A5020847721- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- Calibration and Measurement Techniques
- Superconducting and THz Device Technology
- Atmospheric Ozone and Climate
- Geophysics and Gravity Measurements
- Remote Sensing in Agriculture
- Impact of Light on Environment and Health
- Particle physics theoretical and experimental studies
- Computational Physics and Python Applications
- Particle Detector Development and Performance
- Solar and Space Plasma Dynamics
- Plant Water Relations and Carbon Dynamics
Leiden University
2016-2025
Leiden Observatory
2011-2024
Durham University
2017
University of Colorado System
2015
University of Colorado Boulder
2015
Netherlands Institute for Radio Astronomy
2013
Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
2007
Institute for Advanced Study
2001-2006
Albert Einstein College of Medicine
2001-2006
University of Cambridge
2000-2001
We introduce the Virgo Consortium's EAGLE project, a suite of hydrodynamical simulations that follow formation galaxies and black holes in representative volumes. discuss limitations such light their finite resolution poorly constrained subgrid physics, how these affect predictive power. One major improvement is our treatment feedback from massive stars AGN which thermal energy injected into gas without need to turn off cooling or forces, allowing winds develop predetermined speed mass...
We present results from thirteen cosmological simulations that explore the parameter space of "Evolution and Assembly GaLaxies their Environments" (EAGLE) simulation project. Four follow evolution a periodic cube L = 50 cMpc on side, each employs different subgrid model energetic feedback associated with star formation. The relevant parameters were adjusted so reproduce observed galaxy stellar mass function at z 0.1. Three fail to form disc galaxies as extended observed, we show analytically...
Radiative cooling is central to a wide range of astrophysical problems. Despite its importance, rates are generally computed using very restrictive assumptions, such as collisional ionization equilibrium and solar relative abundances. We simultaneously relax both assumptions investigate the effects photo-ionization heavy elements by meta-galactic UV/X-ray background variations in abundances on optically thin gas equilibrium. find that radiation reduces net up an order magnitude for densities...
(Abridged) We present a method that tracks the growth of supermassive black holes (BHs) and feedback from AGN in cosmological simulations. Our model is substantially modified version one by Springel et al. (2005). Because simulations lack both resolution physics to multiphase interstellar medium, they tend strongly underestimate Bondi-Hoyle accretion rate. To allow low-mass BHs grow, it therefore necessary increase predicted rates dense gas large, ad-hoc factors. explore physical regimes...
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph currently in manufacturing, assembly and integration phase. MUSE has field of 1x1 arcmin2 sampled at 0.2x0.2 arcsec2 assisted by the ground layer adaptive optics ESO facility using four laser guide stars. instrument large 24 identical high performance integral units, each one composed an advanced image slicer, 4kx4k detector. In this paper we review progress manufacturing report...
We present the discovery of three new quasars at z > 6 in ∼ 1300 deg2 Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z = 6.43), J104845.05+463718.3 6.23), and J163033.90+401209.6 6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from positions Lyman break. They only accurate to ∼0.05 could be affected by presence broad absorption line systems. last object has a strength more typical lower redshift quasars. Based on sample six 5.7 that...
We use a combination of three large N-body simulations to investigate the dependence dark matter halo concentrations on mass and redshift in WMAP year 5 cosmology. The median relation between concentration is adequately described by power-law for masses range 10^11 - 10^15 Msol/h redshifts z < 2, regardless whether density profiles are fit using NFW or Einasto profiles. Compared with recent analyses Millennium Simulation, which uses value sigma_8 that higher than allowed WMAP5, = 0 reduced...
We investigate the physics driving cosmic star formation (SF) history using more than fifty large, cosmological, hydrodynamical simulations that together comprise OverWhelmingly Large Simulations (OWLS) project. systematically vary parameters of model to determine which physical processes are dominant and aspects robust. Generically, we find SF is limited by build-up dark matter haloes at high redshift, reaches a broad maximum intermediate then decreases as it quenched lower cooling rates in...
We study global star formation thresholds in the outer parts of galaxies by investigating stability disk embedded dark halos. The disks are self-gravitating, contain metals and dust, exposed to UV radiation. find that critical surface density for existence a cold interstellar phase depends only weakly on parameters model coincides with empirically derived threshold formation. Furthermore, it is shown drop thermal velocity dispersion associated transition from warm gas triggers gravitational...
The Local Group of galaxies offer some the most discriminating tests models cosmic structure formation. For example, observations Milky Way (MW) and Andromeda satellite populations appear to be in disagreement with N-body simulations "Lambda Cold Dark Matter" ({\Lambda}CDM) model: there are far fewer than substructures cold dark matter halos (the "missing satellites" problem); dwarf seem avoid massive "too-big-to-fail" brightest satellites orbit their host on a thin plane "planes problem)....
Cosmological simulations make use of sub-grid recipes for the implementation galactic winds driven by massive stars because direct injection supernova energy in thermal form leads to strong radiative losses, rendering feedback inefficient.We argue that main cause catastrophic cooling is a mismatch between mass gas which injected and parent stellar population.Because too much heated, temperatures are low times short.We analytic arguments estimate, as function density numerical resolution,...
When averaged over large scales, star formation in galaxies is observed to follow the empirical Kennicutt-Schmidt (KS) law for surface densities above a constant threshold. While involves densities, theoretical models and simulations generally work with volume density laws (i.e. Schmidt laws). We derive analytic relations between expressed terms of pressures we show how these depend on parameters such as effective equation state multiphase interstellar medium. Our enable us implement into...
(Abridged) We present an implementation of stellar evolution and chemical feedback for smoothed particle hydrodynamics (SPH) simulations. consider the timed release individual elements by both massive (Type II supernovae winds) intermediate mass stars Ia asymptotic giant branch stars). illustrate results our method using a suite cosmological simulations that include new prescriptions radiative cooling, star formation, galactic winds. Radiative cooling is implemented element-by-element, in...
We use a set of cosmological simulations combined with radiative transfer calculations to investigate the distribution neutral hydrogen in post-reionization Universe. assess contributions from metagalactic ionizing background, collisional ionization and diffuse recombination radiation total rate at redshifts z = 0–5. find that densities above which self-shielding becomes important are consistent analytic previous work. However, because radiation, whose intensity peaks same density,...
We compare the results of thirteen cosmological gasdynamical codes used to simulate formation a galaxy in LCDM structure paradigm. The various runs differ their hydrodynamical treatment (SPH, moving-mesh and AMR) but share same initial conditions adopt latest published model cooling, star feedback. Despite common halo assembly history, we find large code-to-code variations stellar mass, size, morphology gas content at z=0, due mainly different implementations Compared with observation, most...
The evolution of the large-scale distribution matter is sensitive to a variety fundamental parameters that characterise dark matter, energy, and other aspects our cosmological framework. Since majority mass density in form cannot be directly observed, do cosmology with structure one must use observable (baryonic) quantities trace underlying (hopefully) predictable way. However, recent numerical studies have demonstrated mapping between total mass, as well itself, are unresolved feedback...
Feedback from star formation is thought to play a key role in the and evolution of galaxies, but its implementation cosmological simulations currently hampered by lack numerical resolution. We present test sub-grid recipe model feedback massive stars smoothed particle hydrodynamics simulations. The energy distributed kinetic form among gas particles surrounding recently formed stars. impact studied using suite high-resolution isolated disc galaxies embedded dark halos with total mass 10^{10}...
We examine the circular velocity profiles of galaxies in {\Lambda}CDM cosmological hydrodynamical simulations from EAGLE and LOCAL GROUPS projects compare them with a compilation observed rotation curves spanning wide range mass. The shape simulated varies systematically as function galaxy mass, but shows remarkably little variation at fixed maximum velocity. This is especially true for low-mass dark matter-dominated systems, reflecting expected similarity underlying cold matter haloes. odds...
We investigate the evolution of galaxy masses and star formation rates in Evolution Assembly Galaxies their Environment (eagle) simulations. These comprise a suite hydrodynamical simulations Λ cold dark matter cosmogony with subgrid models for radiative cooling, formation, stellar mass-loss feedback from stars accreting black holes. The was calibrated to reproduce observed present-day mass function sizes. Here, we demonstrate that growth density within 20 per cent. also track out redshift z...
We investigate the internal structure and density profiles of halos mass $10^{10}-10^{14}~M_\odot$ in Evolution Assembly Galaxies their Environment (EAGLE) simulations. These follow formation galaxies a $\Lambda$CDM Universe include treatment baryon physics thought to be relevant. The EAGLE simulations reproduce observed present-day galaxy stellar function, as well many other properties population function time. find significant differences between masses that only dark matter component....
We present a new suite of large-volume cosmological hydrodynamical simulations called cosmo-OWLS. They form an extension to the OverWhelmingly Large Simulations (OWLS) project, and have been designed help improve our understanding cluster astrophysics non-linear structure formation, which are now limiting systematic errors when using clusters as probes. Starting from identical initial conditions in either Planck or WMAP7 cosmologies, we systematically vary most important 'sub-grid' physics,...
(Abridged) We study the rate at which gas accretes onto galaxies and haloes investigate whether accreted was shocked to high temperatures before reaching a galaxy. For this purpose we use suite of large cosmological, hydrodynamical simulations from OWLS project. improve on previous work by considering wider range halo masses redshifts, distinguishing accretion galaxies, including important feedback processes, comparing with different physics. The specific is, like that for dark matter, only...
Upcoming weak lensing surveys, such as LSST, EUCLID, and WFIRST, aim to measure the matter power spectrum with unprecedented accuracy.In order fully exploit these observations, models are needed that, given a set of cosmological parameters, can predict non-linear at level 1% or better for scales corresponding comoving wave numbers 0.1 k 10 h Mpc -1 .We have employed large suite simulations from OWLS project investigate effects various baryonic processes on spectrum.In addition, we examined...
[Abridged] The relatively recent insight that energy input from supermassive black holes (BHs) can have a substantial effect on the star formation rates (SFRs) of galaxies motivates us to examine its effects scale galaxy groups. At present, groups contain most and significant fraction overall baryon content universe. To explore BH feedback groups, we analyse two high resolution cosmological hydro simulations OverWhelmingly Large Simulations project. While both include galactic winds driven...