Publications (30)
N-body simulations of gravitational dynamics
Walter Dehnen, Justin Read
We describe the astrophysical and numerical basis of N-body simulations, both of collisional stellar systems (dense star clusters and galactic centres) and collisionless stellar dy…
Milking the spherical cow: on aspherical dynamics in spherical coordinates
Andrew Pontzen, Justin Read, Romain Teyssier +4
Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analys…
Converging on the eccentricity of massive black hole binaries in galactic mergers
Alessia Gualandris, Justin Read, Federica Fastidio +4
Binaries of supermassive black holes (MBHBs) represent the primary sources of the gravitational wave background (GWB) detectable by Pulsar Timing Arrays (PTAs). The eccentricity wi…
The Merian Survey: Design, Construction, and Characterization of a Filter Set Optimized to Find Dwarf Galaxies and Measure their Dark Matter Halo Properties with Weak Lensing
Yifei Luo, Alexie Leauthaud, Jenny Greene +28
The Merian survey is mapping 850 degrees of the Hyper Suprime-Cam Strategic Survey Program (HSC-SSP) wide layer with two medium-band filters on the 4-meter Victor M. Bla…
The PARADIGM project I: How early merger histories shape the present-day sizes of Milky-Way-mass galaxies
Gandhali D. Joshi, Andrew Pontzen, Oscar Agertz +3
How mergers affect galaxy formation depends on both feedback processes, and on the geometry and strength of the mergers themselves. We introduce the PARADIGM project, where we stud…
Theia: Faint objects in motion or the new astrometry frontier
The Theia Collaboration, Celine Boehm, Alberto Krone-Martins +96
In the context of the ESA M5 (medium mission) call we proposed a new satellite mission, Theia, based on relative astrometry and extreme precision to study the motion of very faint…
Defeating stochasticity: coalescence timescales of massive black holes in galaxy mergers
Imran Nasim, Alessia Gualandris, Justin Read +3
The coalescence of massive black hole binaries (BHBs) in galactic mergers is the primary source of gravitational waves (GWs) at low frequencies. Current estimates of GW detection r…
Halo heating from fluctuating gas in a model dwarf
Mahmoud Hashim, Amr El-Zant, Jonathan Freundlich +2
The cold dark matter (CDM) structure formation scenario faces challenges on (sub)galactic scales, central among them being the `cusp-core' problem. A known remedy, driving CDM out…
Thermal instabilities in cooling galactic coronae: fuelling star formation in galactic discs
Alexander Hobbs, Justin Read, Chris Power +1
We investigate the means by which cold gas can accrete onto Milky Way mass galaxies from a hot corona of gas, using a new smoothed particle hydrodynamics code, 'SPHS'. We find that…
VINTERGATAN-GM: How do mergers affect the satellite populations of MW-like galaxies?
Gandhali D. Joshi, Andrew Pontzen, Oscar Agertz +3
We investigate the impact of a galaxy's merger history on its system of satellites using the new \textsc{vintergatan-gm} suite of zoom-in hydrodynamical simulations of Milky Way-ma…
VINTERGATAN-GM: long-lived satellite planes induced by a massive GSE-like merger
R. RodrÃguez-Cardoso, S. Roca-FÃ brega, Oscar Agertz +7
Satellite galaxies in the Local Group tend to be distributed in thin, planar configurations, with many sharing coherent orbital motion. Galaxy formation simulations in CDM have…
Antlia2's role in driving the ripples in the outer gas disk of the Galaxy
Sukanya Chakrabarti, Philip Chang, Adrian Price-Whelan +3
We employ the earlier published proper motions of the newly discovered Antlia 2 dwarf galaxy derived from Gaia data to calculate its orbital distribution in the cosmologically rece…
The alignment is in their stars: on the spin-alignment of stars in star clusters
Ramon Rey-Raposo, Justin Read
We simulate star formation in two molecular clouds extracted from a larger disc-galaxy simulation with a spatial resolution of ~0.1 pc, one exiting a spiral arm dominated by compre…
Growing galaxies via superbubble-driven accretion flows
Alexander Hobbs, Justin Read, Andrina Nicola
We use a suite a cooling halo simulations to study a new mechanism for rapid accretion of hot halo gas onto star-forming galaxies. Correlated supernovae events create converging 's…
Trial by FIRE: Probing the dark matter density profile of dwarf galaxies with GraphNPE
Tri Nguyen, Justin Read, Lina Necib +4
The Dark Matter (DM) distribution in dwarf galaxies provides crucial insights into both structure formation and the particle nature of DM. GraphNPE (Graph Neural Posterior Estimato…
Cosmology and Fundamental Physics with the Euclid Satellite
Luca Amendola, Stephen Appleby, Anastasios Avgoustidis +69
Euclid is a European Space Agency medium class mission selected for launch in 2020 within the Cosmic Vision 2015 2025 program. The main goal of Euclid is to understand the origin o…
The Causes of Halo Shape Changes Induced by Cooling Baryons: Disks Versus Substructures
Victor P. Debattista, Ben Moore, Thomas Quinn +5
Cold dark matter cosmogony predicts triaxial dark matter halos, whereas observations find quite round halos. This is most likely due to the condensation of baryons leading to round…
Realistic consecutive galaxy mergers form eccentric PTA sources
Federica Fastidio, Elisa Bortolas, Alessia Gualandris +3
Results from pulsar timing arrays (PTAs) show evidence of a gravitational wave background (GWB) consistent with a population of unresolved supermassive black hole binaries (BHBs).…
Dark Matter in Draco and Boötes I: Hints of a Core in an Ultra-Faint Dwarf from Simulation-Based Inference
Tri Nguyen, Lina Necib, Ting S. Li +8
The density profiles of dwarf spheroidal galaxies are among the most sensitive probes of dark matter physics, yet extracting them from noisy stellar kinematics remains a fundamenta…
The local dark sector. Probing gravitation's low-acceleration frontier and dark matter in the Solar System neighborhood
Joel Bergé, Laura Baudis, Philippe Brax +18
We speculate on the development and availability of new innovative propulsion techniques in the 2040s, that will allow us to fly a spacecraft outside the Solar System (at 150 AU an…
Dark Matter Disc Enhanced Neutrino Fluxes from the Sun and Earth
Tobias Bruch, Annika H. G. Peter, Justin Read +2
As disc galaxies form in a hierarchical cosmology, massive merging satellites are preferentially dragged towards the disc plane. The material accreted from these satellites forms a…
The PARADIGM project II: The lifetimes and quenching of satellites in Milky Way-mass haloes
Gandhali D. Joshi, Andrew Pontzen, Oscar Agertz +2
The abundance and star-formation histories of satellites of Milky Way (MW)-like galaxies are linked to their hosts' assembly histories. To explore this connection, we use the PARAD…
Cusp-core transformations in dwarf galaxies: observational predictions
Romain Teyssier, Andrew Pontzen, Yohan Dubois +1
The presence of a dark matter core in the central kiloparsec of many dwarf galaxies has been a long standing problem in galaxy formation theories based on the standard cold dark ma…
Fundamental differences between SPH and grid methods
Oscar Agertz, Ben Moore, Joachim Stadel +17
We have carried out a hydrodynamical code comparison study of interacting multiphase fluids. The two commonly used techniques of grid and smoothed particle hydrodynamics (SPH) show…
Unlocking the physics of dwarf galaxies in the 2040s: The case for a next-generation wide-field spectroscopic facility with fibres and IFUs
Crescenzo Tortora, Daniela Carollo, Leslie Hunt +25
Dwarf galaxies () are the most numerous galaxies in the Universe and critical probes of dark matter, baryonic feedback, and galaxy formation. D…
Transformational astrophysics and exoplanet science with Habitable Worlds Observatory's High Resolution Imager
Vincent Van Eylen, Richard Massey, Saeeda Awan +167
Habitable Worlds Observatory (HWO) will be NASA's flagship space telescope of the 2040s, designed to search for life on other planets and to transform broad areas of astrophysics.…
How much can we learn from resolved stellar kinematics of galactic haloes using action-based dynamical models?
Paula Gherghinescu, Eugene Vasiliev, Payel Das +1
Dynamical models are used to study dark matter (DM) in galaxies, how galaxies assemble through mergers, and to test galaxy formation models. Despite its widespread use, there has b…
Cosmology and fundamental physics with the Euclid satellite
Luca Amendola, Stephen Appleby, David Bacon +60
Euclid is a European Space Agency medium class mission selected for launch in 2019 within the Cosmic Vision 2015-2025 programme. The main goal of Euclid is to understand the origin…
Resolving Globular Cluster Formation within a Cosmological Context
Aaron C. Boley, George Lake, Justin Read +1
We place constraints on the formation redshifts for blue globular clusters (BGCs), independent of the details of hydrodynamics and population III star formation. The observed radia…
Novel Adaptive softening for collisionless N-body simulations: Eliminating spurious halos
Alexander Hobbs, Justin Read, Oscar Agertz +2
We describe a NOVel form of Adaptive softening (NovA) for collisionless -body simulations, implemented in the Ramses adaptive mesh refinement code. We introduce a refinement cri…