A5100782716- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Molecular Spectroscopy and Structure
- SAS software applications and methods
- Atmospheric Ozone and Climate
- Atomic and Molecular Physics
- Spectroscopy and Laser Applications
- Astrophysics and Cosmic Phenomena
- Advanced Combustion Engine Technologies
- Astronomical Observations and Instrumentation
- Optical properties and cooling technologies in crystalline materials
- Astrophysical Phenomena and Observations
- Laser-Plasma Interactions and Diagnostics
- Scientific Research and Discoveries
- Cold Atom Physics and Bose-Einstein Condensates
- High-pressure geophysics and materials
- Advanced X-ray Imaging Techniques
- Laser-induced spectroscopy and plasma
- Solid State Laser Technologies
- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
Heidelberg University
2010-2025
University of Manchester
2015-2024
University of St Andrews
2008-2024
Manchester Metropolitan University
2024
Scottish Universities Physics Alliance
2008-2023
Heidelberg Institute for Theoretical Studies
2010-2013
Keele University
2010-2012
University of Cambridge
1999-2012
The University of Texas at Austin
2010
Max Planck Institute for Astrophysics
2010
The cosmic dark ages ended a few hundred million years after the big bang, when first stars began to fill universe with new light. It has generally been argued that these formed in isolation and were extremely massive—perhaps 100 times as massive Sun. In recent study, Clark collaborators showed this picture requires revision. They demonstrated accretion disks build up around Population III are strongly susceptible fragmentation should therefore form clusters rather than isolation. We here...
The very first stars to form in the Universe heralded an end cosmic dark ages and introduced new physical processes that shaped early evolution. Until now, it was thought these lived short, solitary lives, with only one extremely massive star, or possibly a wide binary system, forming each matter minihalo. Here we describe numerical simulations show were, contrary, often members of tight multiple systems. Our results disks formed around young were unstable gravitational fragmentation,...
In this paper a simple model for the steady state evolution of debris disks due to collisions is developed and confronted with properties emerging population seven Sun-like stars that have hot dust at <10 AU. The shows there maximum possible disk mass given age, since more massive primordial process their faster. corresponding luminosity fmax = 0.16 × 10-3r7/3t, where r radius in AU tage system age Myr. majority (4/7) exceed limit by ≫1000 so cannot be products asteroid belts; rather,...
We investigate the formation of first stars at end cosmic dark ages with a suite three-dimensional, moving-mesh simulations that directly resolve collapse gas beyond protostar centre matter minihalo. The cover more than 25 orders magnitude in density and have maximum spatial resolution 0.05 R⊙, which extends well below radius individual protostars captures their interaction surrounding gas. In analogy to previous studies employed sink particles, we find Keplerian disc around primary...
The PHANGS collaboration has been building a reference dataset for the multi-scale, multi-phase study of star formation and interstellar medium in nearby galaxies. With successful launch commissioning JWST, we can now obtain high-resolution infrared imaging to probe youngest stellar populations dust emission on scales clusters molecular clouds ($\sim$5-50 pc). In Cycle 1, is conducting an 8-band survey from 2-21$\mu$m 19 spiral CO(2-1) mapping, optical integral field spectroscopy, UV-optical...
In this paper a simple analytical model for the steady-state evolution of debris disks due to collisions is confronted with Spitzer observations main sequence A stars. All stars are assumed have planetesimal belts distribution initial masses and radii. disk mass constant until largest planetesimals reach collisional equilibrium whereupon falls off oc 1/t. We find that detection statistics trends seen at both 24 70um can be fitted well by model. While there no need invoke stochastic or...
We use the moving mesh code arepo coupled to a time-dependent chemical network investigate molecular gas in simulated spiral galaxies that is not traced by CO emission. calculate H2 and column densities, estimate emission CO–H2 conversion factor. find conditions akin those local interstellar medium, around 42 per cent of total mass should be CO-dark regions, reasonable agreement with observational estimates. This fraction almost insensitive CO-integrated intensity threshold used discriminate...
We show that massive stars and stellar clusters are formed simultaneously, the global evolution of forming cluster is what allows central to become massive. predict star clumps, such as those observed in Motte et al. 2007, contract grow mass leading formation stars. This occurs continually channeled from large radii onto proto-stars, which can through accretion. Using SPH simulations clumps a Giant Molecular Cloud, we initially diffuse filamentary, more concentrated they collapse. Simulated...
We use a suite of high-resolution molecular cloud simulations carried out with the moving mesh code arepo to explore nature star-forming filaments. The simulated filaments are identified and categorized from column density maps in same manner as for recent Herschel observations. When fitted Plummer-like profile, excellent agreement observations, have shallow power-law profiles p ∼ 2.2 without need magnetic support. data within 1 pc filament centre Gaussian function, average full width at...
Context: The past decade has witnessed a large number of Galactic plane surveys at angular resolutions below 20". However, no comparable high-resolution survey exists long radio wavelengths around 21cm in line and continuum emission. Methods: Employing the Very Large Array (VLA) C-array configuration program, we observe HI line, four OH lines, nineteen Halpha recombination lines as well emission from 1 to 2GHz full polarization over part first quadrant. Results: Covering longitudes 14.5...
The very long and thin infrared dark cloud "Nessie" is even longer than had been previously claimed, an analysis of its Galactic location suggests that it lies directly in the Milky Way's mid-plane, tracing out a highly elongated bone-like feature within prominent Scutum-Centaurus spiral arm. Re-analysis mid-infrared imagery from Spitzer Space Telescope shows this IRDC at least 2, possibly as many 5 times originally claimed by Nessie's discoverers (Jackson et al. 2010); aspect ratio...
We show that hydrodynamic turbulent cloud simulations naturally produce large filaments made up of a network smaller and coherent sub-filaments. Such resemble observations fibres in nearby molecular clouds. The sub-filaments are dynamical features formed at the stagnation points velocity field where shocks dissipate energy. They ubiquitous feature simulated clouds, which appear from beginning simulation not by gradual fragmentation larger filaments. Most gravitationally sub-critical do...
We introduce a new suite of simulations, "The Cloud Factory", which self-consistently forms molecular cloud complexes at high enough resolution to resolve internal substructure (up 0.25 Msol in mass) all while including galactic-scale forces. use version the Arepo code modified include detailed treatment physics cold ISM, and an analytical galactic gravitational potential for computational efficiency. The simulations have nested levels resolution, with lowest layer tied tracer particles...
We present here the first of a series papers aimed at better understanding evolution and properties giant molecular clouds (GMCs) in galactic context. perform high resolution, three-dimensional {\sc arepo} simulations an interacting galaxy inspired by well-observed M51 galaxy. Our fiducial include non-equilibrium, time-dependent, chemical network that follows atomic hydrogen as well carbon oxygen self-consistently. calculations also treat gas self-gravity subsequent star formation (described...
We present a high-resolution view of bubbles within The Phantom Galaxy (NGC 628); nearby (~10Mpc), star-forming (~2Msun/yr), face-on (i~9deg) grand-design spiral galaxy. With new data obtained as part the PHANGS-JWST treasury program, we perform detailed case-study two regions interest, one which contains largest and most prominent bubble in galaxy (The Void; over 1kpc diameter), other being smaller region that may be precursor to such large Precursor Void). When comparing matched resolution...
JWST observations of polycyclic aromatic hydrocarbon (PAH) emission provide some the deepest and highest resolution views cold interstellar medium (ISM) in nearby galaxies. If PAHs are well mixed with atomic molecular gas illuminated by average diffuse radiation field, PAH may an approximately linear, high resolution, sensitivity tracer surface density. We present a pilot study that explores using this way based on MIRI IC 5332, NGC 628, 1365, 7496 from PHANGS-JWST Treasury. Using scaling...
Abstract The earliest stages of star formation, when young stars are still deeply embedded in their natal clouds, represent a critical phase the matter cycle between gas clouds and stellar regions. Until now, high-resolution infrared observations required for characterizing this heavily obscured (during which massive have formed, but optical emission is not detected) could only be obtained handful most nearby galaxies. One main hurdles has been limited angular resolution Spitzer Space...
Abstract PHANGS–JWST mid-infrared (MIR) imaging of nearby spiral galaxies has revealed ubiquitous filaments dust emission in intricate detail. We present a pilot study to systematically map the filament network (DFN) at multiple scales between 25 and 400 pc NGC 628. MIRI images 7.7, 10, 11.3, 21 μ m 628 are used generate maps emission, while PHANGS–HST B -band yields attenuation features. quantify correspondence traced by MIR thermal continuum/polycyclic aromatic hydrocarbon (PAH) detected...
A saturated nickel-like samarium x-ray laser beam at 7 nanometers has been demonstrated with an output energy of 0.3 millijoule in 50-picosecond pulses, demonstrating that operation a wavelengths shorter than 10 can be achieved. The narrow divergence, short wavelength, pulse duration, high efficiency, and brightness this make it ideal candidate for many applications.
We introduce a prescription for the luminosity from accreting protostars into smoothed particle hydrodynamics simulation, and apply method to simulations of five primordial minihalos generated cosmological initial conditions. find that accretion delays fragmentation within halos, but does not prevent it. In halos slowly form low number protostars, can reduce fragments are formed before start ionising their surroundings. However, rapidly many become dominated by dynamical processes, effect...
We investigate the formation of both clustered and distributed populations young stars in a single molecular cloud. present numerical simulation 10,000 solar mass elongated, turbulent, cloud over 2500 stars. The form stellar clusters mode which is determined by local gravitational binding A density gradient along major axis produces bound regions that unbound more population. initial function also depends on with forming full IMFs whereas unbound, masses cluster around Jeans lack high-mass...
ABSTRACT We study the formation of galactic outflows from supernova (SN) explosions with moving-mesh code AREPO in a stratified column gas surface density similar to Milky Way disk at solar circle. compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), find that place SNe dense account CR diffusion are able drive mass loading as obtained random no CRs. Despite this similarity, CR-driven differ several other key properties their overall...
It has been known for more than 30 yr that the distribution of molecular gas in innermost 300 parsecs Milky Way, Central Molecular Zone, is strongly asymmetric. Indeed, approximately three quarters emission come from positive longitudes, and only one quarter negative longitudes. However, despite much theoretical effort, origin this asymmetry remained a mystery. Here, we show can be neatly explained by unsteady flow barred potential. We use high-resolution 3D hydrodynamical simulations...
We use hydrodynamical simulations to study the Milky Way's central molecular zone (CMZ). The include a non-equilibrium chemical network, gas self-gravity, star formation and supernova feedback. resolve structure of interstellar medium at sub-parsec resolution while also capturing interaction between CMZ bar-driven large-scale flow out $R\sim 5\kpc$. Our main findings are as follows: (1) distinction inner ($R\lesssim120$~pc) outer ($120\lesssim R\lesssim450$~pc) that is sometimes proposed in...