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School of Physical and Chemical Sciences

Astrophysics and Cosmology

Understanding the origin and evolution of stars and galaxies, the physics of neutron star extreme matter, and testing relativity through gravitational waves.

Cosmology studies our Universe on the very largest scales: characterising how large groups of distant galaxies are arranged and explaining how these structures were generated by the Big Bang. Light from these galaxies, as well as the Comic Microwave Background light from the early Universe, has allowed cosmologists to build a coherent narrative of how our Universe has evolved into the night sky we see today. But light has its limitations. Some cosmic ingredients, like dark matter and dark energy, do not emit light and interact only through gravity. There is also a limit on how far away (how far back in time) we can ever see with light: about 380 000 years after the Big Bang, when the CMB was formed. Before this time, the Universe is so hot and dense that it is effectively opaque to light.

Gravitational waves offer an exciting new window into how the Universe evolves and what it is made of. Rather than measuring the light given off by distant galaxies, we can now measure the gravitational waves they emit. This allows us to detect dark objects such as black holes (that do not emit light) and could therefore help uncover the nature of dark matter and dark energy. Gravitational waves can also be used to look back much further in time (since they interact weakly with matter, the early Universe is effectively transparent for gravitational waves). 

Just as Galileo's telescope expanded our view of the cosmos - revealing new and surprising features about our solar system - gravitational waves are now expanding our experimental reach in what will surely be new and surprising directions. 

Cosmic events in the very early Universe, such as inflation and the formation of primordial black holes, can produce characteristic gravitational wave signals. 

 

Key questions

  • How to combine gravitational wave and cosmological constraints to test gravity on very different scales?
  • How can we determine cosmological parameters using the gravitational waves from distant binaries?
  • What could a primordial component to the stochastic gravitational wave background tell us about the early Universe?
  • What are the possible gravitational waves or primordial black hole abundances that can be produced during inflation or reheating?
  • How to use gravitational waves as a new probe of large-scale structure (e.g. as novel tracers of luminosity distance)?

 

Relevant Members

GWI members working on astrophysics and cosmology include:

  • Bernard Carr
  • Anson Chen
  • Chris Clarkson
  • Tim Clifton 
  • Katy Clough 
  • Charles Dalang
  • Matt Davies 
  • Charalamos Markakis
  • Scott Melville 
  • David Mulryne 
  • Raphael Picard
  • Oliver Pitt
  • Alexander Polnarev
  • Hong Qi
  • David Waisman Andrade
  • Stefano Zazzera

(See Our Members for contact links)

 

Events and Outreach

 

Recent Publications

  • The clustering of dark siren host galaxies, 
    C. Dalang, T. Baker [arXiv:2310.08991]
  • Magnification and evolution bias of transient sources: GWs and SNIa, 
    S. Zazzera, J. Fonseca, T. Baker, C. Clarkson [arXiv:2309.04391]
  • Testing the nature of gravitational wave propagation using dark sirens and galaxy catalogues,
    A. Chen, R. Gray, T. Baker [arXiv:2309.03833] 
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