“Finding black-holes in a chirp” How to understand the first gravitational-wave detection

Link to the demonstrator: in English 


Age: >17

Duration: 3 hours

Equipment: PC with internet connection

Contact details

Author: Dr. Matteo Barsuglia (PCCP)

Contact: info[at]frontiers-project[dot]eu



This demonstrator introduces the concept of gravitational waves, their possible sources, and the way they have been detected. Students are introduced to the basics of data analysis using the real signal of the first gravitational wave ever detected, produced by the motion of two inspiralling masses. Real images from the sites of the LIGO and Virgo instruments will be used to explain the process of gravitational-wave detection. Students will learn how to determine the masses and the radius of the binary system, to identify the two objects as black holes, and what are the fundamental properties and parameters of a black hole. The demonstrator offers the choice between carrying out the analysis in an analytical way or on the real ASCII data files using python scripts. Students can present their work to the class and discuss how they compare with the most accurate results that astronomers have.


Learning outcomes:

  1. Teach students the basics of general relativity, black holes, and gravitational-wave emission and detection.
  2. Allow students to understand the methodology and reproduce the analyses behind the discovery of gravitational waves.
  3. Introduce basic concepts of astrophysics and gravitational-wave astronomy.


Prior knowledge:

  • Algebra
  • Basic concept of calculus
  • Wave properties
  • Knowledge of Newton and Kepler laws


Concepts introduced:

  • Basics of general relativity
  • Gravitational-wave emission
  • Binary black holes systems
  • Schwarzschild radius 
  • Chirp mass



Learning intentions:

By the end of this demonstrator, students should be able to:

  • Define a gravitational wave and interpret its signal
  • Explain the gravitational waves observation method
  • Calculate the Schwarzschild radius of an astrophysical object.
  • Explain the merger of a binary system and draw a scheme of the gravitational signal emitted.


Key activities:

  1. Videos to engage
  2. Data analysis and explanation
  3. Optional: python scripts for data analysis
  4. Final report and discussion




By the end of this demonstrator, students should be able to answer the following:


  1. Write a couple of sentences describing what you’ve learned about the properties of gravitational waves (what they are, why we want to find and measure them, etc.).
  2. The difficulty of the measurement (10-18m) is enormous. Can you describe how to detect gravitational waves using the working principles of interferometers?
  3. What is a black hole and which parameters characterize it?
  4. Which source parameters can we get from the analyses of the gravitational-wave signal?
  5. How do we know what the chirp mass of a binary system is?

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