The main focus of my scientific research is the study of galaxy formation and evolution, 1 billion years after the Big Bang (12 billion years ago which is 7 billion years before the solar system formed) focusing on the discovery of high redshift quasars powered by the accretion of matter onto supermassive black holes. 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 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 been awarded over 500 nights on the US CTIO 4m telescope in Chile to use this camera to observe the sky at optical wavelength.
DIRAC Bio statement: McMahon has over 25 years of experience in data intensive analysis and computational research, national and international project science, project management and data management in ground and space-based data intensive projects involving ESA (XMM-Newton), ESO (VISTA, 4MOST) and STFC (CASU, DES, LSST, IRIS, UKSRC). He has been a member of the DIRAC Project Board and PI of the DIRAC Cambridge Data Intensive service since 2017.
A common theme of his research is the development of data intensive observational techniques that exploit technological developments to explore the boundaries of the observable 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.