#4: Reading 2D Spectrographs

In my previous posts, I have mentioned that I will be using 2D spectra to find the uncorrected dark matter contents of galaxies. However, how exactly do I use 2D spectra to accomplish this? This post will explain the basics of how I collected data for my COSMOS project (which my senior project is based on), thus clarifying how exactly my initial data collection will work.

My data is in the form of a .fits file and is analyzed using the application DS9.

Below you can see how the application looks when initially opened:

As you can see, there are lots of different options available within this application. I do not know how to use all of them, and currently do not intend to do so unless necessary for my project.

Upon opening a .fits file and clicking a few functions I don't completely understand (I'm following instructions given to me by Professor Raja), this is the image I get:

Each distinct row represents a single astronomical object. (The specific details about this data will be saved for another blog post.) Now for a small amount of background information: spectra allow scientists to view the chemical composition of an object based on what light the object emits. Each of this emission lines refers to a specific chemical. Based on the patterns of these emission lines (the lengths between them), we can find certain patterns that correspond to specific groupings of chemicals. For example, the two circled sections contain two emission lines very close together. This relationship allows us to determine that both of these are O2 emission lines.

This is the first of several steps taken in analyzing 2D spectra to determine a galaxy's dark matter content. Over the next few days, I'll be posting more updates that explain the rest of my work with 2D spectra, how a spectrograph actually works, and details regarding the specific data I am working with.

Please leave any thoughts or comments below, and thank you very much for reading! Until next time, reader.

#technical #update