Daniel Seifried
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View article: Grain alignment and dust evolution physics with polarisation (GRADE-POL)
Grain alignment and dust evolution physics with polarisation (GRADE-POL) Open
The polarisation of light induced by aligned interstellar dust serves as a significant tool in investigating cosmic magnetic fields and dust properties, while posing a challenge in characterising the polarisation of the cosmic microwave ba…
View article: SILCC – IX. The multiphase interstellar medium at low metallicity
SILCC – IX. The multiphase interstellar medium at low metallicity Open
The gas-phase metallicity affects heating and cooling processes in the star-forming galactic interstellar medium (ISM) as well as ionizing luminosities, wind strengths, and lifetimes of massive stars. To investigate its impact, we conduct …
View article: On the origin of V-shaped polarization spectra in molecular clouds
On the origin of V-shaped polarization spectra in molecular clouds Open
We extend previous theoretical works to gain a better understanding of the origin of observed polarization degree spectra of molecular clouds, which show a so-called V-shape, i.e. a pronounced minimum around 350 $\mu$m. For this purpose, w…
View article: The HI-to-H2 transition in the Draco cloud
The HI-to-H2 transition in the Draco cloud Open
In recent decades, significant attention has been dedicated to analytical and observational studies of the atomic hydrogen (HI) to molecular hydrogen (H2) transition in the interstellar medium. We focussed on the Draco diffuse cloud to gai…
View article: The HI-to-H<sub>2</sub> transition in the Draco cloud
The HI-to-H<sub>2</sub> transition in the Draco cloud Open
In recent decades, significant attention has been dedicated to analytical and observational studies of the atomic hydrogen (H I ) to molecular hydrogen (H 2 ) transition in the interstellar medium. We focussed on the Draco diffuse cloud to…
View article: SILCC – VIII. The impact of far-ultraviolet radiation on star formation and the interstellar medium
SILCC – VIII. The impact of far-ultraviolet radiation on star formation and the interstellar medium Open
We present magnetohydrodynamic simulations of star formation in the multiphase interstellar medium (ISM) to quantify the impact of non-ionizing far-ultraviolet (FUV) radiation within the Silcc Project simulation framework. Our study incorp…
View article: The Molecular Cloud Life Cycle. I. Constraining H<sub>2</sub> Formation and Dissociation Rates with Observations
The Molecular Cloud Life Cycle. I. Constraining H<sub>2</sub> Formation and Dissociation Rates with Observations Open
Molecular clouds (MCs) are the birthplaces of new stars in galaxies. A key component of MCs are photodissociation regions (PDRs), where far-ultraviolet radiation plays a crucial role in determining the gas’s physical and chemical state. Tr…
View article: The impact of cosmic-ray heating on the cooling of the low-metallicity interstellar medium
The impact of cosmic-ray heating on the cooling of the low-metallicity interstellar medium Open
Low-metallicity environments are subject to inefficient cooling. They also have low dust-to-gas ratios and therefore less efficient photoelectric (PE) heating than in solar-neighbourhood conditions, where PE heating is one of the most impo…
View article: Emergence of high-mass stars in complex fiber networks (EMERGE)
Emergence of high-mass stars in complex fiber networks (EMERGE) Open
Context . Identified as parsec-size, gas clumps at the junction of multiple filaments, hub-filament systems (HFS) play a crucial role during the formation of young clusters and high-mass stars. These HFS still appear to be detached from mo…
View article: Emergence of high-mass stars in complex fiber networks (EMERGE) V. From filaments to spheroids: the origin of the hub-filament systems
Emergence of high-mass stars in complex fiber networks (EMERGE) V. From filaments to spheroids: the origin of the hub-filament systems Open
Identified as parsec-size, gas clumps at the junction of multiple filaments, hub-filament systems (HFS) play a crucial role during the formation of young clusters and high-mass stars. These HFS appear nevertheless to be detached from most …
View article: The Molecular Cloud Life Cycle. II. Formation and Destruction of Molecular Clouds Diagnosed via H<sub>2</sub> Fluorescent Emission
The Molecular Cloud Life Cycle. II. Formation and Destruction of Molecular Clouds Diagnosed via H<sub>2</sub> Fluorescent Emission Open
Molecular hydrogen (H 2 ) formation and dissociation are key processes that drive the gas life cycle in galaxies. Using the SImulating the LifeCycle of Molecular Clouds zoom-in simulation suite, we explore the utility of future observation…
View article: The impact of cosmic ray heating on the cooling of the low-metallicity interstellar medium
The impact of cosmic ray heating on the cooling of the low-metallicity interstellar medium Open
Low-metallicity environments are subject to inefficient cooling. They also have low dust-to-gas ratios and therefore less efficient photoelectric (PE) heating than in solar-neighbourhood conditions, where PE heating is one of the most impo…
View article: The origin and evolution of the [CII] deficit in HII regions and star-forming molecular clouds
The origin and evolution of the [CII] deficit in HII regions and star-forming molecular clouds Open
We analyse synthetic maps of the [CII] 158 $μ$m line and FIR continuum of simulated molecular clouds (MCs) within the SILCC-Zoom project to study the origin of the [CII] deficit, i.e., the drop in the [CII]/FIR intensity ratio. All simulat…
View article: SILCC -- VIII: The impact of far-ultraviolet radiation on star formation and the interstellar medium
SILCC -- VIII: The impact of far-ultraviolet radiation on star formation and the interstellar medium Open
We present magnetohydrodynamic simulations of star formation in the multiphase interstellar medium to quantify the impact of non-ionising far-ultraviolet (FUV) radiation within the \textsc{Silcc Project} simulation framework. Our study inc…
View article: The Molecular Cloud Lifecycle I: Constraining H2 formation and dissociation rates with observations
The Molecular Cloud Lifecycle I: Constraining H2 formation and dissociation rates with observations Open
Molecular clouds (MCs) are the birthplaces of new stars in galaxies. A key component of MCs are photodissociation regions (PDRs), where far-ultraviolet radiation plays a crucial role in determining the gas's physical and chemical state. Tr…
View article: HYACINTH: HYdrogen And Carbon chemistry in the INTerstellar medium in Hydro simulations
HYACINTH: HYdrogen And Carbon chemistry in the INTerstellar medium in Hydro simulations Open
Aims . We present a new sub-grid model, HYACINTH – HYdrogen And Carbon chemistry in the INTerstellar medium in Hydro simulations – for computing the non-equilibrium abundances of H 2 and its carbon-based tracers, namely CO, C, and C + , in…
View article: Properties of molecular clumps and cores in colliding magnetized flows
Properties of molecular clumps and cores in colliding magnetized flows Open
We simulate the formation of molecular clouds in colliding flows of warm neutral medium with the adaptive mesh refinement code flash in eight simulations with varying initial magnetic field strength, between 0.01–5 μG. We include a chemica…
View article: On the evolution of the observed mass-to-length relationship for star-forming filaments
On the evolution of the observed mass-to-length relationship for star-forming filaments Open
The interstellar medium is threaded by a hierarchy of filaments from large scales (∼100 pc) to small scales (∼0.1 pc). The masses and lengths of these nested structures may reveal important constraints for cloud formation and evolution, bu…
View article: The Molecular Cloud Lifecycle II: Formation and Destruction of Molecular Clouds Diagnosed via H$_2$ Fluorescent Emission Emission
The Molecular Cloud Lifecycle II: Formation and Destruction of Molecular Clouds Diagnosed via H$_2$ Fluorescent Emission Emission Open
Molecular hydrogen (H$_2$) formation and dissociation are key processes that drive the gas lifecycle in galaxies. Using the SImulating the LifeCycle of Molecular Clouds (SILCC) zoom-in simulation suite, we explore the utility of future obs…
View article: SILCC-Zoom: the dynamic balance in molecular cloud substructures
SILCC-Zoom: the dynamic balance in molecular cloud substructures Open
How molecular clouds fragment into dense structures that eventually form stars is an open question. We investigate the relative importance of gravity (both self-gravity and tidal forces) and the volume and surface terms of kinetic, thermal…
View article: On the origin of V-shaped polarisation spectra in molecular clouds
On the origin of V-shaped polarisation spectra in molecular clouds Open
We extend previous theoretical works to gain a better understanding of the origin of observed polarisation degree spectra of molecular clouds, which show a so-called V-shape, i.e. a pronounced minimum around 350~$μ$m. For this purpose, we …
View article: CO and [C <scp>ii</scp>] line emission of molecular clouds: the impact of stellar feedback and non-equilibrium chemistry
CO and [C <span>ii</span>] line emission of molecular clouds: the impact of stellar feedback and non-equilibrium chemistry Open
We analyse synthetic 12CO, 13CO, and [C ii] emission maps of molecular cloud (MC) simulations from the SILCC-Zoom project. We present radiation, magnetohydrodynamic zoom-in simulations of individual clouds, both with and without radiative …
View article: Unravelling the structure of magnetised molecular clouds with SILCC-Zoom: sheets, filaments and fragmentation
Unravelling the structure of magnetised molecular clouds with SILCC-Zoom: sheets, filaments and fragmentation Open
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 the SILCC-Zoom simulations. These simulations follow the s…
View article: Unravelling the structure of magnetized molecular clouds with SILCC-Zoom: sheets, filaments, and fragmentation
Unravelling the structure of magnetized molecular clouds with SILCC-Zoom: sheets, filaments, and fragmentation Open
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 the SILCC-Zoom simulations. These simulations follow the s…
View article: The evolution of HCO+ in molecular clouds using a novel chemical post-processing algorithm
The evolution of HCO+ in molecular clouds using a novel chemical post-processing algorithm Open
Modelling the chemistry of molecular clouds is critical to accurately simulating their evolution. To reduce computational cost, 3D simulations generally restrict their chemistry to species with strong heating and cooling effects. Time-depe…
View article: How do supernova remnants cool? – I. Morphology, optical emission lines, and shocks
How do supernova remnants cool? – I. Morphology, optical emission lines, and shocks Open
Supernovae (SNe) inject ∼1051 erg in the interstellar medium, thereby shocking and heating the gas. A substantial fraction of this energy is later lost via radiative cooling. We present a post-processing module for the flash code to calcul…
View article: How do supernova remnants cool? -- I. Morphology, optical emission lines, and shocks
How do supernova remnants cool? -- I. Morphology, optical emission lines, and shocks Open
Supernovae (SNe) inject $\sim 10^{51}$ erg in the interstellar medium, thereby shocking and heating the gas. A substantial fraction of this energy is later lost via radiative cooling. We present a post-processing module for the FLASH code …
View article: SILCC – VII. Gas kinematics and multiphase outflows of the simulated ISM at high gas surface densities
SILCC – VII. Gas kinematics and multiphase outflows of the simulated ISM at high gas surface densities Open
We present magnetohydrodynamic (MHD) simulations of the star-forming multiphase interstellar medium (ISM) in stratified galactic patches with gas surface densities Σgas = 10, 30, 50, and 100 $\mathrm{M_\odot \, pc^{-2}}$. The silcc project…
View article: 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
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 Open
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 radiative transfer of diffuse sources via backwards ray tr…
View article: Hyperion: the origin of the stars. A far UV space telescope for high-resolution spectroscopy over wide fields
Hyperion: the origin of the stars. A far UV space telescope for high-resolution spectroscopy over wide fields Open
We present Hyperion, a mission concept recently proposed to the December 2021 NASA Medium Explorer announcement of opportunity. Hyperion explores the formation and destruction of molecular clouds and planet-forming disks in nearby star-for…