Institute of Physics Juno Equality Diversity and Inclusion:
The main focus of my scientific research is the discovery and study of supermassive blackholes, galaxy formation and evolution, 1 billion years after the Big Bang (12 billion years ago which is 7 billion years before the Sun, Earth and Solar System formed) focusing on the discovery of high redshift quasars powered by the accretion of matter onto supermassive black holes, using ground and space-based, multi-wavelength (radio to X-ray) large sky surveys. I work on the discovery of quasars and active galaxies that host supermassive black holes, the determination of their space densities, star formation rates and how and when they are born and grow. I have also worked on the experimental determination of the rate of gravitational deceleration of the Universe. This work resulted in the unexpected discovery that the expansion of the Universe is accelerating and not decelerating as expected.
McMahon is the Principal Investigator (PI) of the ambitious VISTA Hemisphere Survey(VHS) which is a deep near Infra-Red sky survey project. The observational project has been awarded 300+ clear nights on the 4.2m ESO VISTA telescope in Chile. For a number of years, McMahon led the quasar science working group in the Dark Energy Survey(DES) project which built a very large CCD camera (DECAM) and was awarded over 500 nights on the US CTIO 4m telescope in Chile to use this camera to observe the sky at optical wavelength.
McMahon has been recognised for his contribution to the unexpected discovery the expansion of the Universer is accelerating (as a founding member of the Supernova Cosmology Project team) through the awards of the 2007 Gruber Cosmology Prize (2007) and the 2015 Breakthrough Prize in Fundamental Physics.
McMahon has over 25 years of experience in data intensive analysis and data intensive computational research in observational astronomy with leadership roles in national and international research projects, in ground-based and space-based data intensive multi-wavelength observational progammes from radio to X-ray wavelength involving the European Space Agency(ESA; XMM-Newton), European Southern Observatory (ESO; VISTA, 4MOST) and STFC (CASU, DES, LSST, IRIS, SKA, UKSRC). He was a founding member of the international Supernova Cosmology Project team that made the groundbreaking unexpected discovery that the expansion of Universe is accelerating and is a founding member of the international Dark Energy Survey collaboration. He has been a member of the UK DiRAC Project Board and PI of the DiRAC Data Intensive high performance computing service at the University of Cambridge since 2017. Since 2024, he has been the Co-Director of the national AI Research Resource (AIRR) Dawn project in Cambridge.
A common theme of his research is the development of data intensive multi-wavelength image analysis observational techniques that exploit technological developments to explore the boundaries of the observable and distant Universe. McMahon works closely with other researchers and engineers on emerging and cutting edge technology. They try to ensure that they minimise the use of unnecessary bleeding edge technology. McMahon makes progress by learning from his own mistakes and the mistakes and experience of both younger and older colleagues, who generously support him on his journey of discovery.
McMahon has a B.Sc. degree in Physics from Queen's University Belfast, a Postgraduate Certificate in Secondary School Education in Physics from the University of Cambridge and a PhD in Astronomy from the Institute of Astronomy, University of Cambridge. He held a Royal Society University Research Fellowship at the Institute of Astronomy from 1991 to 2000. He served as the Deputy Director of the Institute of Astronomy for four years from 2013 to 2017 and served as Director and Head of Department of the Institute of Astronomy for five years from 2017 to 2022.
- Who is the best connected scientist? A study of scientific coauthorship networks, Newman, Phys.Rev. E64 (2001) 016131; Phys.Rev. E64 (2001) [ Data ] "This analysis ranked McMahon as the 10th in the 'betweenness' category in Astronomy. See Table II on page 5";
