John Magorrian
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View article: Mapping dust in the giant molecular cloud Orion A
Mapping dust in the giant molecular cloud Orion A Open
The Sun is located close to the Galactic mid-plane, meaning that we observe the Galaxy through significant quantities of dust. Moreover, the vast majority of the Galaxy’s stars also lie in the disc, meaning that dust has an enormous impact…
View article: Mapping dust in the giant molecular cloud Orion A
Mapping dust in the giant molecular cloud Orion A Open
The Sun is located close to the Galactic mid-plane, meaning that we observe the Galaxy through significant quantities of dust. Moreover, the vast majority of the Galaxy's stars also lie in the disc, meaning that dust has an enormous impact…
View article: The JWST Galactic Center Survey -- A White Paper
The JWST Galactic Center Survey -- A White Paper Open
The inner hundred parsecs of the Milky Way hosts the nearest supermassive black hole, largest reservoir of dense gas, greatest stellar density, hundreds of massive main and post main sequence stars, and the highest volume density of supern…
View article: On the self-consistent time-dependent linearized response of stellar discs to external perturbations
On the self-consistent time-dependent linearized response of stellar discs to external perturbations Open
We study the explicitly time-dependent response of a razor-thin axisymmetric disc to externally imposed perturbations by recasting the linearized Collisionless Boltzmann equation as an integral equation and applying Kalnajs' matrix method.…
View article: Self-consistent modelling of the Milky Way’s nuclear stellar disc
Self-consistent modelling of the Milky Way’s nuclear stellar disc Open
The nuclear stellar disc (NSD) is a flattened high-density stellar structure that dominates the gravitational field of the Milky Way at Galactocentric radius $30\, {\rm pc}\lesssim R\lesssim 300\, {\rm pc}$. We construct axisymmetric self-…
View article: Stellar dynamics in the periodic cube
Stellar dynamics in the periodic cube Open
We use the problem of dynamical friction within the periodic cube to illustrate the application of perturbation theory in stellar dynamics, testing its predictions against measurements from N-body simulations. Our development is based on t…
View article: Jeans modelling of the Milky Way’s nuclear stellar disc
Jeans modelling of the Milky Way’s nuclear stellar disc Open
The nuclear stellar disc (NSD) is a flattened stellar structure that dominates the gravitational potential of the Milky Way at Galactocentric radii $30 \lesssim R \lesssim 300\, {\rm pc}$. In this paper, we construct axisymmetric Jeans dyn…
View article: Orbit-superposition models of discrete, incomplete stellar kinematics: application to the Galactic centre
Orbit-superposition models of discrete, incomplete stellar kinematics: application to the Galactic centre Open
We present a method for fitting orbit-superposition models to the kinematics\nof discrete stellar systems when the available stellar sample has been filtered\nby a known selection function. The fitting method can be applied to any model\ni…
View article: Large-scale three-dimensional Gaussian process extinction mapping
Large-scale three-dimensional Gaussian process extinction mapping Open
Gaussian processes are the ideal tool for modelling the Galactic ISM, combining statistical flexibility with a good match to the underlying physics. In an earlier paper we outlined how they can be employed to construct three-dimensional ma…
View article: A theoretical explanation for the Central Molecular Zone asymmetry
A theoretical explanation for the Central Molecular Zone asymmetry Open
It has been known for more than thirty years that the distribution of\nmolecular gas in the innermost 300 parsecs of the Milky Way, the Central\nMolecular Zone, is strongly asymmetric. Indeed, approximately three quarters of\nmolecular emi…
View article: Nuclear spirals in the inner Milky Way
Nuclear spirals in the inner Milky Way Open
We use hydrodynamical simulations to construct a new coherent picture for the gas flow in the Central Molecular Zone (CMZ), the region of our Galaxy within R less than or similar to 500 pc. We relate connected structures observed in (l, b,…
View article: The secular evolution of discrete quasi-Keplerian systems
The secular evolution of discrete quasi-Keplerian systems Open
We derive the kinetic equation that describes the secular evolution of a large set of particles orbiting a dominant massive object, such as stars bound to a supermassive black hole or a proto-planetary debris disc encircling a star. Becaus…
View article: A low upper mass limit for the central black hole in the late-type galaxy NGC 4414
A low upper mass limit for the central black hole in the late-type galaxy NGC 4414 Open
We present our mass estimate of the central black hole in the isolated spiral galaxy NGC 4414. Using natural guide star adaptive optics assisted observations with the Gemini Near-Infrared Integral Field Spectrometer (NIFS) and the natural …
View article: The secular evolution of discrete quasi-Keplerian systems. I. Kinetic theory of stellar clusters near black holes
The secular evolution of discrete quasi-Keplerian systems. I. Kinetic theory of stellar clusters near black holes Open
We derive the kinetic equation that describes the secular evolution of a large set of particles orbiting a dominant massive object, such as stars bound to a supermassive black hole or a proto-planetary debris disc encircling a star. Becaus…
View article: Dark Matter Scaling Relations And The Assembly Epoch Of Coma Early-Type Galaxies
Dark Matter Scaling Relations And The Assembly Epoch Of Coma Early-Type Galaxies Open
Axisymmetric, orbit-based dynamical models are used to derive dark matter scaling relations for Coma early-type galaxies. From faint to bright galaxies, halo core radii and asymptotic circular velocities increase. Compared to spirals of th…
View article: Gas flow in barred potentials – III. Effects of varying the quadrupole
Gas flow in barred potentials – III. Effects of varying the quadrupole Open
We run hydrodynamical simulations of a 2D isothermal non-self-gravitating inviscid gas flowing in a rigidly rotating externally imposed potential formed by only two components: a monopole and a quadrupole. We explore systematically the eff…
View article: Secular diffusion in discrete self-gravitating tepid discs II. Accounting for swing amplification via the matrix method
Secular diffusion in discrete self-gravitating tepid discs II. Accounting for swing amplification via the matrix method Open
\n The secular evolution of an infinitely thin tepid isolated galactic disc made of a finite number of particles is investigated using the inhomogeneous Balescu-Lenard equation expressed in terms of angle-action variables. The matrix metho…
View article: Gas flow in barred potentials – II. Bar-driven spiral arms
Gas flow in barred potentials – II. Bar-driven spiral arms Open
Spiral arms that emerge from the ends of a galactic bar are important in interpreting observations of our and external galaxies. It is therefore important to understand the physical mechanism that causes them. We find that these spiral arm…
View article: Gas flow in barred potentials II. Bar Driven Spiral Arms
Gas flow in barred potentials II. Bar Driven Spiral Arms Open
Spiral arms that emerge from the ends of a galactic bar are important in interpreting observations of our and external galaxies. It is therefore important to understand the physical mechanism that causes them. We find that these spiral arm…
View article: Gas flow in barred potentials
Gas flow in barred potentials Open
We use a Cartesian grid to simulate the flow of gas in a barred Galactic\npotential and investigate the effects of varying the sound speed in the gas and\nthe resolution of the grid. For all sound speeds and resolutions, streamlines\nclose…
View article: Marginal likelihoods of distances and extinctions to stars: computation and compact representation
Marginal likelihoods of distances and extinctions to stars: computation and compact representation Open
We present a method for obtaining the likelihood function of distance and\nextinction to a star given its photometry. The other properties of the star\n(its mass, age, metallicity and so on) are marginalised assuming a simple\nGalaxy model…