Arvind (Neuqua Valley High School)

Quasars are the brightest and some of the most powerful objects in universe, yet we know so little about them. Many theories state that quasars lie in the center of galaxies and are powered by supermassive black holes. The problem is that this is all theory. Since quasars are so distant, it very difficult to observe their intrinsic properties. For example, the average mass of quasars has not been accurately measured.

Using weak gravitational lensing, Arvind and Dr. David Johnston attempted to measure the average mass of all quasars. In order to do so, they used quasars as the lensing objects and the galaxies behind those quasars as the background objects. This enables them to measure the average shear, or the amount of light that bends from the background galaxies, around the quasars. The question is: is this even possible?

Since quasars are so distant, it has been thought that there are very few galaxies behind quasars. And if there are, then the signal/noise ratio of the measurements would be too low for any proper research. So, with that being said, Arvind and Dr. Johnston worked together to determine a high signal/noise ratio. They discovered that it is possible to use quasars as the lensing objects. This means that weak gravitational lensing can be used to determine the average mass of all quasars.

In order to carry out the research, Arvind needed to program in IDL to analyze the data collected from the SDSS. With IDL, Arvind made many programs that plotted the distribution of quasars and galaxies, the number of galaxy/quasar pairs, and the signal/noise ratio in the area. This information leads to the significant conclusion that the average mass of quasars can be measured using weak gravitational lensing.

You can find Arvind's PowerPoint presentation as well as a few of the IDL scripts from his project below.