Dr James Matthews

Astrophysicist

Hello!

I’m an astrophysicist working at the University of Cambridge. My research involves understanding two main topics: the origins of ultra-high energy cosmic rays and the physics of winds and jets from accreting systems. These two subjects are inextricably linked.

You can find more details on my research, outreach and publications below, read my PhD thesis or read my CV.

Information and movies from a recent paper can be found here here.

Our recent press release regarding the wind in J1357.2 can be found via the Royal Astrononomical Society, CNN or the University of Southampton.

Contact

matthews [at] ast [dot] cam [dot] ac [dot] uk

Institute of Astronomy
University of Cambridge, Madingley Road, Cambridge, CB3 0HA

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Projects

Cosmic Ray Acceleration

It is not yet understood where the highest energy cosmic rays originate. One of my main research goals is to figure out whether jets from AGN can accelerate the highest energy cosmic rays. More info here.

MHD turbulence and plasma

Turbulence is a crucial aspect of cosmic ray acceleration, as it allows scattering of the particles across a shock front. It turns out that cosmic rays can self-generate this turbulence via streaming instabilities, physics that is also important in feedback processes in clusters.

Disc Winds in Accreting Systems

Outflows are ubiquitous in accreting systems. I spent my PhD developing a Monte Carlo radiative transfer and photoionization code, and used it to synthesize spectra of accreting objects with associated outflows.

Quasar and AGN unification and orientation

It would be rather elegant if all accreting supermassive black holes could essentially be described by their mass, Eddington ratio and viewing angle. While countless other complications doubtless exist, I am very interested in testing this paradigm. Image credit: Shen & Ho 2014.

Public Engagement

My public engagement work has involved taking this huge inflatable planetarium into local schools, but also activities with the homeless in Oxford. I also enjoy giving public talks. These are often about alien life as that is the most popular topic for school children, but I've also given more specialised talks on winds and tori around black holes.

Selected Publications

Here are some of my favourite papers. You can find a full list of publications on ADS.

Hot, dense He II outflows during the 2017 outburst of the X-ray transient Swift J1357.2-0933 2019
Charles, P., Matthews, J. H., Buckley, D., Gandhi P.; Kotze, E.; Paice, J.
MNRAS Letters in press.

Cosmic ray acceleration by shocks: spectral steepening due to turbulent magnetic field amplification 2019
Bell, A., Matthews, J. H., Blundell, K.
MNRAS, 488, 2466.

Ultra-high energy cosmic rays from shocks in the lobes of radio galaxies 2019
Matthews, J. H., Bell, A., Blundell, K., Araudo, A.,
MNRAS, 482, 4303, arXiv:1810.12350

The origin of radio emission in broad absorption line quasars: Results from the LOFAR Two-metre Sky Survey 2018
Morabito, L., K., Matthews, J. H., P.N. Best, G. Gurkan, M. Jarvis, et al.
A&A, in press

Fornax A, Centaurus A other radio galaxies as sources of ultra-high energy cosmic rays 2018
Matthews, J. H., Bell. A., Blundell, K., Araudo, A.,
MNRAS Letters, 479, 76

Radiation-hydrodynamic simulations of thermally driven disc winds in X-ray binaries 2017
Higginbottom, N., Knigge, C., Long, K. S. Matthews, J. H., et al.,
MNRAS, 479, 3651

Cosmic Ray Acceleration by Relativistic Shocks: Limits and Estimates 2018
Bell. A., Araudo, A., Matthews, J. H., Blundell, K.
MNRAS, 473, 2364

Amplification of perpendicular and parallel magnetic fields by cosmic ray currents 2017
Matthews, J. H., Bell. A., Blundell, K., Araudo, A.
MNRAS, 469, 1849

Quasar emission lines as probes of orientation: implications for disc wind geometries and unification 2017
Matthews, J. H.; Knigge, C.; Long, K. S.
MNRAS, 467, 2571

The reverberation signatures of rotating disc winds in active galactic nuclei 2017
Mangham, S. W., Knigge, C., Matthews, J. H.; Long, K. S.; Sim, S. A.; Higginbottom, N.,
MNRAS, in press, DOI:10.1093/mnras/stx1863

Testing Quasar Unification: Radiative Transfer in Clumpy Winds 2016
Matthews, J. H.; Knigge, C.; Long, K. S.; Sim, S. A.; Higginbottom, N.. Mangham, S. W.
MNRAS, 458, 293

The impact of accretion disc winds on the optical spectra of cataclysmic variables 2015
Matthews, J. H.; Knigge, C.; Long, K. S.; Sim, S. A.; Higginbottom, N.
MNRAS, 450, 3.

Line-driven Disk Winds in Active Galactic Nuclei: The Critical Importance of Ionization and Radiative Transfer 2014
Higginbottom, N.; Proga, D.; Knigge, C.; Long, K. S.; Matthews, J. H.; Sim, S. A.
The Astrophysical Journal, 789, 1.

Talk Highlights

Invited Talk: Particle Acceleration in Jets July 2019
A Centenary of Jets, Jodrell Bank

Invited Review: Disc Winds in Accreting White Dwarfs July 2019
From Winds to Jets, Amsterdam

Invited Talk: UHECRs from Radio Galaxies December 2018
Hillas Symposium, Heidelberg

Invited Talk: UHECRs from Radio Galaxies November 2018
Particle Acceleration Conference, Calabria

Contributed Talk: UHECRs from Radio Galaxies November 2018
UHECR 2018, Paris

Invited Colloquia: UHECRs from Radio Galaxies 2017-2018
Belfast, Manchester, Nottingham, Oxford, Southampton

Testing Quasar Unification with Radiative Transfer Simulations June 2017
AGN Winds on the Georgia Coast, Jekyll Island, GA

Invited Review: Ultraviolet Astronomy March 2017
Broadband Astrophysical Processes, Southampton

Disc Winds Matter! Their impact on the optical spectra of cataclysmic variables September 2015
The Golden Age of Cataclysmic Variables, Palermo, Italy

Modelling the Spectra of Quasars: Clumpy Winds and X-ray Properties June 2015
The Extremes of Black Hole Accretion, Madrid, Spain

Modelling the Spectra of Quasars: Clumpy Winds and X-ray Properties June 2015
Black Hole Accretion and AGN Feedback, Shanghai, China

Public Talk- The Search For Alien Life 2015
Stargazing Live on campus event, University of Southampton

Modelling the Spectra of Quasars June 2014
Accretion Disc Winds Meeting, Durham, UK

The Impact of Disc winds on the optical spectra of Cataclysmic Variables 2012
Cataclysmic Variables Meeting, Columbia University, New York

Searching for Nearby Planets During Predicted Mesolensing Events 2012
Exoplanet Lunch, Harvard CfA, USA