The DiRAC-2.5y Facility

Lead Research Organisation: University of Leicester
Department Name: Physics and Astronomy

Abstract

Physicists across the astronomy, nuclear and particle physics communities are focussed
on understanding how the Universe works at a very fundamental level. The distance scales
with which they work vary by 50 orders of magnitude from the smallest distances probed
by experiments at the Large Hadron Collider, deep within the atomic
nucleus, to the largest scale galaxy clusters discovered out in space. The Science challenges,
however, are linked through questions such as: How did the Universe begin and how is it evolving?
and What are the fundamental constituents and fabric of the Universe and how do they interact?

Progress requires new astronomical observations and experimental data but also
new theoretical insights. Theoretical understanding comes increasingly from large-scale
computations that allow us to confront the consequences of our theories very accurately
with the data or allow us to interrogate the data in detail to extract information that has
impact on our theories. These computations test the fastest computers that we have and
push the boundaries of technology in this sector. They also provide an excellent
environment for training students in state-of-the-art techniques for code optimisation and
data mining and visualisation.

The DiRAC2 HPC facility has been operating since 2012, providing computing resources for theoretical research
in all areas of particle physics, astronomy, cosmology and nuclear physics supported by STFC. It is a highly productive
facility, generating 200-250 papers annually in international, peer-reviewed journals. However, the DiRAC facility risks becoming uncompetitive as it has remained static in terms of overall capability since 2012. The DiRAC-2.5x investment in 2017/18 mitigated the risk of hardware failures, by replacing our oldest hardware components. However, as the factor 5 oversubscription of the most recent RAC call demonstrated, the science programme in 2019/20 and beyond requires a significant uplift in DiRAC's compute capability. The main purpose of the requested funding for the DiRAC2.5y project is to provide a factor 2 increase in computing across all DiRAC services to enable the facility to remain competitive during 2019/20 in anticipation of future funding for DiRAC-3.

DiRAC2.5y builds on the success of the DiRAC HPC facility and will provide the resources needed to support cutting-edge research
during 2019 in all areas of science supported by STFC. While the funding is required to remain competitive, the science programme will continue to be world-leading. Examples of the projects which will benefit from this investment include:

(i) lattice quantum chromodynamics (QCD) calculations of the properties of fundamental particles from first principles;
(ii) improving the potential of experiments at CERN's Large Hadron Collider for discovery of new physics by increasing the accuracy of theoretical predictions for rare processes involving the fundamental constituents of matter known as quarks;
(iii) simulations of the merger of pairs of black holes amnwhich generate gravitational waves such as those recently discovered by the LIGO consortium;
(iv) the most realistic simulations to date of the formation and evolution of galaxies in the Universe;
(v) the accretion of gas onto supermassive black holes, the most efficient means of extracting energy from matter and the engine which drives galaxy evolution;
(vi) new models of our own Milky Way galaxy calibrated using new data from the European Space Agency's GAIA satellite;
(vii) detailed simulations of the interior of the sun and of planetary interiors;
(viii) the formation of stars in clusters - for the first time it will be possible to follow the formation of massive stars.

Planned Impact

The anticipated impact of the DiRAC2.5y HPC facility aligns closely with the recently published UK Industrial Strategy. As such, many of our key impacts will be driven by our engagements with industry. Each service provider for DiRAC2.5y has a local industrial strategy to deliver increased levels of industrial returns over the next three years.
The "Pathways to impact" document which is attached to this proposal describes the overall industrial strategy for the DiRAC facility, including our strategic goals and key performance indicators.

Publications

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Kimm T (2019) Understanding the escape of LyC and Lya photons from turbulent clouds in Monthly Notices of the Royal Astronomical Society

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Komissarov S (2019) Magnetic inhibition of centrifugal instability in Monthly Notices of the Royal Astronomical Society

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Liao S (2019) Ultra-diffuse galaxies in the Auriga simulations in Monthly Notices of the Royal Astronomical Society

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Liu Y (2019) Ring structure in the MWC 480 disk revealed by ALMA in Astronomy & Astrophysics

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Lovell M (2019) The signal of decaying dark matter with hydrodynamical simulations in Monthly Notices of the Royal Astronomical Society

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Lovell M (2019) Simulating the Dark Matter Decay Signal from the Perseus Galaxy Cluster in The Astrophysical Journal Letters

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MacFarlane B (2019) Observational signatures of outbursting protostars - I: From hydrodynamic simulations to observations in Monthly Notices of the Royal Astronomical Society

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MacFarlane B (2019) Observational signatures of outbursting protostars - II. Exploring a wide range of eruptive protostars in Monthly Notices of the Royal Astronomical Society

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Mahmoud R (2019) Reverberation reveals the truncated disc in the hard state of GX 339-4 in Monthly Notices of the Royal Astronomical Society

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Maltman K (2019) Current Status of inclusive hadronic tau determinations of |V_us| in SciPost Physics Proceedings

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Marolf D (2019) Phases of holographic Hawking radiation on spatially compact spacetimes in Journal of High Energy Physics

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Martin G (2019) The formation and evolution of low-surface-brightness galaxies in Monthly Notices of the Royal Astronomical Society

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McAlpine S (2019) The nature of submillimetre and highly star-forming galaxies in the EAGLE simulation in Monthly Notices of the Royal Astronomical Society

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McNally C (2019) Multiplanet systems in inviscid discs can avoid forming resonant chains in Monthly Notices of the Royal Astronomical Society: Letters

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Monachesi A (2019) The Auriga stellar haloes: connecting stellar population properties with accretion and merging history in Monthly Notices of the Royal Astronomical Society

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Muia F (2019) The fate of dense scalar stars in Journal of Cosmology and Astroparticle Physics

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Naik A (2019) Constraints on chameleon f(R)-gravity from galaxy rotation curves of the SPARC sample in Monthly Notices of the Royal Astronomical Society

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Navarro J (2019) Baryon-induced dark matter cores in the eagle simulations in Monthly Notices of the Royal Astronomical Society

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Nealon R (2019) Flyby-induced misalignments in planet-hosting discs in Monthly Notices of the Royal Astronomical Society

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Nishimura (????) N (2019) Uncertainties in ?p-process nucleosynthesis from Monte Carlo variation of reaction rates in Monthly Notices of the Royal Astronomical Society

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Nixon C (2019) What is wrong with steady accretion discs? in Astronomy & Astrophysics

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Pagano P (2019) A New Space Weather Tool for Identifying Eruptive Active Regions in The Astrophysical Journal

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Pfeffer J (2019) The evolution of the UV luminosity function of globular clusters in the E-MOSAICS simulations in Monthly Notices of the Royal Astronomical Society

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Pfeffer J (2019) Young star cluster populations in the E-MOSAICS simulations in Monthly Notices of the Royal Astronomical Society

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Pfeifer S (2020) The bahamas project: effects of a running scalar spectral index on large-scale structure in Monthly Notices of the Royal Astronomical Society

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Pimpanuwat B (2020) Maser flares driven by variations in pumping and background radiation in Monthly Notices of the Royal Astronomical Society

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Pittard J (2019) Momentum and energy injection by a supernova remnant into an inhomogeneous medium in Monthly Notices of the Royal Astronomical Society

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Pittard J (2018) Colliding stellar winds structure and X-ray emission in Monthly Notices of the Royal Astronomical Society

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Power C (2019) nIFTy galaxy cluster simulations VI: the dynamical imprint of substructure on gaseous cluster outskirts. in Monthly Notices of the Royal Astronomical Society