Article
Astronomy & Astrophysics
David J. Whitworth, Rowan J. Smith, Ralf S. Klessen, Mordecai-Mark Mac Low, Simon C. O. Glover, Robin Tress, Ruediger Pakmor, Juan D. Soler
Summary: Many studies have shown that magnetic fields can suppress star formation in molecular clouds and Milky Way like galaxies. However, most of these studies have focused on fully developed fields at saturation level, and there is little understanding of how weak initial primordial fields affect star formation in low metallicity environments. In this paper, the impact of a weak initial field on low metallicity dwarf galaxies is investigated. High-resolution AREPO simulations are performed, and the results show that the magnetic field has little impact on the global star formation rate (SFR), contrary to some previous studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Anathpindika, J. Di Francesco
Summary: This study explores the formation of prestellar cores and reveals that cores formed under different pressures exhibit distinct shapes, as well as the relationship between velocity gradient variations and filament evolution.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
David J. Whitworth, Rowan J. Smith, Robin Tress, Scott T. Kay, Simon C. O. Glover, Mattia C. Sormani, Ralf S. Klessen
Summary: This paper investigates the impact of metallicity and ultraviolet (UV) field strength on star formation and the molecular gas Kennicutt-Schmidt (KS) relation within a galaxy. By conducting simulations of isolated dwarf galaxies, the authors find that reducing metallicity and UV field has minimal effect on star formation but moderately steepens the KS relation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Indrani Das, Shantanu Basu
Summary: We have developed a semi-analytical formalism to determine the evolution of the stellar mass accretion rate for specified density and velocity profiles resulting from the runaway collapse of a prestellar cloud core. Our model combines the dominant spherical envelope accretion in the early phase with the important disc accretion in the later phase, accounting for episodic accretion bursts at appropriate times.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Robin G. Tress, Mattia C. Sormani, Rowan J. Smith, Simon C. O. Glover, Ralf S. Klessen, Mordecai-Mark Mac Low, Paul Clark, Ana Duarte-Cabral
Summary: This study investigates the reactions of giant molecular clouds to different environmental conditions in galaxies, revealing that galaxy interactions or isolation have limited effects on cloud masses and sizes, but can promote the formation of counter-rotating clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Glen H. Hunter, Paul C. Clark, Simon C. O. Glover, Ralf S. Klessen
Summary: In this study, the impact of collision speed, magnetic field inclination, and resolution on the star formation rate (SFR) in cloud-cloud collisions is investigated. A factor of 2-3 increase in the SFR is found compared to no collision simulations, with high collisional velocities, parallel magnetic field and collision axis orientation, and lower resolution leading to earlier star formation. The alignment of velocity and magnetic field is consistent in low-density environments but becomes more perpendicular as density increases, indicating the compression of the magnetic field by collapsing gas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. D. Clarke, S. E. Jaffa, A. P. Whitworth
Summary: This study presents an improved automated morphological classification technique called RJ-plots, which allows for clearer distinctions between different morphologies of the interstellar medium. It also reveals a strong correlation between the central concentration of a structure and its star formation efficiency and dense gas fraction.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. D. Priestley, A. P. Whitworth
Summary: The widths of filamentary structures in molecular clouds observed in far-infrared observations are closely related to the location of the accretion shock. Higher Mach numbers result in narrower filaments, consistent with the observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Luca Olmi, J. Brand, D. Elia
Summary: Observations were made with ALMA of starless and protostellar clumps, revealing multiple cores and varying morphologies. The results suggest a correlation between high core formation efficiency and parent clumps that convert a larger fraction of their initial mass into a single or a few cores.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Wienen, C. M. Brunt, C. L. Dobbs, D. Colombo
Summary: Expanding (sub)millimetre capabilities to high angular resolution with interferometers enables the resolution of giant molecular clouds in nearby galaxies. By remapping CO-C-12 data along the Perseus spiral arm in the Milky Way, at a common distance to an observer outside the galaxy, important insights into the structure of the arm, including thickness, centroid position, and mass distribution, were determined.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
J. Kainulainen, S. Rezaei Kh, A. Spilker, J. Orkisz
Summary: The Gaia data provides an unprecedented view of the 3D structure of molecular clouds near the Sun. Viewing angle affects the observed areas and masses of individual clouds, with joint probability distributions showing strong correlation and multiple peaks. Despite viewing angle effects, the overall KS relation of the sample is relatively stable due to covariance between areas and masses.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. T. Barnes, J. Liu, Q. Zhang, J. C. Tan, F. Bigiel, P. Caselli, G. Cosentino, F. Fontani, J. D. Henshaw, I. Jimenez-Serra, D. -S. Kalb, C. Y. Law, S. N. Longmore, R. J. Parker, J. E. Pineda, A. Sanchez-Monge, W. Lim, K. Wang
Summary: New high-angular-resolution observations have revealed the existence of a massive, starless core, which has implications for theories of massive star formation.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
F. Fontani, A. Schmiedeke, A. Sanchez-Monge, L. Colzi, D. Elia, V. M. Rivilla, M. T. Beltran, L. Bizzocchi, P. Caselli, L. Magrini, D. Romano
Summary: The study reveals that the chemical properties of the outer star-forming regions of the Galaxy are similar to those of the inner and local regions. Methanol (CH3OH) is detected in the observed targets, and its emission is associated with an extended envelope, indicating that it mainly comes from a cold and quiescent region. The relative abundance of CH3OH shows good correlations with that of H2CO, but not with HCO. These findings have significant implications for understanding the organic and possibly pre-biotic chemistry in the outermost star-forming regions of the Galaxy.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
F. D. Priestley, P. C. Clark, S. C. O. Glover, S. E. Ragan, O. Feher, L. R. Prole, R. S. Klessen
Summary: The study finds that molecular species commonly assumed to trace the dense, star-forming component of molecular clouds actually exist in material transiently enhanced in density. Only N2H+ exists in detectable quantities above a certain volume density, and N2H+ emission can be used to predict star formation in molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ahmad A. Ali, Thomas J. R. Bending, Clare L. Dobbs
Summary: The role of different stellar feedback mechanisms in giant molecular clouds, especially in regions with interacting clouds in galactic spiral arms, is investigated. A 500 pc x 500 pc x 100 pc section of a spiral arm is extracted from a galaxy simulation and re-simulated using smoothed particle hydrodynamics at higher resolution. The study finds that photoionization dominates the disruption of the spiral arm, while stellar winds only create small cavities. Stellar winds have a negligible impact on cloud statistics and the integrated star formation rate/efficiency, unlike photoionization which produces more stars and higher density, higher velocity dispersion clouds. Stellar winds also affect the properties of cluster-sink particles, distributing star formation among more low-mass sinks and producing fewer high-mass sinks.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Christine M. Simpson, Ruediger Pakmor, Christoph Pfrommer, Simon C. O. Glover, Rowan Smith
Summary: In this study, the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) is explored under varying assumptions of supernova explosion environment. It is found that CR pressure and transport are important factors that strongly influence the ISM's solution state. Observable signatures such as gamma-ray emission and H i gas are also investigated, with the gamma-ray luminosity being consistent with observations but the thickness of the H i gas layer potentially being too compact.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
David J. Whitworth, Rowan J. Smith, Ralf S. Klessen, Mordecai-Mark Mac Low, Simon C. O. Glover, Robin Tress, Ruediger Pakmor, Juan D. Soler
Summary: Many studies have shown that magnetic fields can suppress star formation in molecular clouds and Milky Way like galaxies. However, most of these studies have focused on fully developed fields at saturation level, and there is little understanding of how weak initial primordial fields affect star formation in low metallicity environments. In this paper, the impact of a weak initial field on low metallicity dwarf galaxies is investigated. High-resolution AREPO simulations are performed, and the results show that the magnetic field has little impact on the global star formation rate (SFR), contrary to some previous studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Lukas Eisert, Annalisa Pillepich, Dylan Nelson, Ralf S. Klessen, Marc Huertas-Company, Vicente Rodriguez-Gomez
Summary: By using machine learning techniques, we can infer the unobservable stellar assembly and merger history of central galaxies from their observable properties. This is a crucial first step towards empirical studies of galaxy evolution enriched by cosmological simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Li-Hsin Chen, Annalisa Pillepich, Simon C. O. Glover, Ralf S. Klessen
Summary: We analysed the location of extremely metal-poor stars (EMPs) in 198 Milky Way/M31-like galaxies in the TNG50 simulation. According to the simulation, the stellar halo of the main galaxy and satellites have the highest frequency of EMPs and are more likely to find them, with lower-mass satellites having a higher frequency. The majority of EMPs in the system are predicted to be hosted by the stellar halo of the main galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
R. Riaz, D. R. G. Schleicher, S. Bovino, S. Vanaverbeke, Ralf S. Klessen
Summary: The study investigates the impact of collision-induced emission (CIE) cooling on the formation and accretion of metal-free binaries. It finds that CIE cooling significantly affects the formation and mass accumulation processes of intermediate-mass binaries and most massive protobinaries (MMPBs).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Traficante, B. M. Jones, A. Avison, G. A. Fuller, M. Benedettini, D. Elia, S. Molinari, N. Peretto, S. Pezzuto, T. Pillai, K. L. J. Rygl, E. Schisano, R. J. Smith
Summary: The mechanism of the formation of the most massive stars is still not completely understood. The SQUALO project, an ALMA survey, was introduced to investigate the properties of 13 massive clumps in different evolutionary stages. The results obtained from the survey show evidence of fragmentation and correlation between the physical properties of the fragments and their parent clumps.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Glen H. Hunter, Paul C. Clark, Simon C. O. Glover, Ralf S. Klessen
Summary: In this study, the impact of collision speed, magnetic field inclination, and resolution on the star formation rate (SFR) in cloud-cloud collisions is investigated. A factor of 2-3 increase in the SFR is found compared to no collision simulations, with high collisional velocities, parallel magnetic field and collision axis orientation, and lower resolution leading to earlier star formation. The alignment of velocity and magnetic field is consistent in low-density environments but becomes more perpendicular as density increases, indicating the compression of the magnetic field by collapsing gas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Lewis R. Prole, Anna T. P. Schauer, Paul C. Clark, Simon C. O. Glover, Felix D. Priestley, Ralf S. Klessen
Summary: Molecular hydrogen allows the primordial gas to cool and collapse into Population III stars. The Lyman-Werner radiation from these stars can destroy H-2 in other halos and delay further star formation. The study of selected halos shows that the IMF for masses above the brown dwarf limit is not significantly affected by the background Lyman-Werner field strength, indicating that the IMF for Pop III.2 stars is similar to the initial population of Pop III.1 stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Shuo Kong, Volker Ossenkopf-Okada, Hector G. Arce, Ralf S. Klessen, Duo Xu
Summary: In this paper, a pilot parameter exploration for the collision-induced magnetic reconnection (CMR) mechanism that forms filamentary molecular clouds is conducted. The authors utilized Athena++ to simulate CMR in the context of resistive magnetohydrodynamics (MHD) and considered the effect of seven physical conditions on the formation of CMR. The exploration results reveal straight and curved CMR filaments with rich substructures that are highly variable in space and time, reflecting the chaotic nature of magnetic reconnection in CMR. The exploration provides useful initial insights into the CMR mechanism.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
Fabian Scheuermann, Kathryn Kreckel, Ashley T. Barnes, Francesco Belfiore, Brent Groves, Stephen Hannon, Janice C. Lee, Rebecca Minsley, Erik Rosolowsky, Frank Bigiel, Guillermo A. Blanc, Mederic Boquien, Daniel A. Dale, Sinan Deger, Oleg Egorov, Eric Emsellem, Simon C. O. Glover, Kathryn Grasha, Hamid Hassani, Sarah M. R. Jeffreson, Ralf S. Klessen, J. M. Diederik Kruijssen, Kirsten L. Larson, Adam K. Leroy, Laura A. Lopez, Hsi-An Pan, Patricia Sanchez-Blazquez, Francesco Santoro, Eva Schinnerer, David A. Thilker, Bradley C. Whitmore, Elizabeth J. Watkins, Thomas G. Williams
Summary: Connecting the gas in H II regions to the underlying ionizing radiation source helps us understand stellar feedback and the evolution of H II regions. Using PHANGS-MUSE, we detect and measure physical properties of nearly 24,000 H II regions across 19 galaxies. By analyzing associations with ionizing sources, we find correlations between association ages and various properties, suggesting an evolutionary sequence. We also observe correlations with local metallicity variations, indicating preferential star formation in metal-rich areas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Dominik R. G. Schleicher, Bastian Reinoso, Ralf S. Klessen
Summary: Numerical simulations have shown the occurrence of 'supercompetitive accretion', which refers to a situation where only the central few objects grow supermassive while a larger number of stars compete for the reservoir, with significant accretion flows. This study explores this phenomenon using analytical estimates for growth via collisions and accretion, considering both self-gravity and Bondi-Hoyle accretion. The results are validated through comparison with numerical simulations, confirming that supercompetitive accretion is a valid mechanism for the formation of very massive objects in the early Universe.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Filippo Santoliquido, Michela Mapelli, Giuliano Iorio, Guglielmo Costa, Simon C. O. Glover, Tilman Hartwig, Ralf S. Klessen, Lorenzo Merli
Summary: Population III (Pop. III) binary stars are likely responsible for the first stellar-born binary black hole (BBH) mergers in the Universe. We examine the uncertainties in the merger rate density evolution and mass spectrum of Pop. III BBHs by considering different formation histories and initial orbital properties. The primary sources of uncertainty are the orbital properties and star formation history, which significantly affect the BBH merger rate and its characteristics. Overall, the typical masses of Pop. III BBHs are larger than those of BBHs from metal-rich stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
E. Maconi, J. D. Soler, S. Reissl, P. Girichidis, R. S. Klessen, P. Hennebelle, S. Molinari, L. Testi, R. J. Smith, M. C. Sormani, J. W. Teh, A. Traficante
Summary: This study presents synthetic observations of polarized dust emission within a cavity in the interstellar medium, emphasizing the importance of studying the Local Bubble in further detail. The results suggest that the cavity acts as a translucent polarization filter due to its local density enhancement and coherent magnetic field.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
R. Dominguez, Eric W. Pellegrini, Ralf S. Klessen, Daniel Rahner
Summary: In order to replicate the evolution of embedded star clusters in 30 Doradus, particularly the compact star cluster R136 and its surroundings, we utilized the NBODY6++GPU stellar dynamics code to calculate the dynamics of stars embedded in evolving molecular clouds. By exploring clouds with various initial masses and star formation efficiencies, we were able to find the best set of parameters that can reproduce the observations. Our findings indicate the presence of multiple generations of stars in 30 Doradus, supported by measurements of mass segregation and density profile in the central region of the cluster.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Stefan Reissl, Ralf S. S. Klessen, Eric W. W. Pellegrini, Daniel Rahner, Rudiger Pakmor, Robert Grand, Facundo Gomez, Federico Marinacci, Volker Springel
Summary: Magnetic fields play a critical role in the formation and evolution of the Milky Way, influencing the interstellar medium and star formation process. Observations of Faraday rotation measures across the Galaxy provide insights into the magnetic field's topology and strength. By combining cosmological magnetohydrodynamic simulations with a realistic model for the local interstellar medium, researchers accurately predict the observed Faraday sky, reproducing observations at both global and local scales. These findings contribute to a better understanding of the origin of magnetic fields in our Galaxy.