Article
Astronomy & Astrophysics
A. Audibert, F. Combes, S. Garcia-Burillo, L. Hunt, A. Eckart, S. Aalto, V Casasola, F. Boone, M. Krips, S. Viti, S. Muller, K. Dasyra, P. van der Werf, S. Martin
Summary: ALMA observations of NGC1808 reveal a nuclear spiral and a circumnuclear disk, with detections of dense gas line tracers like HCN, HCO+, and CS. Presence of an active galactic nucleus is indicated at the nucleus, with regular rotation observed within a radius of 400 pc, except for non-circular motions in the nuclear spiral arms. Potential weak outflow attributed to AGN feedback is observed along with a molecular outflow likely due to supernovae feedback at >= 250 pc in the NE direction, connected to a kpc-scale superwind.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Jeremy Karam, Alison Sills
Summary: Research shows that in the formation of star clusters in giant molecular clouds, collisions at speeds above 10 km/s do not result in an immediate formation of a single cluster, while collisions at lower speeds eventually merge, but over a longer time period. The structure of the resulting cluster does not fit any standard density distribution, and the clusters continue to expand and are not in equilibrium.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jeremy Karam, Alison Sills
Summary: The formation of star clusters involves the growth of smaller subclusters through the accretion of gas from the giant molecular cloud (GMC). The two main accretion mechanisms are from dense filaments and from the ambient background of the cloud. Simulations show that the accreting star cluster loses some mass while gaining mass from the background or filament, but the overall mass of the cluster continues to increase.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
L. M. Hogarth, A. Saintonge, L. Cortese, T. A. Davis, S. M. Croom, J. Bland-Hawthorn, S. Brough, J. J. Bryant, B. Catinella, T. J. Fletcher, B. Groves, J. S. Lawrence, A. R. Lopez-Sanchez, M. S. Owers, S. N. Richards, G. W. Roberts-Borsani, E. N. Taylor, J. van de Sande, N. Scott
Summary: The study found no significant difference in global gas fractions or star-formation efficiencies between galaxies powering outflows and a control sample. However, the molecular gas in outflow-type galaxies was found to be distributed more centrally than in control galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shameer Abdeen, Benjamin L. Davis, Rafael Eufrasio, Daniel Kennefick, Julia Kennefick, Ryan Miller, Deanna Shields, Erik B. Monson, Calla Bassett, Harry O'Mara
Summary: The study examines evidence for age gradients using star formation history (SFH) maps and spatially resolved stellar clusters, finding secondary peaks in cluster distributions indicate the presence of an age gradient. Analysing SFH maps of 12 galaxies reveals a tightening of spiral arms with increasing age, with a probability of 69% +/- 25% that pitch angle values decrease with age, supporting the previous studies on the tightening of spiral patterns in galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Adam B. Watts, Barbara Catinella, Luca Cortese, Chris Power, Sara L. Ellison
Summary: Observations of disturbances in the cold neutral atomic hydrogen (HI) in galaxies are common, but the reasons for these disturbances remain unclear. Studies using ALFALFA and xGASS surveys, as well as post-merger galaxies, show that the link between global HI asymmetry and the gas properties of galaxies is complex and needs further exploration.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Jorge Moreno, Paul Torrey, Sara L. Ellison, David R. Patton, Connor Bottrell, Asa F. L. Bluck, Maan H. Hani, Christopher C. Hayward, James S. Bullock, Philip F. Hopkins, Lars Hernquist
Summary: The study shows that close encounters in interacting galaxies significantly increase cool gas budgets, leading to enhanced star formation. Additionally, galaxies with high global star formation rates experience intense nuclear star formation enhancement in the central region, while those with low global SFR are suppressed in the central region.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Eric P. Andersson, Florent Renaud, Oscar Agertz
Summary: The study suggests that runaway stars might contribute to the phenomenon of star formation in the outskirts of spiral galaxies, enabling the appearance of star formation in regions with extremely low gas surface densities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
R. Darma, M. Arifyanto, M. B. N. Kouwenhoven
Summary: Recent observations and statistical identifications have shed light on the formation and evolution of star clusters, particularly binary star clusters. N-body simulations have shown that binary star clusters can form from diverse initial conditions, with a higher level of initial substructure leading to a greater fraction of binary star clusters. Over time, the number of binary star clusters decreases due to mergers or dissolution of the binary systems, with a higher survival rate in the LMC compared to the Milky Way. Multiple clusters are also rapidly formed, with the merging process leading to fast rotating star clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Catalina Casanueva, Claudia del P. Lagos, Nelson D. Padilla, Thomas A. Davison
Summary: This study investigates the origin of misalignments between the stellar and star-forming gas components in simulated galaxies. The research finds that internal galaxy properties play a crucial role in determining whether the gas aligns with the stellar component, and the environment is also important in setting the conditions for misalignments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Marcel Lotz, Klaus Dolag, Rhea-Silvia Remus, Andreas Burkert
Summary: Post-starburst (PSB) galaxies represent a transition population between star-forming and quiescent galaxies, evolving through mergers, black hole activity, and AGN feedback. Field PSBs are primarily quenched by AGN feedback, while cluster PSBs are mostly shut down by environmental mechanisms such as ram-pressure stripping.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
C. Murugeshan, V. A. Kilborn, B-Q For, O. Wong, J. Wang, T. Westmeier, A. R. H. Stevens, K. Spekkens, P. Kamphuis, L. Staveley-Smith, K. Lee-Waddell, D. Kleiner, B. S. Koribalski, M. E. Cluver, S-H Oh, J. Rhee, B. Catinella, T. N. Reynolds, H. Denes, A. Elagali
Summary: Using high-resolution ASKAP observations of galaxies in the Eridanus supergroup, we studied their HI, angular momentum, and star formation properties, finding consistency with previous works. Environmental processes, such as tidal interactions, were found to significantly impact the relationship between atomic gas fraction and integrated atomic disc stability parameter in Eridanus galaxies. The majority of Eridanus galaxies were also found to be HI deficient compared to normal star-forming galaxies in the field, with indications of suppression in star formation due to their environment.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Daniel Maschmann, Anne-Laure Melchior, Francoise Combes, Barbara Mazzilli Ciraulo, Jonathan Freundlich, Anaelle Halle, Alexander Drabent
Summary: This study focuses on the mass assembly process and the evolution of molecular gas and star-formation activity in galaxies. By observing the molecular-gas content of double-peak emission-line galaxies, the study reveals a central star-formation enhancement, indicating a possible link to galaxy interactions or mergers. The findings also suggest that these galaxies have a larger amount of molecular gas and a lower star-formation efficiency compared to expected values.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Jennifer R. Cooper, Gregory H. Rudnick, Gabriel G. Brammer, Tyler Desjardins, Justin L. Mann, Benjamin J. Weiner, Alfonso Aragon-Salamanca, Gabriella De Lucia, Vandana Desai, Rose A. Finn, Pascale Jablonka, Yara L. Jaffe, John Moustakas, Damien Sperone-Longin, Harry I. Teplitz, Benedetta Vulcani, Dennis Zaritsky
Summary: This study investigates the role of environment on star formation rates (SFRs) of galaxies at different cosmic densities. By observing 163 galaxies in four EDisCS clusters, it is found that the distribution of main sequence galaxies is similar in different environments, with little dependence on SFRs. Additionally, it is observed that 21 galaxies with significant Hα emissions are classified as UVJ-quiescent, possibly indicating a quenching of star formation process.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Juan M. Espejo Salcedo, Karl Glazebrook, Deanne B. Fisher, Sarah M. Sweet, Danail Obreschkow, A. M. Swinbank, Steven Gillman, Alfred L. Tiley
Summary: Detailed measurements of stellar specific angular momentum of 10 star-forming galaxies at redshifts around 1.5-2 were conducted using high and low spatial resolution integral field spectroscopic data. The study showed that higher resolution kinematics are required for identifying discs in these galaxies. Systematic errors in measuring j(*) between different analyses were found to be primarily due to the choice of surface mass density model and the measurement of effective radius from photometry.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Eduardo Vitral, Gary A. Mamon
Summary: Analyzing the motions and density profiles of the nearby globular cluster NGC 6397, it was found that there is strong evidence suggesting the presence of a central dark component rather than an intermediate-mass black hole. This dark component may be composed of unresolved objects, indicating a high concentration of compact stars due to dynamical friction. The results also suggest that stellar-mass black holes could dominate this dark component, potentially playing a role in the gravitational wave events detected by LIGO.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
J. Read, G. A. Mamon, E. Vasiliev, L. L. Watkins, M. G. Walker, J. Penarrubia, M. Wilkinson, W. Dehnen, P. Das
Summary: In this study, four different mass modelling methods were applied to mock data for spherical stellar systems, showing good recovery of density and velocity anisotropy for isotropic and tangentially anisotropic data, but facing challenges with radially anisotropic data. Only methods incorporating shape information of the velocity distribution function were able to break the degeneracy between the density profile and the velocity anisotropy for line-of-sight data, while including proper motion data led to further improvements in recovering both radial density and velocity anisotropy profiles.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. Trevisan, G. A. Mamon, T. X. Thuan, F. Ferrari, L. S. Pilyugin, A. Ranjan
Summary: Based on the analysis of over 400,000 Sloan Digital Sky Survey spectra, a large sample of more massive very young galaxies (VYGs) has been identified. These VYGs tend to be more compact, dusty, asymmetric, and clumpy compared to control sample galaxies (CSGs). Additionally, VYGs are found to be more gas rich and are more likely to reside in the inner parts of low-mass groups and interact with neighbor galaxies. Gas-rich interactions and mergers are suggested as the main triggers of recent star formation in low-redshift VYGs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Surajit Paul, Prateek Gupta, Sameer Salunkhe, Shubham Bhagat, Satish Sonkamble, Manish Hiray, Pratik Dabhade, Somak Raychaudhury
Summary: The upgraded Giant Metrewave Radio Telescope (uGMRT) and the Low Frequency Array (LoFAR) have enabled the exploration of low-mass galaxy clusters in radio observations. Diffuse radio emission has been detected from four out of the 12 low-mass galaxy clusters studied, including relic-like emission and halo-relic systems. These findings suggest a high detection rate and powerful radio emission in these objects, expanding the prospects of studying radio emission in galaxy clusters across a wider mass range.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Mousumi Mahato, Pratik Dabhade, D. J. Saikia, Francoise Combes, Joydeep Bagchi, L. C. Ho, Somak Raychaudhury
Summary: Giant radio quasars (GRQs) and small radio quasars (SRQs) have similar spectral index and black hole mass distributions, but SRQs have higher radio core power and core dominance factor compared to GRQs. On the other hand, GRQs have higher black hole mass and Eddington ratio compared to giant radio galaxies (GRGs). The accretion disc luminosity of GRQs is correlated with the radio core and jet power, indicating disc-jet coupling. The distributions of Eddington ratios of GRGs and GRQs are bimodal, similar to those of small radio galaxies (SRGs) and SRQs, suggesting independence of size on the accretion state.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Gerrit Schellenberger, Simona Giacintucci, Lorenzo Lovisari, Ewan O'Sullivan, Jan Vrtilek, Laurence P. David, Jean-Baptiste Melin, Dharam Vir Lal, Stefano Ettori, Konstantinos Kolokythas, Mauro Sereno, Somak Raychaudhury
Summary: Mergers between galaxy clusters can lead to shocks and radio relics in the intracluster medium. A2108, identified as a likely merger system, exhibits X-ray underluminosity and a disturbed X-ray morphology. Radio observations confirm the presence of a radio relic, and its spectral properties suggest a shock-reacceleration scenario. The study highlights the importance of studying low-mass mergers and the use of different observational techniques to understand the phenomenon.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
M. B. Pandge, Ruta Kale, Pratik Dabhade, Mousumi Mahato, Somak Raychaudhury
Summary: In this study, original GMRT radio observations of the galaxy cluster Abell 725 at a redshift of 0.09 revealed steep-spectrum diffuse structures and a wide-angle-tail (WAT) radio source associated with the brightest cluster galaxy. The morphology of the WAT suggests interaction with the intracluster medium, indicating an early stage of evolution for the cluster. The system is proposed to be a radio galaxy with trailing antique filaments based on component morphology and spectral indices.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. Taverna, E. Diaz-Gimenez, A. Zandivarez, G. A. Mamon
Summary: This study used five different semi-analytical models of galaxy formation to identify isolated dense groups in 3D real space, containing at least three galaxies. It found that the Hickson-like algorithm in redshift space is poor at recovering 3D compact groups (CGs), with a high percentage of spurious systems and low completeness. The low completeness of the extracted CG sample is mainly due to the flux limits of the selection criteria.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Konstantinos Kolokythas, Sravani Vaddi, Ewan O'Sullivan, Ilani Loubser, Arif Babul, Somak Raychaudhury, Patricio Lagos, Thomas H. Jarrett
Summary: Using multiband data, this study examines the star formation activity of nearby group-dominant early-type galaxies and explores the relation between star formation, gas content, and the local environment. The findings suggest that only a small fraction of the galaxies exhibit recent active star formation, while the majority show no significant star formation. The study also highlights the association between central group galaxy evolution and gas mass availability.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ruchika Seth, Ewan O'Sullivan, Biny Sebastian, Somak Raychaudhury, Gerrit Schellenberger, Christopher P. Haines
Summary: This study presents a combined radio/X-ray study of six massive galaxy clusters, aiming to determine the potential for heating of the intra-cluster medium by non-central radio galaxies. The study finds that the radio luminosity of radio galaxies is influenced by the star formation in the galaxy and estimates the range of jet powers. The results suggest that non-central sources have a significant impact on the heating of the intra-cluster medium.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Eduardo Vitral, Kyle Kremer, Mattia Libralato, Gary A. Mamon, Andrea Bellini
Summary: By analysing data from Gaia EDR3 and re-calibrated HST proper motion, we detected a dark central mass (DCM) in the globular clusters NGC 6397 and NGC 3201. The use of Bayesian mass-orbit modelling code MAMPOSSt-PM and Monte Carlo N-body code CMC provided consistent results and confirmed the accuracy of these techniques. These findings have implications for understanding various astrophysical phenomena in clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Francois Hammer, Hefan Li, Gary A. Mamon, Marcel S. Pawlowski, Piercarlo Bonifacio, Yongjun Jiao, Haifeng Wang, Jianling Wang, Yanbin Yang
Summary: Halo inhabitants in the Milky Way include individual stars, stellar streams, star, and globular clusters, and dwarf galaxies. The study compares globular clusters and dwarf galaxies, finding that their half-light radius is related to their orbital pericentre and total energy. The study also suggests that the accretion epoch of stellar systems in the Milky Way halo can be calibrated by the total orbital energy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Eduardo Vitral, Mattia Libralato, Kyle Kremer, Gary A. Mamon, Andrea Bellini, Luigi R. Bedin, Jay Anderson
Summary: Recent studies of nearby globular clusters have found excess dark mass in their extended cores, likely composed of white dwarfs or stellar-mass black holes. By analyzing the closest globular cluster M4, we determine isotropic motions in the cluster core and tangential motions in the outskirts. We measure a dark central mass and propose two scenarios - an intermediate-mass black hole or a population of stellar remnants - for further investigation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Zandivarez, E. Diaz-Gimenez, A. Taverna, G. A. Mamon
Summary: Using over 3000 compact groups (CGs) of galaxies extracted from mock catalogues built from semi-analytical models (SAMs) of galaxy formation, the study shows that the CG assembly channel affects the properties and evolution of galaxies. The characteristics of CG galaxies are related to their stellar masses, and the assembly history of CGs also has an impact on the evolution of galaxies. Classifying CGs according to their assembly channel can distinguish different paths by which galaxies transform their properties throughout their history.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Review
Physics, Applied
M. Bailes, B. K. Berger, P. R. Brady, M. Branchesi, K. Danzmann, M. Evans, K. Holley-Bockelmann, B. R. Iyer, T. Kajita, S. Katsanevas, M. Kramer, A. Lazzarini, L. Lehner, G. Losurdo, H. Luck, D. E. McClelland, M. A. McLaughlin, M. Punturo, S. Ransom, S. Raychaudhury, D. H. Reitze, F. Ricci, S. Rowan, Y. Saito, G. H. Sanders, B. S. Sathyaprakash, B. F. Schutz, A. Sesana, H. Shinkai, X. Siemens, D. H. Shoemaker, J. Thorpe, J. F. J. van den Brand, S. Vitale
Summary: Gravitational-wave observations have provided significant insights into cataclysmic events in the Universe in recent years, signaling a bright future for the field. The Roadmap for the next two decades outlines the potential growth in bandwidth and sensitivity of future detectors and the anticipated science results.
NATURE REVIEWS PHYSICS
(2021)