PHYS366: Statistical Methods in Astrophysics

Before we start, let's see:

What is this course about, and how is it going to work?

Lesson 1: Exploring Data

Goals for this session:

• Familiarize ourselves with 3 types of astronomical data: images, object catalogs, and reported measurements
• Remember some summary statistics (and maybe learn some new ones) and put them into practice
• Build a generative model, and simulate some data with it

Related reading:

Ivezic Chapter 1, sections 1.1, 1.2, 1.4, 1.5, and Chapter 3, section 3.2.

What is "data"?

• Let's start thinking a bit about this.

Example 1: X-ray Image

Telescopes have cameras that record images.

• Let's take a look at an image from XMM

• Summary statistics give us a better picture of what is going on

Example 2: SDSS Catalog

Images get processed into automated detections and measurements of astronomical objects, which are then catalogued.

• First let's take a look at some SDSS galaxy measurements

• Summarizing galaxy positions: the "correlation function"

• Now let's look at the relationship between observed and intrinsic galaxy properties in more detail.

Example 3: Cepheid Measurements

Measurements of the properties of astronomical objects, and their error bars, are reported for further use.

• Let's look at some measurements of the properties of Cepheid stars

Recap

• What did we learn?