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
Patrick Hennebelle, Ugo Lebreuilly, Tine Colman, Davide Elia, Gary Fuller, Silvia Leurini, Thomas Nony, Eugenio Schisano, Juan D. Soler, Alessio Traficante, Ralf S. Klessen, Sergio Molinari, Leonardo Testi
Summary: The physical origin of the stellar initial mass function (IMF) remains a subject of debate despite decades of theoretical efforts. This study aimed to understand the influence of various physical processes on the IMF, including radiative stellar feedback, magnetic fields, and non-ideal magneto-hydrodynamics. Numerical simulations were conducted with different scenarios, and analytical models were compared with the results. The study found that the combination of magnetic field and radiative feedback significantly impacts the stellar mass spectrum, reducing fragmentation and leading to the formation of more massive stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Madeleine Stewart, Christoph Federrath
Summary: The structure and star formation activity of a molecular cloud are closely related to its internal turbulence. This study develops a new method to accurately measure the turbulent velocity dispersion of a molecular cloud, taking into account the gradient correction. The results show that with the suitable correction factor and appropriate filters, the 3D turbulent velocity dispersion can be recovered, which is crucial for understanding the dynamics of molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Henry B. Lane, Michael Y. Grudic, David Guszejnov, Stella S. R. Offner, Claude-Andre Faucher-Giguere, Anna L. Rosen
Summary: Simulating isolated giant molecular clouds is important for studying star formation dynamics, but the initial conditions of turbulence are uncertain. Researchers have developed a new simulation setup that combines advantages of previous methods and found that external driving can significantly suppress star formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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
T. Nony, J. -F. Robitaille, F. Motte, M. Gonzalez, I. Joncour, E. Moraux, A. Men'shchikov, P. Didelon, F. Louvet, A. S. M. Buckner, N. Schneider, S. L. Lumsden, S. Bontemps, Y. Pouteau, N. Cunningham, E. Fiorellino, R. Oudmaijer, P. Andre, B. Thomasson
Summary: The study characterizes the structure of the NGC 2264 molecular cloud and identifies a population of clumps with strong mass segregation, concentrated in the central subregion. The combined study of clump and young stellar object populations suggests a dynamical scenario of star formation, where global collapse drives clumps into centrally concentrated ridges and some massive YSOs remain clustered while others disperse. Mass segregation in star clusters may be inherited from clumps, originating from the mass assembly phase of molecular clouds.
ASTRONOMY & ASTROPHYSICS
(2021)
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
Lars Mattsson, Robert Hedvall
Summary: The dynamics of interstellar dust particles in forced compressible transonic turbulence simulations were investigated, showing that self-gravity can significantly accelerate large grains and increase clustering for intermediate-sized grains. This suggests that self-gravity effects can play a crucial role in dust aggregation/coagulation even in non-Jeans-unstable turbulent systems.
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
N. Schneider, V Ossenkopf-Okada, S. Clarke, R. S. Klessen, S. Kabanovic, T. Veltchev, S. Bontemps, S. Dib, T. Csengeri, C. Federrath, J. Di Francesco, F. Motte, Ph Andre, D. Arzoumanian, J. R. Beattie, L. Bonne, P. Didelon, D. Elia, V Konyves, A. Kritsuk, B. Ladjelate, Ph Myers, S. Pezzuto, J. F. Robitaille, A. Roy, D. Seifried, R. Simon, J. Soler, D. Ward-Thompson
Summary: The probability distribution functions of total hydrogen column density (N-PDFs) are useful for understanding the structure of the interstellar medium. The N-PDFs show different characteristics at low and high column densities, with a transition from a double-log-normal distribution to one or two power law tails. The different cloud types exhibit distinct features, possibly related to turbulence, gravity, radiative feedback, and magnetic fields.
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
V Pelgrims, E. Ntormousi, K. Tassis
Summary: In this study, synthesized dust polarization maps were generated from global magneto-hydrodynamic simulations of Milky-Way-sized galaxies, and their power spectra were analyzed. The research found that the observer's location significantly affects the polarization power spectra, and there are statistical differences between measurements from within the spiral arms and the inter-arm regions. The statistical properties of the polarization power spectra were not found to be directly correlated with local physical quantities, but there were indications that the global strength of the magnetic field may play a role in shaping the power spectrum characteristics.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Tritsis, C. Federrath, K. Willacy, K. Tassis
Summary: Non-ideal magnetohydrodynamic effects are crucial in understanding the formation of stars. In this study, we modify the FLASH code to include a detailed treatment of non-ideal MHD and investigate its role in collapsing pre-stellar cores. Our simulations show that the ion responsible for most of the conductivities is D-3(+), rather than H-3(+) as previously thought.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Konstantinos Tassis, Vasiliki Pavlidou
Summary: Molecular clouds in the central molecular zone show extraordinary turbulences, and the interactions between clouds and crossing stars may account for this phenomenon. Energy deposition by stellar winds of crossing massive stars can explain the turbulence features, while dynamical friction by crossing stars is not a significant driver.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Konstantinou, V Pelgrims, F. Fuchs, K. Tassis
Summary: This study aims to investigate the influence of cloud shape and viewing angle on the angular power spectra measured on thermal dust polarization maps. By simulating and calculating the polarization power spectra, the researchers found that both filament-like and sheet-like structures can lead to similar E/B power asymmetry and TE correlation. The results suggest that interpreting these observations based solely on filament characteristics is risky and the connection to the magnetic field geometry should also be considered.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
R. Skalidis, K. Tassis, G. Panopoulou, J. L. Pineda, Y. Gong, N. Mandarakas, D. Blinov, S. Kiehlmann, J. A. Kypriotakis
Summary: This study investigates the role of magnetic fields in the transition from atomic to molecular gas in the interstellar medium. Through observations and analysis of a cloud, the researchers find that magnetic fields play a significant role in the dynamics of the cloud, with atomic gas preferentially accumulating along the field lines to form molecular gas. The morphology of the magnetic field is better probed by the total column density shape of the cloud rather than its atomic column density shape.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Tritsis, F. Bouzelou, R. Skalidis, K. Tassis, T. Ensslin, G. Edenhofer
Summary: Recent research has found that the Musca molecular cloud has a sheet-like geometry that extends along the line-of-sight dimension. This discovery is crucial for understanding the physics behind the formation of the first generation of stars within molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Enrique Lopez-Rodriguez, Sui Ann Mao, Rainer Beck, Alejandro S. Borlaff, Evangelia Ntormousi, Konstantinos Tassis, Daniel A. Dale, Julia Roman-Duval, Kandaswamy Subramanian, Sergio Martin-Alvarez, Pamela M. Marcum, Susan E. Clark, William T. Reach, Doyal A. Harper, Ellen G. Zweibel
Summary: This article presents the first data release of the Survey on extragalactic magnetism with SOFIA (SALSA Legacy Program), which includes high-angular resolution polarimetric imaging observations of 14 nearby galaxies using HAWC+ instrument. Far-infrared polarimetric observations effectively trace the thermal polarized emission of magnetically aligned dust grains across the galaxy disks and reveal general trends in the emissive polarization fraction.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
V. Pelgrims, G. V. Panopoulou, K. Tassis, V. Pavlidou, A. Basyrov, D. Blinov, E. Gjerlow, S. Kiehlmann, N. Mandarakas, A. Papadaki, R. Skalidis, A. Tsouros, R. M. Anche, H. K. Eriksen, T. Ghosh, J. A. Kypriotakis, S. Maharana, E. Ntormousi, T. J. Pearson, S. B. Potter, A. N. Ramaprakash, A. C. S. Readhead, I. K. Wehus
Summary: We propose a Bayesian method for tomographic decomposition of the plane-of-sky orientation of the magnetic field using stellar polarimetry and distance information. This method allows for the reconstruction of the magnetized interstellar medium (ISM) in three dimensions within dusty regions. The method is effective at recovering cloud properties when the polarization induced by a cloud is higher than a certain threshold, and it also provides a way to characterize ISM turbulence and magnetic field strength.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
N. Mandarakas, D. Blinov, D. R. Aguilera-Dena, S. Romanopoulos, V. Pavlidou, K. Tassis, J. Antoniadis, S. Kiehlmann, A. Lychoudis, L. F. Tsemperof Kataivatis
Summary: We report on the follow-up observation of the optical polarimetry for the extremely bright long gamma-ray burst GRB 210619B. The observation results show a 5 sigma detection of polarization with a value of P=1.5 +/- 0.3 and polarization angle EVPA=8 +/- 6 degrees. The polarization is likely constant during our observation period and is intrinsic to the GRB afterglow, corrected for interstellar medium-induced polarization.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Enrique Lopez-Rodriguez, Alejandro S. Borlaff, Rainer Beck, William T. Reach, Sui Ann Mao, Evangelia Ntormousi, Konstantinos Tassis, Sergio Martin-Alvarez, Susan E. Clark, Daniel A. Dale, Ignacio del Moral-Castro
Summary: This study characterizes the morphology of the ordered magnetic fields in the interstellar medium (ISM) of the closest merging spiral galaxies, the Antennae galaxies. It reveals that the 154 μm magnetic fields are more ordered than the 11 cm magnetic fields. The turbulent-to-ordered 154 μm magnetic field increases at the galaxy cores and star-forming regions. It suggests that the amplified magnetic fields may support the gas flow between the galaxies and the tidal tail.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
R. Skalidis, K. Gkimisi, K. Tassis, G. V. Panopoulou, V. Pelgrims, A. Tritsis, P. F. Goldsmith
Summary: This study investigates the role of magnetohydrodynamic (MHD) waves in the CO chemistry in molecular clouds. The results suggest that MHD waves can enhance the formation of CO and create the observed periodic structures. Additionally, the study finds a correlation between the strength and orientation of the magnetic field and the distribution of CO intensity.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Giorgos Korkidis, Vasiliki Pavlidou, Konstantinos Tassis
Summary: By simulating the evolution of the universe, an offset was found between the predicted and measured turnaround density, which slightly evolves with redshift and correlates with the deviation from spherical symmetry of dark matter halos. A sphericity-selected halo sample was used to recover the simulated cosmology and confirmed that the evolution of the turnaround density encodes the cosmology in N-body simulations.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
R. Skalidis, K. Tassis, V. Pavlidou
Summary: Understanding the energy exchange between kinetic and magnetic forms in MHD turbulence is crucial for studying various systems. By analyzing the energetics of compressible and sub-Alfvenic turbulence, researchers have found that the coupling between ordered and fluctuating magnetic fields is the main source of energy transfer from magnetic to kinetic. This finding is supported by numerical simulations.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Alejandro S. S. Borlaff, Enrique Lopez-Rodriguez, Rainer Beck, Susan E. E. Clark, Evangelia Ntormousi, Konstantinos Tassis, Sergio Martin-Alvarez, Mehrnoosh Tahani, Daniel A. A. Dale, Ignacio del Moral-Castro, Julia Roman-Duval, Pamela M. M. Marcum, John E. E. Beckman, Kandaswamy Subramanian, Sarah Eftekharzadeh, Leslie Proudfit
Summary: We analyzed the magnetic field structure of galaxies using far-infrared and radio polarimetric observations and found that the morphology of the magnetic field differs at different wavelengths. The magnetic field in the far-infrared wavelengths is more disordered, especially in spiral galaxies. This suggests that the far-infrared wavelengths are more sensitive to the activity of star-forming regions and molecular clouds.
ASTROPHYSICAL JOURNAL
(2023)
Proceedings Paper
Engineering, Mechanical
Ramya M. Anche, Siddharth Maharana, A. N. Ramaprakash, Pravin Khodade, Deepa Modi, Chaitanya Rajarshi, John A. Kypriotakis, Dmitry Blinov, Hans Kristian Eriksen, Tuhin Ghosh, Georgia Panopoulou, Vincent Pelgrims, Raphael Skalidis, Timothy J. Pearson, Eirik Gjerlow, Nikolaos Mandarakas, Vasiliki Pavlidou, Stephen B. Potter, Anthony C. S. Readhead, Konstantinos Tassis, Artem Basyrov, Katerina Papadaki, Trygve Leithe Svalheim, Ingunn K. Wehus
Summary: Two unique wide-field and high-accuracy polarimeters named WALOP-North and WALOP-South are being developed at IUCAA, India, to create a large area optical polarization map of the sky. These instruments are designed to achieve a linear polarimetric measurement accuracy of 0.1% across a field of view of 30x30 arcminutes.
ADVANCES IN OPTICAL AND MECHANICAL TECHNOLOGIES FOR TELESCOPES AND INSTRUMENTATION V
(2022)