Planetary Giant Impacts
DiRAC resources used: COSMA8 A new understanding of the “canonical” model for Moon formation was provided by Kegerreis et al (2022). Our paper showed that a Moon-sized body can be immediately placed into orbit following the collision of a Mars-sized body, called Theia, with the proto-Earth. Previous low resolution…
Astrophysical Fluid Dynamics at Leeds
Dr Adrian Barker University of Leeds Here are a few science hightlights since our project started on 1st April 2022. Neutron stars are the strongest magnets in the Universe. Their extraordinary magnetic fields are formed during the supernova explosion and continue evolving when neutron star crust solidifies. Magnetic fields…
Massive black holes in dwarf galaxies: from AGN feedback to multimessenger signatures
Contrary to the standard lore, there is mounting observational evidence that feedback from active galactic nuclei (AGN) may also play a role at the low-mass end of the galaxy population. We have explored this possibility with a series of high-resolution zoom-in simulations, varying the AGN prescription and supernova energetics.…
IR-conformal dynamics in SU(2) gauge theories with adjoint fermions
Figure 1: The topological charge distribution of one of the new two-flavour configurations. This image was selected as the winner in the Particle and Nuclear Physics category of the DiRAC 2022 Research Image Competition. Nearly-conformal gauge theories have been singled out as potential avenues for new physicics that can…
Einstein’s Universe: Using numerical relativity to unveil signatures of General Relativity in our cosmological observations
PI: Hayley J Macpherson In cosmology we typically simplify the dynamics of the Universe via the assumption of a homogeneous and isotropic expansion of space-time. While such an assumption is extremely useful and necessary in most application, the dynamics are realistically more complicated. The existence of the large-scale structure…
Signatures of protoplanetary disc warps
Exoplanets form in cold discs of gas and dust around young stars. Our long-standing picture of these so-called protoplanetary discs is that all the planet-forming material orbits in a single plane (as with the planets in the Solar System). However, recent observations with the Hubble Space Telescope, the ESO…
Cosmological constraints on decaying axion-like particles: a global analysis & Finite inflation in curved space
Axion-like particles (ALPs) are a candidate for dark matter, the elusive ‘missing mass’ of the universe, inferred by it’s gravitational presence in galaxies, clusters and cosmological structure formation. As a dark matter candidate, ALPs are preferred by theorists since they are a model independent generalisation of the standard model…
Calculation of the scattering of two Goldstone bosons in the scalar resonance channel for an SU(2) gauge theory with two fundamental fermions.
Understanding the nature of the Standard Model Higgs boson is still an open problem. Extensions of the Standard Model in which its fields have a composite origin provide a compelling first-principle explanation of the existence of the Higgs boson and explain its mass in terms of spontaneous breaking of…
Lattice studies of 3d super-Yang–Mills and holography
DiRAC Project dp162/PPSP311, “Lattice studies of 3d super-Yang–Mills and holography”, is using the Cambridge icelake cluster to explore conjectured holographic dualities that relate supersymmetric quantum field theories to quantum gravity in a higher number of space-time dimensions. Such holographic dualities are widely employed in theoretical physics, and are beginning…
The role of angular momentum in the formation of disk galaxies at high redshift
One of the key factors determining galaxies’ observable properties, such as their morphology and colour, is their angular momentum. However, the origin of this angular momentum remains uncertain. Observations reveal that the spins of neighbouring galaxies are correlated one with another, a signal known as the intrinsic alignment signal.…
Magneto-hydrodynamics in Population III star formation
The gravitational potential of DM halos facilitated the formation of the coolant H2 within baryonic gas, allowing it to cool and collapse. The evolution of the collapse is dominated by the chemistry involved. The dominant chemical processes that complicate the collapse are three-body H2 formation heating, collision-induced emission cooling…
Tracing the small-scale structure of the cosmic web over 12 billion years
A science highlight in 2022 was the development of the first hydrodynamical simulations of the intergalactic medium (IGM) to incorporate heating by dark photons. Photons are the mediator of the electromagnetic force between charged particles, such as electrons and protons. We expect particles in the dark sector to interact…
A study of quantum Lyapunov exponents and their numerical analytic continuation in low-dimensional quantum systems using exact diagonalization
The Banks-Fischler-Shenker-Susskind (BFSS) model is one of the popular microscopic models of black hole dynamics, capable of explaining how black holes scramble information. Studies of the BFSS model suggest that a microscopic mechanism of information scrambling by black holes is related to their intrinsically chaotic dynamics. In particular, BFSS…
Structure formation in fuzzy dark matter
PI: Anastasia Fialkov Filamentary network in FDM. Figure from Dome et al. 2023b. The fuzzy dark matter (FDM) scenario has received increased attention in recent years due to the small-scale challenges of the LCDM cosmological model and the lack of any experimental evidence for any candidate particle. In this…
Spontaneous Symmetry Breaking in the 3d Thirring Model
PI: Simon Hands Institution: University of Liverpool The Thirring Model describes relativistic fermions moving in a two-dimensional plane and interacting via a contact term between conserved currents. The physical system it most resembles is low-energy electronic excitations in graphene. For free electrons at half-filling on a honeycomb lattice, conduction…
The impact of dynamical friction in gas on structure formation in the Universe
Project: dp134Author: Ben Morton (morton@roe.ac.uk)Team members: Prof. Sadegh Khochfar, Dr. Jose Onorbe Dynamical friction is the process by which a massive perturber, moving through some background medium, gravitationally interacts with that medium, producing a net retarding force to its motion. When the background medium is gaseous, the pressure forces…
3D high resolution (10243) hydrodynamics simulation of a type-II supernova explosion
This is a 3D high resolution (10243) hydrodynamics simulation of a type-II supernova explosion using the code AREPO. The outer boundary seen is the forward shock which results from the supernova explosion and which is expanding into a uniform interstellar medium. A number of instabilities develop at the supernova…
The Gravitational Afterglow of Boson Stars
The theoretical framework of our current understanding of the Universe rests on two main pillars, the Standard Model (SM) of particle physics and Einstein’s theory of General Relativity (GR). This SM+GR framework provides us with an incredible power to explain and predict a plethora of phenomena in observations and…
A method to reconstruct magnetic fields from multi-spacecraft measurements
Project title: Heating and Acceleration through Magnetic Reconnection in Space Plasma TurbulencePI: Daniel Verscharen (MSSL, University College London)DiRAC Resource: Data Intensive at Leicester (DIaL) Jeffersson A. Agudelo Rueda, Daniel Verscharen Advances in space technology have led to the dawn of a new era for multi-spacecraft science missions to explore…
Impact crater scaling and inner solar system bombardment
DiRAC resource used: DiAL 2.5 PI: G.S. Collins The relationship between impact crater size and impactor properties, such as size and speed, is key to comparing impactor and crater populations on different planets and dating planetary surfaces. Most of our understanding of this relationship, however, comes from numerical simulations…
The Impact of Galaxy Formation on Dark Matter Halos
The dominant component of matter in the Universe is believed to be dark matter, an unknown subatomic particle that only interacts with ordinary matter via gravity. Through gravitational growth, dark matter forms into so-called halos, within these halos that the visible galaxies we see in the Universe form and…
Effect of stellar fly-bys on young planetary system architectures
The architectures of planetary systems discovered by Kepler are poorly understood. There are far more single-transiting planets than expected from the analysis of the number of multi-transiting systems, assuming that all planetary systems are co-planar. However, stars are not born in isolation, and interactions between stars can perturb their…
Toward a first full test of holographic cosmological models
This project is focused on the study of field theories relevant for building holographic cosmological models. These models use three dimensional QFT to model holographically the laws of physics in the very early universe and make predictions for cosmological observables such as the cosmic microwave background (CMB). Our analysis…
What Role Does Interchange Reconnection Play in the Formation of Magnetic Switchbacks?
Observations from NASA’s Parker Solar Probe (PSP), launched in 2018, have revealed that close to the Sun the solar wind is tremendously variable, much more so than further out in the Heliosphere. This variability primarily takes the form of local reversals of the usually radial magnetic field known as…
Hadron Resonances from Lattice QCD
Understanding and obtaining predictions from Quantum Chromodynamics (QCD), the theory of strongly-interacting quarks and gluons, is one of the foremost problems in particle physics. The vast majority of ordinary strongly-interacting matter is composed of protons and neutrons, themselves composed of light up and down quarks. However, the spectrum of…
Kink-unstable flux ropes in three-dimensional, multi-fluid, partially ionised plasma
Andrew Hillier, Ben Snow, Giulia Murtas The solar atmosphere is a complex and chaotic plasma environment, rife with explosive phenomena driven by the complex magnetic structure undergoing topological changes and releasing this stored energy through a process known as magnetic reconnection. This process readily occurs in the twisted (kinked)…
Discontinuous Galerkin methods and time implicit solver applied to various astrophysical problems
Project dp048 – PI I. Baraffe – Data Intensive Cluster System in Leicester & Cambridge Despite being the most observed star in the Universe, many open questions remain regarding the properties of convection and waves in the deep interior of the Sun. Sophisticated numerical simulations can unveil some important…
Long term planet migration simulations demonstrate an attractor for gas giant planets in 1-10 AU range
The conventional picture of giant planet migration in protoplanetary discs involves an inexorable inspiral towards the star through the process of Type II migration, thus providing a popular scenario for the creation of hot Jupiters. In Scardoni et al 2022[1] we explored very long term (0.6M planetary orbits)[2] simulations…
Vertical cross-section taken from a 3D stellar simulation
The image shows a vertical cross-section taken from a 3D stellar simulation run on the DiRAC Memory Intensive Service. It is possible to see the turbulent motions of the plasma inside the star and how the chemical composition is transported and mixed, represented by the abundance of neon in…
Predicting Signatures of Luminous Remnants for Type Iax Supernovae
Fionntán Callan, Stuart Sim, Christine Collins, Luke Shingles, Joshua Pollin Astrophysics Research Centre, Queen’s University Belfast, Northern Ireland Type Ia supernovae (SNe Ia) are extremely luminous astrophysical events that arise from the thermonuclear explosions of white dwarf stars. They play a number of key roles in astrophysics including acting…
HPQCD: hints of new physics in rare B decays
Figure 1. A possible decay pathway for 𝑩+ → 𝑲+𝒍+𝒍−in the Standard Model. The b quark in the B meson on the left undergoes a transition to an s quark, forming a K meson on the right. This can only happen via a loop containing W bosons and top…
The statistical properties of stars at redshift, z = 5, compared with the present epoch
Matthew Bate (University of Exeter) The distribution of stellar masses, known as the initial mass function (IMF), is of central importance in astrophysics, due to the fact that the radiative, chemical and mechanical feedback from a star depends strongly on its mass. Despite many observational studies, there is little…
Gargantuan black holes at cosmic dawn
High-redshift surveys have so far discovered over a hundred quasars above redshift of six. This number will likely increase significantly in the coming years, due to ongoing and planned deep, wide-field surveys, such as eROSITA in X-rays, the Vera Rubin Observatory at optical wavelengths as well as Euclid in…
High-precision QCD: Quantifying effects from photon exchanges in weak decays
New discoveries in particle physics can be made in different ways. One can let particles collide at higher and higher energies and look for direct evidence of new particles and interactions, or search instead for tiny but measurable discrepancies between experimental measurements and theoretical predictions, at the so-called precision…
Compton Amplitude and Nucleon Structure Functions via the Feynman-Hellmann theorem
Understanding the internal structure of hadrons from first principles remains one of the foremost tasks in particle and nuclear physics. It is an active field of research with important phenomenological implications in high-energy, nuclear and astroparticle physics. The structure of hadrons relevant for deep-inelastic scattering are completely characterized by…
Extreme QCD: Quantifying the QCD Phase Diagram
Project: dp006 Science Highlights 2022 The FASTSUM collaboration uses DiRAC supercomputers to simulate the interaction of quarks, the fundamental particles which make up protons, neutrons and other hadrons. The force which holds quarks together inside these hadrons is Quantum ChromoDynamics, “QCD”. We are particularly interested in the behavior of…
FLAMINGO — A large suite of state-of-the-art galaxy cluster simulations for emulations for high-precision cosmology
Leads: Ian McCarthy, Joop Schaye, Matthieu Schaller & Virgo II The worldwide observational cosmology community is gearing up to receive a real deluge of new data from large survey campaigns currently mapping the sky. This data will allow, for the first time, to put tight constraints on some key…
Virgo-I: The Milky Way’s plane of satellites is consistent with ΛCDM
Till Sawala, Marius Cautun, Carlos Frenk, John Helly, Jens Jasche, Adrian Jenkins, Peter Johansson, Guilhem Lavaux , Stuart McAlpine, Matthieu Schaller Nature Astronomy, in press, 2022NatAs.tmp.273S (arXiv.2205.02860) In the 1970s, the great Cambridge astronomer, the late Professor Donald Lynden-Bell, noted that the 11 bright satellites orbiting the Milky…