A5060551274- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Cryospheric studies and observations
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Remote Sensing and Land Use
- Calibration and Measurement Techniques
- Gamma-ray bursts and supernovae
- X-ray Diffraction in Crystallography
- Climate change and permafrost
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Remote Sensing and LiDAR Applications
- Geological Studies and Exploration
- Infrared Target Detection Methodologies
- Astrophysics and Cosmic Phenomena
- Atmospheric and Environmental Gas Dynamics
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Remote-Sensing Image Classification
- Geochemistry and Geologic Mapping
- Electron and X-Ray Spectroscopy Techniques
- Scientific Research and Discoveries
- Environmental Changes in China
- CCD and CMOS Imaging Sensors
Royal Observatory
2014-2025
University of Edinburgh
2014-2025
UK Astronomy Technology Centre
2014-2024
San Diego Supercomputer Center
2016-2020
University of California, San Diego
2010-2020
Michigan State University
2010-2014
University of Colorado Boulder
1990-2011
Laboratory for Atmospheric and Space Physics
2009-2011
Pennsylvania State University
2006-2010
University of Florida
2010
The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set challenges: reproducibility, parallelization, vast increases in data size complexity chief among them. In order to meet these challenges, open up new avenues for collaboration between users multiple simulation platforms, we present yt (available at http://yt.enzotools.org/), an source, community-developed visualization toolkit. Analysis with are oriented around physically relevant...
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...
This paper describes the open-source code Enzo, which uses block-structured adaptive mesh refinement to provide high spatial and temporal resolution for modeling astrophysical fluid flows. The is Cartesian, can be run in one, two, three dimensions, supports a wide variety of physics including hydrodynamics, ideal non-ideal magnetohydrodynamics, N-body dynamics (and, more broadly, self-gravity fluids particles), primordial gas chemistry, optically thin radiative cooling metal-enriched plasmas...
Although galaxies, groups, and clusters contain ∼10% of the baryons, many more reside in photoionized shocked-heated intergalactic medium (IGM) circumgalactic (CGM). We update baryon census (H i) Lyα forest warm-hot IGM (WHIM) at 105–6 K traced by O vi λ1032, 1038 absorption. From Enzo cosmological simulations heating, cooling, metal transport, we improve H i surveys using spatially averaged corrections for metallicity (Z/Z☉) ionization fractions (fH i, fO vi). Statistically, correction...
Starlight from galaxies plays a pivotal role throughout the process of cosmic reionisation. We present statistics dwarf galaxy properties at z > 7 in haloes with masses up to 10^9 solar masses, using cosmological radiation hydrodynamics simulation that follows their buildup starting Population III progenitors. find metal-enriched star formation is not restricted atomic cooling ($T_{\rm vir} \ge 10^4$ K) haloes, but can occur down ~10^6 especially neutral regions. Even though these smallest...
We present the Grackle chemistry and cooling library for astrophysical simulations models. provides a treatment of non-equilibrium primordial H, D, He species, including H2 formation on dust grains; tabulated metal cooling; multiple UV background models; support radiation transfer arbitrary heat sources. The has an easily implementable interface simulation codes written in C, C++, Fortran as well Python with added convenience functions semi-analytical As open-source project, community...
We introduce the AGORA project, a comprehensive numerical study of well-resolved galaxies within LCDM cosmology. Cosmological hydrodynamic simulations with force resolutions ~100 proper pc or better will be run variety code platforms to follow hierarchical growth, star formation history, morphological transformation, and cycle baryons in out 8 halo masses M_vir ~= 1e10, 1e11, 1e12, 1e13 Msun at z=0 two different ("violent" "quiescent") assembly histories. The techniques implementations used...
We assess the probable redshift (zrei ≈ 7) for full reionization of intergalactic medium (IGM) using a prescription comoving star formation rate (SFR) density () required to maintain photoionization against recombination. Our newly developed online simulator allows users SFR and ionization histories, variety assumptions galactic stellar populations, IGM clumping factor temperature, Lyman continuum (LyC) escape fraction. The decline in high-redshift galaxy candidates Lyα emitters at z = 6–8...
We present a simulation of the formation earliest Population II stars, starting from cosmological initial conditions and ending when metals created in first supernovae are incorporated into collapsing gas-cloud. This occurs after supernova blast-wave collides with nearby mini-halo, inducing further turbulence that efficiently mixes dense gas center halo. The collapses has been enriched to metallicity Z ~ 2e-5 Zsun. Due extremely low metallicity, collapse proceeds similarly metal-free until...
Simulations of the formation Population III (Pop III) stars suggest that they were much more massive than Pop II and I observed today. This is due to collapse dynamics metal-free gas, which regulated by radiative cooling molecular hydrogen. We study how gas clouds altered addition metals star-forming environment performing a series simulations pre-enriched star at various metallicities. To make clean comparison with formation, we use initial conditions identical simulation, low ionization no...
Massive stars provide feedback that shapes the interstellar medium of galaxies at all redshifts and their resulting stellar populations. Here we present three adaptive mesh refinement radiation hydrodynamics simulations illustrate impact momentum transfer from ionising to absorbing gas on star formation in high-redshift dwarf galaxies. Momentum is calculated by solving radiative equation with a ray tracing algorithm spatial angular coordinates. We find input partially affects increasing...
Cosmological hydrodynamical simulations of galaxy evolution are increasingly able to produce realistic galaxies, but the largest hurdle remaining is in constructing subgrid models that accurately describe behavior stellar feedback.As an alternate way test and calibrate such models, we propose focus on circumgalactic medium.To do so, generate a suite adaptive-mesh refinement (AMR) for Milky-Way-massed run z = 0, systematically varying feedback implementation.We then post-process simulation...
We describe cosmological galaxy formation simulations with the adaptive mesh refinement code Enzo that incorporate a star prescription regulated by local abundance of molecular hydrogen. show this H2-regulated leads to suppression in low mass halos (M_h < ~10^10 M_sun) at z>4, alleviating some dwarf problems faced theoretical models. H2 regulation modifies efficiency cold gas directly, rather than indirectly reducing content "supernova feedback". determine our most refined grid cells (76...
We present simulations from the new "Figuring Out Gas & Galaxies in Enzo" (FOGGIE) project. In contrast to most extant of galaxy formation, which concentrate computational resources on galactic disks and spheroids with fluid particle elements fixed mass, FOGGIE focus extreme spatial mass resolution circumgalactic medium (CGM) surrounding galaxies. Using Enzo code a refinement scheme, reaches resolutions 381 comoving $h^{-1}$ pc resolves extremely low masses ($\lesssim 1$--$100$ Msun out 100...
ABSTRACT We use high-quality, medium-resolution Hubble Space Telescope /Cosmic Origins Spectrograph ( HST /COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts z AGN < 0.85 to construct the largest survey low-redshift intergalactic medium (IGM) date: 5138 individual extragalactic absorption lines in H i and 25 different metal-ion species grouped into 2611 distinct redshift systems abs 0.75 covering total pathlengths Δ = 21.7 O vi 14.5. Our semi-automated...
The formation of stellar mass black holes from the remnants Population III stars provides a source initial hole seeds with potential to grow into intermediate or, in rare cases, possibly supermassive holes. We use Renaissance simulation suite follow growth over 15,000 born mini-haloes early Universe. compute evolution by post-processing individual remnant star particles snapshots. populate haloes 10$^{6}$ M$_{\odot}$ up 10$^{9}$ M$_{\odot}$. find that all display very inefficient growth. On...
Traditional cosmological hydrodynamics simulations fail to spatially resolve the circumgalatic medium (CGM), reservoir of tenuous gas surrounding a galaxy and extending its virial radius. We introduce technique Enhanced Halo Resolution (EHR), enabling more realistic physical modeling simulated CGM by consistently forcing refinement smaller scales throughout halo galaxy. investigate effects EHR in Tempest simulations, suite Enzo-based zoom following evolution an L* galaxy, resolving spatial...
Abstract We present measurements of the rest-frame UV spectral slope, β , for a sample 36 faint star-forming galaxies at z ∼ 9–16 discovered in one deepest JWST NIRCam surveys to date, Next Generation Deep Extragalactic Exploratory Public Survey. use robust photometric UV-faint (down M −16), originally published Leung et al., and measure values slope via power-law fitting both observed photometry stellar population models obtained through energy distribution (SED) with Bagpipes . obtain...
The advent of new and near-future observatories probing the earliest epochs Universe has opened opportunity to investigate formation growth first massive black holes (MBHs). Additionally, use high resolution cosmological simulations these high-redshift environments is needed predict dark matter halos in which MBH seeds will form. We <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mtext mathvariant="italic">𝑅𝑒𝑛𝑎𝑖𝑠𝑠𝑎𝑛𝑐𝑒</mml:mtext></mml:math> analyse so-called...
We investigate through hydrodynamic simulations the destruction of newly formed dust grains by sputtering in reverse shocks supernova (SN) remnants. Using an idealized setup a planar shock impacting dense, spherical clump, we implant population Lagrangian particles into clump to represent distribution size and composition. then post-process simulation output calculate grain for variety species distributions. explore parameter space appropriate this problem altering overdensity ejecta clumps...
We perform a series of cosmological simulations using Enzo, an Eulerian adaptive-mesh refinement, N-body + hydrodynamical code, applied to study the warm/hot intergalactic medium. The WHIM may be important component baryons missing observationally at low redshift. investigate dependence global star formation rate and mass fraction in various baryonic phases on spatial resolution methods incorporating stellar feedback. Although both feedback significantly affect total WHIM, all our find that...
We report ultraviolet spectra of the high-redshift (zem ≈ 2.9) quasar, HE 2347 − 4342, taken by Cosmic Origins Spectrograph (COS) on Hubble Space Telescope. Spectra in G130M (medium resolution, 1135–1440 Å) and G140L (low 1030–2000 gratings exhibit patchy Gunn–Peterson absorption 303.78 Å Lyα line He ii between z = 2.39–2.87 (G140L) 2.74–2.90 (G130M). With COS, we obtain better spectral higher signal-to-noise ratio (S/N), determined backgrounds than previous studies, with sensitivity to...
Direct collapse black holes (DCBH) have been proposed as a solution to the challenge of assembling supermassive by $z>6$ explain bright quasars observed at this epoch. The formation DCBH seed with $\rm M_{BH}\sim10^{4-5}\ \rm M_{\odot}$ requires pristine atomic-cooling halo be illuminated an external radiation field that is sufficiently strong entirely suppress H$_{2}$ cooling in halo. Many previous studies attempted constrain critical specific intensity likely required cooling, denoted...
We simulate the evolution of a 109 M⊙ dark matter halo in cosmological setting with an adaptive mesh refinement code as analogue to local low-luminosity dwarf irregular and spheroidal galaxies. The primary goal our study is investigate roles reionization supernova feedback determining star-formation histories low-mass include wide range physical effects, including metal cooling, molecular hydrogen formation photoionization photodissociation from metagalactic (but not local) background,...
Enzo (Enzo Developers, 2019a) is a block-structured adaptive mesh refinement code that widely used to simulate astrophysical fluid flows (primarily, but not exclusively, cosmological structure formation, star and turbulence).The community project with dozens of users, has contributed hundreds peer-reviewed publications in astrophysics, physics, computer science.The utilizes Cartesian can be run one, two, or