxies?

• Read about the Sloan Digital Sky Survey in order to answer these questions. Some useful links are given here:
  Main SDSS site         DR6 site        Imaging camera parameters and description
  
  a. What is the operational status of the SDSS?
  b. What are the central wavelengths of the filters used to produce SDSS images?
  c. Why is it useful to obtain images in 5 filters simultaneously?
  d. Over what portion of the galaxy is the spectrum obtained? Why might that be important?

• Make a web page for yourself to keep track of what you are doing; you should put it in the directory called /home/hatillo/katieh/spr08 (actually we will need to get you a computer account for this...). See my hints on how to get started.

• Get started with IDL
  See especially the Intro to IDL for ALFALFA page

• The Arecibo General Catalog (AGC) is our private database containing basic data on several hundred thousand galaxies. It is not intended to be used by or distributed to people outside the ALFALFA collaboration.
  1. What are the conditions of use?     Look here for the answer and follow the link to answer the next questions.
  2. What is the "UGC"?
  3. When is the AGC entry number equal to the UGC entry number?
  4. What is the "position angle"?
  5. What is the "TELCODE" for Arecibo+ALFA?
  6. Some galaxies have two velocity measurements: "VOPT" and "V21". In that case, what should you adopt as the recessional velocity for the galaxy?

• Reading ALFALFA catalogs:     ALFALFA produces catalogs containing a source name, the AGC number (where there is one), the HI centroid and the position of the optical counterpart, and then various parameters measured from the HI line.
  1. Learn what measurements are contained in an ALFALFA catalog.
  2. Write yourself a short IDL routine to read this test catalog, and try to calculate the HI mass from the parameter SintP

• Groups of Galaxies: Some galaxies are isolated, some are found in rich clusters, and the majority reside in groups. Groups themselves come in different varieties including "loose groups", "rich groups", "poor clusters", "compact groups", "fossil groups". For a science topic, it might be interesting for you to learn about groups of galaxies, how they are defined and indentified and how their properties are derived. Here are some references (this list will grow):
  • Giuricin et al. 2000, Astrophys. J. 543, 178 (NOG group catalog)     ADS link
  • Garcia, 1993, Astron. Astrophys. Suppl. 100, 47 (Lyon group catalog)     ADS link
  • Mulchaey, 2000, Annu. Rev. Astron. Astrophys. 38, 289 (X-ray properties of groups)
  • Hickson, 1997, Annu. Rev. Astron. Astrophys. 35, 357 (compact groups)
    Find papers yourself:   Link to the ADS abstract query form

  You might want to ask yourself some questions and start compiling their answers:
  • What distinguishes among the different kinds of groups (loose, compact, rich, etc)?
  • What are characteristic group properties (linear extent, number of galaxies, morphological mix, velocity dispersion, X-ray luminosity, X-ray temperature)?
  • What is the morphological appearance of a group in (a) optical light? (b) X-rays?
  • How can we estimate the total mass of a group?
  • How do groups compare to clusters in terms of the properties you mention above?
  • Tabulate comparative information on (a) the Local Group, (b) the Virgo cluster, (c) the Coma cluster. ( more later...)
  And, learn about the GEMS survey. (more coming here............)
  • catalog with links.

• SQL and the SDSS: Check out the EGG introductory notes running SDSS queries in SQL
  We want to be able to figure out how to identify galaxies that are group members. One way of course is to use the redshifts. But we should also be able to find potential/likely group members from looking at the photometric database; we need to set the search parameters to do that. There are two different problems to contemplate: (1) defining a magnitude-limited sample and (2) looking for low surface brightness objects that are potentially dwarf members of the group. Think about these issues. Then we can discuss....

• Training set of dwarf galaxies in Leo I: Here are links to the KK04 Leo dwarfs in the AGC. Think about ways to extract from the SDSS database the SDSS photometric (and where applicable, spectroscopic) objects and their basic parameters for these galaxies. The idea is to find common properties which distinguish the dwarf galaxies from other objects. My first suggestion is that you try to identify the dwarfs by looking at the stellar mass surface density: we would expect them to have a very low value of that property, so think about how to devise a measure of observables (we observe the optical apparent brightness and size, not the stellar mass surface density) which might work. For some notes on stellar mass, see: the ALFALFA for science page for some ideas; we may also look elsewhere for others (Bell et al. 2003,5 for example). We might use either PetroR50 or PetroR90 for the radius to get the surface area. Your first task will be to see what kinds of values you get for the dwarfs in the training set.