James Allison

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James Allison

CDF Christ Church

I am a Career Development Fellow in Astrophysics at Christ Church. I am a radio astronomer with a passion for data analysis and statistical techniques. My main research interests lie in galaxy evolution, the interstellar medium, radio-loud active galactic nuclei and cosmology.

I am a Physics undergraduate tutor at Christ Church and a member of the University of Oxford Physics faculty. In 2019/2020 I will be giving Physics tutorials in 1st year Mathematics and 3rd year General Relativity and Cosmology.

Overview

I study galaxies in the distant Universe in order to understand how they evolve over cosmic history. My current research focuses on how changes in the neutral gas content of galaxies drive the rate at which stars form and supermassive black holes grow. I specialise in using state-of-the-art numerical and statistical methods to detect and model the faint 21-cm line radio signature of neutral hydrogen gas more than 10 billion light years away. By understanding the physical processes that drive the growth and life-cycle of galaxies we can understand how our own Galaxy came to be and where it may lead in the future.

I use the most advanced radio telescopes in the world to carry out my research. These include the Australian Square Kilometre Array Pathfinder (ASKAP), an array of 36 antennas fitted with phased array feed technology that increases the field of view by a factor of 30, and the super-powerful MeerKAT array in South Africa. These new radio telescopes allow us to survey the Universe faster and deeper than previously achievable. They are sited in some of the most remote locations on Earth to provide a radio quiet environment that is free of interfering signals. I am co-Principal Investigator of the ASKAP First Large Absorption Survey in HI (FLASH) that will measure the neutral gas in galaxies up to 10 billion light years away.

Publications

My research is published in several of the major astronomical and general science journals. An up-to-date collection can be found at the following Google Scholar and NASA ADS libraries.

FLASH

I am a principal investigator of the First Large Absorption Survey in HI (FLASH), a major survey for neutral hydrogen in the distant Universe using the Australian Square Kilometre Array Pathfinder (ASKAP). Atomic hydrogen (HI) is a major component of the neutral interstellar medium in galaxies and is a vital ingredient in the processes that lead to the formation of stars and growth of supermassive black holes. FLASH will survey the entire southern sky between 700 and 1000 MHz, at a spectral resolution of 18.5 kHz (6.4 km/s), in order to search for HI 21-cm line absorption towards approximately 150,000 radio sources. The expected data rate in terms of useful raw products (visibilities) is approximately 12 TB per hour, or 20 PB over the entire survey. A total of 55 TB of image data will be generated by the processing pipeline. The principal science aims are to:

  • Determine the evolution of neutral hydrogen in the Universe over the past 8 billion years of cosmic history
  • Study how the HI content of galaxies in the distant Universe is affected by physical conditions and environment
  • Detect neutral gas in the central regions of the most powerful radio-loud active galactic nuclei and study mechanisms for fuelling and feedback in their host galaxies

Throughout ASKAP commissioning the FLASH survey science team have been carrying out pilot science projects to demonstrate feasibility. Several of these results have been published and can be found at this NASA ADS library.

Software

I have a passion for using advanced statistical techniques in my research and have published some of my analysis software on GitHub.