Searching for and Identifying Pulsars

The manual Searching for and Identifying Pulsars was written by Ryan Lynch, a young pulsar astronomer. He wrote the manuscript just for high school students entering into the PSC. This document is written for a high school reading level and contains a glossary at the end. There are useful diagrams in the manuscript to help you visualize concepts.

I have developed this worksheet to help you capture the important parts of the manuscript that will help you understand pulsars and the data you will be analyzing. Some of the questions may require additional research to answer. Please use internet (or other) resources for increase your understanding of the question and to develop your response. Note: if you use resources other than the manuscript you must cite your sources.
Directions: In groups of 3

  1. Use the space provided to brainstorm ideas and jot them down.
  2. You (each person) are to write a well-constructed response to each of the following questions. Construct your response by developing a statement that introduces the question. These responses are to be electronically constructed on this page below each question. Color your response in blue.

Introduction

  1. Describe the matter that makes up a pulsar (and all neutron stars). Be certain to include information about composition and density. Write a statement about what makes this matter so unique?
  2. Pulsars (and all neutron stars) have very strong gravitational fields. Why is a neutron star so small in diameter? Most neutron stars have a mass of about 1.5Msun, what would happen if this mass were to increase to about 2 or 3 times the mass of our Sun and why?
  3. Pulsars have extreme magnetic fields. Discuss the magnetic fields of neutron stars and how the magnetic field is responsible for us (on Earth) observing pulsars. (In this response you should discuss the spin of a pulsar and state why all pulsars are neutron stars but not all neutron stars).
  4. Describe what is meant by “Pulsars are very precise clocks”. In this response you should define clock, discuss the period of a pulsar and its stability.

Finding Pulsars

  1. Why do astronomers have to “fold” the data recorded by a radio telescope when searching for pulsars?
  2. What does the Fourier transform do to the radio signals it collects? Discuss what the transform does and why it needs to be done to observe signals from pulsars.

Radio Frequency Interference

  1. What is RFI and why do astronomers have to worry about it? Include in your response examples of RFI (manmade and natural) why you are analyzing this data and not a computer.

PRESTO and Finding Pulsars (Note: Prepfold, PRESTO and FFT plots are all the same thing)

  1. Describe the information in the time domain and pulse profile and how they are related.
  2. Describe what you expect to see in the time domain and pulse profile subplots of a real pulsar.
  3. What is the difference in spin frequency and observing frequency? Define both.
  4. The DM graph is a graph that tells us nothing about the pulsar itself. Describe the variables on this graph and discuss how to analyze this graph and the implications of the information on this graph.
  5. Define the period and P-dot and explain how they are related. Then describe what the P-dot tell us about the pulsar.

Pulsar AstronomyPage 1