I grew up in the little fishing town of Kilkeel in County Down, at the foot of the Mourne Mountains.  I read Natural Sciences at Christ’s College, Cambridge and then did a Ph.D. in astrophysics at the Cavendish Laboratory. After postdoctoral positions as a Research Astronomer at the Royal Greenwich Observatory, and then as a PPARC Research Fellow back at the Cavendish, I came to Oxford as a departmental lecturer in physics in 2003.  I also held a college lectureship in physics at St Peter’s, and then I came to Exeter as a Tutorial Fellow in physics in 2015.

I am a member of a family that has been full of teachers for many generations, and I am very proud to have the opportunity to teach at a university like Oxford, and especially at a college like Exeter.

Astronomy is a discipline that involves a lot of travel, even by an academic’s standards, so it is fortunate that I have a love of flying and of travel in general.  When at home I am an enthusiastic (but certainly amateur) cook.


My research interests are centered on high-energy astrophysics, particularly in the relativistic jets and very-high-energy particles created in extreme environments such as accreting black holes and supernova blast waves.  I study these at all wavelengths from radio through to the highest-energy gamma rays.  My group works on both theory and experiment, with particular emphasis at present on the development of the next generation ground-based observatory for gamma-ray astronomy, the Cherenkov Telescope Array (CTA). We are currently spending much of our time perfecting the cameras for some 40 four-meter telescopes for CTA that will be constructed in the Atacama Desert in northern Chile over the next few years. We are quite a fun “Jack of all trades” group where on one flank we engage with the physics of black holes and relativistic particles, and on the other with applications of our experimental technology, in fields such as medical imaging. All of it is very exciting and the group is always eager to recruit new graduate students.


At Exeter I teach the first year papers Mechanics & Relativity and Electromagnetism; second year Thermal Physics and Electromagnetism, and third year General Relativity & Cosmology.

I lecture the courses Radiative Process in Astrophysics and High-Energy Astrophysics for the M.Phys. and M.Math.Phys. degrees of the Physics and Mathematics departments.

Selected Publications

Gamma-ray novae: rare or nearby? Morris, Paul J.; Cotter, Garret; Brown, Anthony M. Chadwick, Paula M., Monthly Notices of the Royal Astronomical Society, 465,1218, 2017

New constraints on the structure and dynamics of black hole jets Potter, William J.; Cotter, Garret, Monthly Notices of the Royal Astronomical Society, 453, 4070, 2015.

Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence Hallinan, G.; Littlefair, S. P.; Cotter, G. et al., Nature, 523,568, 2015. The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope, Abdo, A.A., et al., The Astrophysical Journal, 715,429, 2010.


Seeing across the galaxy

Media Coverage

For the first time ever, scientists spot an aurora outside our solar system, Washington Post

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