Luminosity and Size

The SDSS has data on many galaxies and quasars, over a wide representative range of distances, and in different environments. Some may be obviously in a cluster, some in a large wall, and others in or near a void. As you can see in the search for ``fingers'' artifacts may appear due to local effects. However, on a very large scale when $z$ is so high that the object is near the limit of visibility, local effects should be small compared to the cosmological expansion of the universe. At this limit, the luminosity and apparent angular size of a galaxy, or the luminosity of a quasar, might be indicators of distance determined from $z$.

In this open-ended question, use Partiview to select at least 20 objects of different type that lie over a wide representative range of distances, and in different environments. Use the on-line Sloan database to find apparent sizes and luminosities, and then look at how these are related to $z$. Document each galaxy and quasar you select. You may need to read about luminosity and angular distance scales, both of which are related to the comoving scale that is employed for the Partiview visualization.

1. Explore the apparent luminosity of a qso and its dependence on $z$ or $d$. Where are most qso's found? Are the faintest qso's at the greatest $z$? Is there a useful relationship that would enable a simple measurement of $m$ to lead to an estimate of $d$?

2. Study the dependence of the angular size and the total apparent luminosity of a galaxy on $z$ or $d$. Within clusters of galaxies, where are the biggest and brightest galaxies found? Is there a useful relationship that would enable simple measurements of angular size and total apparent magnitude to lead to an estimate of $d$?