A5002224962- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- History and Developments in Astronomy
- Plant Water Relations and Carbon Dynamics
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Impact of Light on Environment and Health
- Solar and Space Plasma Dynamics
- Phase Equilibria and Thermodynamics
- Pulsars and Gravitational Waves Research
- Advanced Measurement and Metrology Techniques
- Adhesion, Friction, and Surface Interactions
- Atmospheric Ozone and Climate
- Experimental and Theoretical Physics Studies
University of Central Lancashire
2016-2025
University of Malta
2013-2024
University of Central Lancashire Cyprus
2023
University of Zurich
2008-2018
University of Washington
2005-2010
University of Oxford
2010
Herzberg Institute of Astrophysics
2010
Center for Astrophysics Harvard & Smithsonian
2010
University of Cambridge
2010
Capgemini (United States)
2010
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of exciting science opportunities next decade. The Large Synoptic Survey Telescope (LSST) have an effective aperture 6.7 meters and imaging camera field view 9.6 deg^2, be devoted ten-year 20,000 deg^2 south +15 deg. Each pointing imaged 2000 times fifteen second exposures six broad from 0.35 1.1 microns, total point-source depth r~27.5. LSST Science Book describes basic...
Stars in disks of spiral galaxies are usually assumed to remain roughly at their birth radii. This assumption is built into decades modelling the evolution stellar populations our own Galaxy and external systems. We present results from self-consistent high-resolution $N$-body + Smooth Particle Hydrodynamics simulations disk formation, which stars migrate across significant galactocentric distances due resonant scattering with transient arms, while preserving circular orbits. investigate...
We have performed a high mass and force resolution simulation of an idealized galaxy forming from dissipational collapse gas embedded in spherical dark matter halo. The includes star formation effects stellar feedback. In our disk forms with surface density profile consisting inner exponential breaking to steeper outer exponential. break early on persists throughout the evolution, moving outward as more is able cool add disk. parameters are excellent agreement observations. corresponds rapid...
We present a comprehensive series of $N$-body as well + SPH simulations to study the secular evolution structure disk galaxies. Our are organized in hierarchy increasing complexity, ranging from rigid-halo collisionless fully live with gas and star formation. Comparisons between different types allow us isolate role various physical mechanisms. focus on systems expected LCDM universe. goal is examine which structural properties galaxies may result rather than direct hierarchical assembly. In...
In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with general aim of delivering stellar parameters and elemental abundances for large samples Galactic stars, complementing Gaia astrometry. Among those surveys, Gaia-ESO Public Spectroscopic Survey (GES), only one performed on a 8m class telescope, was designed to target 100,000 stars using FLAMES ESO VLT (both Giraffe UVES spectrographs), covering all Milky Way populations, special focus open...
We show that bars in galaxy models having halos of moderate density and a variety velocity distributions all experience strong drag from dynamical friction unless the halo has large angular momentum same sense as disk. The frictional decreases bar pattern speed, driving corotation point out to distances well excess those estimated barred galaxies. required avoid braking is unrealistically large, even when rotation confined inner only. conclude, therefore, are able maintain their observed...
In a LCDM cosmology, the Milky Way accretes satellites into stellar disc. We use cosmological simulations to assess frequency of near disc plane and higher inclination accretion events, collisionless satellite mergers quantify final state accreted material effect on thin On average, Way-sized galaxy has 3 subhalos with vmax>80km/s; 7 vmax>60km/s; 15 vmax>40km/s merge at redshift z>1. Assuming isotropic accretion, third these an impact angle <20 degrees are dragged by dynamical...
We use fully self-consistent N-body simulations of barred galaxies to show that dynamical friction from a dense dark matter halo dramatically slows the rotation rate bars. Our result supports previous theoretical predictions for bar rotating within massive halo. On other hand, low-density halos, such as those required maximum disks, allow continue rotate at high rate. There is somewhat meager observational evidence indicating bars in real do rapidly, and we our argue halos must have low...
The separation of the Milky Way disk into a thin and thick component is supported by differences in spatial, kinematic metallicity distributions their stars. These have led to view that formed early via cataclysmic event constitutes fossil evidence hierarchical growth Way. We show here, using N-body simulations, how double-exponential vertical structure, with stellar populations displaying similar dichotomies can arise purely through internal evolution. In this picture, stars migrate...
The recent discovery of hidden non-axisymmetric and disc-like structures in bright Virgo dwarf elliptical lenticular galaxies (dE/dSph/dS0) indicates that they may have late-type progenitors. Using N-body simulations we follow the evolution disc within a Λ cold dark matter (ΛCDM) cluster simulated with 107 particles, where hierarchical growth galaxy harassment are modelled self-consistently. Most undergo significant morphological transformation, even at outskirts cluster, move through Hubble...
Cold dark matter cosmogony predicts triaxial halos, whereas observations find quite round halos. This is most likely due to the condensation of baryons leading rounder We examine halo phase space distribution basis for such shape changes. Triaxial halos are supported by box orbits, which pass arbitrarily close density center. The decrease in triaxiality caused thought be scattering these orbits. test this hypothesis with simulations disks grown inside After we check whether structure has...
We present a novel interpretation of the previously puzzling different behaviours stellar populations Milky Way’s bulge. first show, by means pure N-body simulations, that initially co-spatial with in-plane random motions separate when bar forms. The radially cooler form strong bar, and are vertically thin peanut-shaped, while hotter weaker become thicker box. demonstrate it is radial, not vertical, velocity dispersion dominates this evolution. Assuming early discs heat rapidly as they form,...
(Abridged) We perform dissipationless N-body simulations to elucidate the dynamical response of thin disks bombardment by cold dark matter (CDM) substructure. Our method combines (1) cosmological formation Milky Way (MW)-sized CDM halos derive properties substructure and (2) controlled numerical experiments consecutive subhalo impacts onto an initially-thin, fully-formed MW type disk galaxy. The present study is first account for evolution satellite populations over cosmic time in such...
We examine the nuclear morphology, kinematics, and stellar populations in nearby S0 galaxy NGC 404 using a combination of adaptive optics assisted near-IR integral-field spectroscopy, optical Hubble Space Telescope imaging. These observations enable study nucleus at level detail possible only nearest galaxies. The surface brightness profile suggests presence three components: bulge, star cluster (NSC), central light excess within radii < 3 pc. components have distinct kinematics with modest...
We seek to understand the origin of radial migration in spiral galaxies by analyzing detail structure and evolution an idealized, isolated galactic disk. To redistribution stars, we characterize time-evolution properties spirals that spontaneously form Our models unambiguously show such disks, single are unlikely, but a number transient patterns may coexist However, also while amplitude, at any given time disk favors certain pattern speeds. Using several runs with different numerical...
We present a detailed study of the nuclear star clusters (NSCs) and massive black holes (BHs) four nearest low-mass early-type galaxies: M32, NGC205, NGC5012, NGC5206. measure dynamical masses both BHs NSCs in these galaxies using Gemini/NIFS or VLT/SINFONI stellar kinematics, Hubble Space Telescope (HST) imaging, Jeans Anisotropic Models. detect NGC5102, NGC5206, while we find only an upper limit. These BH mass estimates are consistent with previous measurements M32 those NGC5102 NGC5206...
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, across half the sky over ten years repeated observation. However, exactly how LSST observations be taken (the observing strategy or "cadence") not yet finalized. In this dynamically-evolving community white paper, we explore detailed performance anticipated science expected depend on small changes strategy. Using...
The disc structure of the Milky Way is marked by a chemical dichotomy, with high-alpha and low-alpha abundance sequences, traditionally identified geometric thick thin discs. This identification aided old ages stars, lower average ones. Recent large scale surveys such as APOGEE have provided wealth data on this structure, including showing that an discs not exact, but origin dichotomy has remained unclear. Here we demonstrate arises naturally if early gas-rich fragments, leading to some...
We study the physical properties of ionized gas in local disks using sample 38 nearby $\sim10^{8.5-11.2}$M$_\odot$ Star-Forming Main Sequence (SFMS) galaxies observed so far as part MUSE Atlas Disks (MAD). Specifically, we use all strong emission lines wavelength range 4650-9300 \AA\ to investigate resolved on $\sim$100 pc scales. This spatial resolution enables us disentangle HII regions from Diffuse Ionized Gas (DIG) computation metallicities and Star Formation Rates (SFRs) star forming...
Abstract The Milky Way (MW) stellar halo contains relics of ancient mergers that tell the story our galaxy’s formation. Some them are identified due to their similarity in energy, actions, and chemistry, referred as “chemodynamical space,” often attributed distinct merger events. It is also known galaxy went through a significant event shaped local during its first billion years. Previous studies using N -body only cosmological hydrodynamical simulations have shown such single massive can...
Abstract The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, Aerospace Agency. JASMINE has two main goals. One Galactic archaeology with Center survey, which aims to reveal Milky Way’s central core structure formation history from Gaia-level (∼25 ${\mu} $as) astrometry in near-infrared (NIR) Hw band (1.0–1.6 $m). other an exoplanet discover transiting Earth-like exoplanets...
Abstract We study azimuthal variations in the mean stellar metallicity, $\left&lt;{\mbox{$\rm [Fe/H]$}}\right&gt;$, a self-consistent, isolated simulation which all stars form out of gas. find [Fe/H]$}}\right&gt;$ comparable to those observed Milky Way and are coincident with spiral density waves. The present young old therefore not result recently formed stars. Similar age $\rm \alpha$-abundance. measure pattern speeds [Fe/H]$}}\right&gt;$-variations that they match spirals,...
We find nine nuclear cluster candidates in a sample of 14 edge-on, late-type galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys.These clusters have magnitudes (M I $ À11) and sizes (r eA 3 pc) similar to those found previous studies face-on, spirals dE galaxies.However, three are significantly flattened show evidence multiple, coincident structural components.The elongations these aligned within $10 galaxies' major axes.Structurally, well fit by combination...
We analyze the effect of dissipation on orbital evolution supermassive black holes (SMBHs) using high-resolution self-consistent gasdynamical simulations binary equal- and unequal-mass mergers disk galaxies. The galaxy models are consistent with LCDM paradigm structure formation include effects radiative cooling star formation. find that equal-mass always lead to a close SMBH pair at center remnant separations limited solely by adopted force resolution ~ 100 pc. Instead, final separation in...
We describe a made-to-measure algorithm for constructing N-particle models of stellar systems from observational data (Chi-Squared-M2M), extending earlier ideas by Syer and Tremaine. The properly accounts errors, is flexible, can be applied to various geometries. implement this in parallel code NMAGIC carry out sequence tests illustrate its power performance: (i) reconstruct an isotropic Hernquist model density moments projected kinematics recover the correct differential energy distribution...