Publications (63)
Tree-based solvers for adaptive mesh refinement code FLASH -- III: a novel scheme for radiation pressure on dust and gas and radiative transfer from diffuse sources
A. Klepitko, S. Walch, R. Wünsch +3
Radiation is an important contributor to the energetics of the interstellar medium, yet its transport is difficult to solve numerically. We present a novel approach towards solving…
SILCC-Zoom: H and CO-dark gas in molecular clouds -- The impact of feedback and magnetic fields
D. Seifried, S. Haid, S. Walch +2
We analyse the CO-dark molecular gas content of simulated molecular clouds from the SILCC-Zoom project. The simulations reach a resolution of 0.1 pc and include H and CO format…
Protostellar discs formed from turbulent cores
S. Walch, T. Naab, A. Burkert +2
We investigate the collapse and fragmentation of low-mass, trans-sonically turbulent prestellar cores, using SPH simulations. The initial conditions are slightly supercritical Bonn…
ALMAGAL III. Compact source catalog: Fragmentation statistics and physical evolution of the core population
A. Coletta, S. Molinari, E. Schisano +49
The mechanisms behind the fragmentation of high-mass dense clumps into compact star-forming cores are fundamental topics in current astrophysical research. The ALMAGAL survey provi…
Revealing the dynamics of Class 0 protostellar discs with ALMA
D. Seifried, Ã. Sánchez-Monge, S. Walch +1
We present synthetic ALMA observations of Keplerian, protostellar discs in the Class 0 stage studying the emission of molecular tracers like CO, CO, HCO, H…
Dynamical Accretion Flows -- ALMAGAL: Flows along filamentary structures in high-mass star-forming clusters
M. R. A. Wells, H. Beuther, S. Molinari +47
We use data from the ALMA Evolutionary Study of High Mass Protocluster Formation in the Galaxy (ALMAGAL) survey to study 100 ALMAGAL regions at 1 arsecond resolution located…
Modelling the supernova-driven ISM in different environments
A. Gatto, S. Walch, M. -M. Mac Low +11
We use hydrodynamical simulations in a periodic box to model the impact of supernova (SN) explosions on the multi-phase interstellar medium (ISM) for initial de…
Synthetic [CII] emission maps of a simulated molecular cloud in formation
A. Franeck, S. Walch, D. Seifried +10
The C ion is an important coolant of interstellar gas, and so the [CII] fine structure line is frequently observed in the interstellar medium. However, the physical and chemi…
Synthetic CO observations of fibrous filaments: the problems of mapping from PPV to PPP
S. D. Clarke, A. P. Whitworth, R. L. Spowage +5
Molecular-line observations of filaments in star-forming regions have revealed the existence of elongated coherent features within the filaments; these features are termed fibres.…
Clumps and triggered star formation in ionised molecular clouds
S. Walch, A. P. Whitworth, T. G. Bisbas +2
Infrared shells and bubbles are ubiquitous in the Galaxy and can generally be associated with HII regions formed around young, massive stars. In this paper, we use high-resolution…
GMF G214.5-1.8 as traced by CO: I -- cloud-scale CO freeze-out as a result of a low cosmic-ray ionisation rate
S. D. Clarke, V. A. Makeev, Ã. Sánchez-Monge +6
We present an analysis of the outer Galaxy giant molecular filament (GMF) G214.5-1.8 (G214.5) using IRAM 30m data of CO, CO and CO. We find that the CO…
Algorithmic comparisons of decaying, isothermal, supersonic turbulence
S. Kitsionas, C. Federrath, R. Klessen +10
Contradicting results have been reported in the literature with respect to the performance of the numerical techniques employed for the study of supersonic turbulence. We aim at ch…
Simulating star formation in Ophiuchus
O. Lomax, A. P. Whitworth, D. A. Hubber +2
We have simulated star formation in prestellar cores, using SPH and initial conditions informed by observations of the cores in Ophiuchus. Because the observations are limited to t…
Comparing simulations of ionisation triggered star formation and observations in RCW 120
S. Walch, A. Whitworth, T. Bisbas +2
Massive clumps within the swept-up shells of bubbles, like that surrounding the galactic HII region RCW 120, have been interpreted in terms of the Collect and Collapse (C&C) mechan…
The SILCC project: III. Regulation of star formation and outflows by stellar winds and supernovae
A. Gatto, S. Walch, T. Naab +9
We study the impact of stellar winds and supernovae on the multi-phase interstellar medium using three-dimensional hydrodynamical simulations carried out with FLASH. The selected g…
On the resolution requirements for modelling molecular gas formation in solar neighbourhood conditions
P. R. Joshi, S. Walch, D. Seifried +3
The formation of molecular hydrogen (H) and carbon monoxide (CO) is sensitive to the volume and column density distribution of the turbulent interstellar medium. In this paper,…
Radiation Driven Implosion and Triggered Star Formation
T. G. Bisbas, A. P. Whitworth, R. Wünsch +2
We present simulations of initially stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to radiatively dri…
StarBench: The D-type expansion of an HII region
T. G. Bisbas, T. J. Haworth, R. J. R. Williams +16
StarBench is a project focused on benchmarking and validating different star-formation and stellar feedback codes. In this first StarBench paper we perform a comparison study of th…
HyGAL: Characterizing the Galactic ISM with observations of hydrides and other small molecules II. The absorption line survey with the IRAM 30 m telescope
W. -J. Kim, P. Schilke, D. A. Neufeld +11
As a complement to the HyGAL Stratospheric Observatory for Infrared Astronomy Legacy Program, we report the results of a ground-based absorption line survey of simple molecules in…
Protostellar disks formed from rigidly rotating cores
S. Walch, A. Burkert, A. Whitworth +2
Abridged: We use three-dimensional SPH simulations to investigate the collapse of low-mass prestellar cores and the formation and early evolution of protostellar discs. The initial…
HyGAL: Characterizing the Galactic ISM with observations of hydrides and other small molecules -- I. Survey description and a first look toward W3(OH), W3 IRS5 and NGC 7538 IRS1
A. M. Jacob, D. A. Neufeld, P. Schilke +22
The HyGAL SOFIA legacy program surveys six hydride molecules -- ArH+, OH+, H2O+, SH, OH, and CH -- and two atomic constituents -- C+ and O -- within the diffuse interstellar medium…
Supernova 2006aj and the associated X-Ray Flash 060218
J. Sollerman, A. O. Jaunsen, J. P. U. Fynbo +23
We have studied the afterglow of the gamma-ray burst (GRB) of February 18, 2006. This is a nearby long GRB, with a very low peak energy, and is therefore classified as an X-ray Fla…
ALMAGAL VI. The spatial distribution of dense cores during the evolution of cluster-forming massive clump
E. Schisano, S. Molinari, A. Coletta +51
High-mass stars and star clusters form from the fragmentation of massive dense clumps driven by gravity, turbulence, and magnetic fields. The ALMAGAL project observed cl…
From parallel to perpendicular -- On the orientation of magnetic fields in molecular clouds
D. Seifried, S. Walch, M. Weis +4
We present synthetic dust polarization maps of simulated molecular clouds (MCs) with the goal to systematically explore the origin of the relative orientation of the magnetic field…
ALMAGAL IV. Morphological comparison of molecular and thermal dust emission using the histogram of oriented gradients (HOG) method
C. Mininni, S. Molinari, J. D. Soler +46
The study of molecular line emission is crucial to unveil the kinematics and the physical conditions of gas in star-forming regions. Our aim is to quantify the reliability of using…
SILCC-Zoom: Polarisation and depolarisation in molecular clouds
D. Seifried, S. Walch, S. Reissl +1
We present synthetic dust polarisation maps of 3D magneto-hydrodynamical simulations of molecular clouds before the onset of stellar feedback. The clouds are modelled within the SI…
Probing 3D Density and Velocity Fields of ISM in Centers of Galaxies with Future X-Ray Observations
E. Churazov, I. Khabibullin, R. Sunyaev +4
Observations of bright and variable "reflected" X-ray emission from molecular clouds located within inner hundred parsec of our Galaxy have demonstrated that the central supermassi…
X-raying molecular clouds with a short flare: probing statistics of gas density and velocity fields
I. Khabibullin, E. Churazov, R. Sunyaev +3
We take advantage of a set of molecular cloud simulations to demonstrate a possibility to uncover statistical properties of the gas density and velocity fields using reflected emis…
Understanding the spectra of isolated Herbig stars in the frame of a passive disk model
C. Dominik, C. P. Dullemond, L. B. F. M. Waters +1
We discuss spectral energy distributions of a sample of Herbig Ae/Be stars in the context of a passive irradiated disk model. The data have been presented earlier by Meeus et al (2…
The influence of the turbulent perturbation scale on prestellar core fragmentation and disk formation
S. Walch, A. P. Whitworth, P. Girichidis
The collapse of weakly turbulent prestellar cores is a critical stage in the process of star formation. Being highly non-linear and stochastic, the outcome of collapse can only be…
ALMAGAL IX. The chemical complexity of AG318.9477-00.1960: A line-identification template for ALMAGAL
J. Allande, M. T. Beltrán, V. M. Rivilla +36
We present a detailed molecular line analysis of one of the most chemically rich cores in the ALMAGAL sample, the high-mass core~9 in the AG318.9477-00.1960 clump (AG318-c9), locat…
The impact of episodic outflow feedback on stellar multiplicity and the star formation efficiency
P. F. Rohde, S. Walch, S. D. Clarke +3
The accretion of material onto young protostars is accompanied by the launching of outflows. Observations show that accretion, and therefore also outflows, are episodic. However, t…
Unveiling the corona of the Milky Way via ram-pressure stripping of dwarf satellites
A. Gatto, F. Fraternali, J. I. Read +3
The spatial segregation between dSphs and dIrrs in the Local Group has long been regarded as evidence of an interaction with their host galaxies. In this paper, we assume that ram-…
ALMAGAL I. The ALMA evolutionary study of high-mass protocluster formation in the Galaxy. Presentation of the survey and early results
S. Molinari, P. Schilke, C. Battersby +73
Fundamental questions about the physics responsible for fragmenting molecular parsec-scale clumps into cores of ~1000 au are still open, that only a statistically significant inves…
Simulations of star formation in Ophiuchus, II: Multiplicity
O. Lomax, A. P. Whitworth, D. A. Hubber +2
Lomax et al. have constructed an ensemble of 60 prestellar cores having masses, sizes, projected shapes, temperatures and non-thermal radial velocity dispersions that match, statis…
Modelling the chemistry of star forming filaments - H and CO chemistry
D. Seifried, S. Walch
We present simulations of star forming filaments incorporating on of the largest chemical network used to date on-the-fly in a 3D-MHD simulation. The network contains 37 chemical s…
Determining the presence of characteristic fragmentation length-scales in filaments
S. D. Clarke, G. M. Williams, J. C. Ibáñez-MejÃa +1
Theories suggest that filament fragmentation should occur on a characteristic fragmentation length-scale. This fragmentation length-scale can be related to filament properties, suc…
SILCC-Zoom: The dynamical and chemical evolution of molecular clouds
D. Seifried, S. Walch, P. Girichidis +6
We present 3D "zoom-in" simulations of the formation of two molecular clouds out of the galactic interstellar medium. We model the clouds - identified from the SILCC simulations -…
On the accuracy of HI observations in molecular clouds -- More cold HI than thought?
D. Seifried, H. Beuther, S. Walch +4
We present a study of the cold atomic hydrogen (HI) content of molecular clouds simulated within the SILCC-Zoom project. We produce synthetic observations of HI at 21 cm including…
Crystalline silicates as a probe of disk formation history
C. P. Dullemond, D. Apai, S. Walch
We present a new perspective on the crystallinity of dust in protoplanetary disks. The dominant crystallization by thermal annealing happens in the very early phases of disk format…
CO and [CII] line emission of molecular clouds -- the impact of stellar feedback and non-equilibrium chemistry
S. Ebagezio, D. Seifried, S. Walch +3
We analyse synthetic CO, CO, and [CII] emission maps of simulated molecular clouds of the SILCC-Zoom project, which include an on-the-fly evolution of H, CO, and…
Simulated [CII] in high-z galaxies
N. Muñoz-Elgueta, F. Arrigoni Battaia, G. Kauffmann +4
Extended [CII] emission on tens of kpc, also known as a [CII] halo, is being currently reported around z4-6 star-forming galaxies, especially thanks to the statistics of the…
A Herschel study of G214.5-1.8: a young, cold and quiescent giant molecular filament on the shell of a HI superbubble
S. D. Clarke, A. Sanchez-Monge, G. M. Williams +3
We present an analysis of the outer Galaxy giant molecular filament (GMF) G214.5-1.8 (G214.5) using Herschel data. We find that G214.5 has a mass of 16,000 M, yet…
Dispersal of molecular clouds by ionising radiation
S. Walch, A. P. Whitworth, T. Bisbas +2
The role of feedback from massive stars is believed to be a key element in the evolution of molecular clouds. We use high-resolution 3D SPH simulations to explore the dynamical eff…
iVINE - Ionization in the parallel tree/SPH code VINE: First results on the observed age-spread around O-stars
M. Gritschneder, T. Naab, A. Burkert +3
We present a three-dimensional, fully parallelized, efficient implementation of ionizing UV radiation for smoothed particle hydrodynamics (SPH) including self-gravity. Our method i…
Protostellar Outflows: a window to the past
P. F. Rohde, S. Walch, D. Seifried +2
During the early phases of low-mass star formation, episodic accretion causes the ejection of high-velocity outflow bullets, which carry a fossil record of the driving protostar's…
Modelling the chemical evolution of star forming filaments
D. Seifried, S. Walch
We present simulations of star forming filaments incorporating - to our knowledge - the largest chemical network used to date on-the-fly in a 3D-MHD simulation. The network contain…
The hierarchical fragmentation of filaments and the role of sub-filaments
S. D. Clarke, G. M. Williams, S. Walch
Recent observations have revealed the presence of small fibres or sub-filaments within larger filaments. We present a numerical fragmentation study of fibrous filaments investigati…
An improved sink particle algorithm for SPH simulations
D. A. Hubber, S. Walch, A. P. Whitworth
Numerical simulations of star formation frequently rely on the implementation of sink particles, (a) to avoid expending computational resource on the detailed internal physics of i…
ALMAGAL II. The ALMA evolutionary study of high-mass protocluster formation in the Galaxy. ALMA data processing and pipeline
Ã. Sánchez-Monge, C. L. Brogan, T. R. Hunter +53
The ALMAGAL Large Program has observed 1017 high-mass star-forming regions distributed throughout the Galaxy, sampling different evolutionary stages and environmental conditions. I…
ALMAGAL VIII. Early phases of triggered star formation in source AG286.07161.8229
C. Mininni, S. Molinari, W. J. Kim +50
Several theoretical and observational studies have shown that new waves of triggered star-formation can be induced by the feedback from newly formed massive protostars, due to the…
Evolution of Hubble wedges in episodic protostellar outflows
P. F. Rohde, S. Walch, D. Seifried +2
Young low-mass protostars undergo short phases of high accretion and outburst activity leading to lumpy outflows. Recent observations have shown that the position-velocity and mass…
The impact of turbulence and magnetic field orientation on star forming filaments
D. Seifried, S. Walch
We present simulations of collapsing filaments studying the impact of turbulence and magnetic field morphologies on their evolution and star formation properties. We vary the mass…
How do supernova remnants cool? II. Machine learning analysis of supernova remnant simulations
P. Smirnova, E. I. Makarenko, S. D. Clarke +4
About 15%-60% of all supernova remnants are estimated to interact with dense molecular clouds. In these high density environments, radiative losses are significant. The cooling rad…
Unravelling the structure of magnetised molecular clouds with SILCC-Zoom: sheets, filaments and fragmentation
S. Ganguly, S. Walch, D. Seifried +2
To what extent magnetic fields affect how molecular clouds (MCs) fragment and create dense structures is an open question. We present a numerical study of cloud fragmentation using…
SILCC-Zoom: the dynamic balance in molecular cloud substructures
S. Ganguly, S. Walch, S. D. Clarke +1
How molecular clouds fragment and create the dense structures which go on to form stars is an open question. We investigate the relative importance of different energy terms (kinet…
ALMAGAL V. Relations between the core populations and the parent clump physical properties
D. Elia, A. Coletta, S. Molinari +54
Context. The fragmentation of massive molecular clumps into smaller, potentially star-forming cores plays a key role in the processes of high-mass star formation. The ALMAGAL proje…
Modelling the chemistry of star-forming filaments - II. Testing filament characteristics with synthetic observations
D. Seifried, Ã. Sánchez-Monge, S. Suri +1
We present synthetic continuum and CO and CO line emission observations of dense and cold filaments. The filaments are dynamically evolved using 3D-MHD simulations th…
The evolution of HCO in molecular clouds using a novel chemical post-processing algorithm
M. Panessa, D. Seifried, S. Walch +4
Modeling the chemistry of molecular clouds is critical to accurately simulating their evolution. To reduce computational cost, 3D simulations generally restrict their chemistry to…
Soft X-ray absorption excess in gamma-ray burst afterglow spectra: Absorption by turbulent ISM
M. Tanga, P. Schady, A. Gatto +5
Two-thirds of long duration gamma-ray bursts (GRBs) show soft X-ray absorption in excess of the Milky Way. The column densities of metals inferred from UV and optical spectra diffe…
How fast do young star clusters expel their natal gas?: Estimating the upper limit of the gas expulsion time-scale
F. Dinnbier, S. Walch
Formation of massive stars within embedded star clusters starts a complex interplay between their feedback, inflowing gas and stellar dynamics, which often includes close stellar e…
Is molecular cloud turbulence driven by external supernova explosions?
D. Seifried, S. Walch, S. Haid +2
We present high-resolution ( 0.1 pc), hydrodynamical and magnetohydrodynamical simulations to investigate whether the observed level of molecular cloud (MC) turbulence can be…
The turbulent fragmentation of the interstellar medium: The impact of metallicity on global star formation
S. Walch, R. Wuensch, A. Burkert +2
We study the influence of gas metallicity, turbulence, and non-equilibrium chemistry on the evolution of the two-phase interstellar medium (warm and cold atomic phases), and thereb…