Publications (78)
The post-gas expulsion coalescence of embedded clusters as an origin of open clusters
J. W. Zhou, Sami Dib, Pavel Kroupa
The mismatch between the mass function of the Milky Way's embedded clusters (ECs) and that of open clusters (OCs) raises the question of whether each OC originates from a single EC…
The evolution of the core mass function by gas accretion
Sami Dib
We show how the mass function of dense cores (CMF) which results from the gravoturbulent fragmentation of a molecular cloud evolves in time under the effect of gas accretion. Accre…
Variation of the high-mass slope of the stellar initial mass function: Theory meets observations
Sami Dib
We present observational evidence of the correlation between the high-mass slope of the stellar initial mass function (IMF) in young star clusters and their stellar surface density…
Structure and mass segregation in Galactic stellar clusters
Sami Dib, Stefan Schmeja, Richard J. Parker
We quantify the structure of a very large number of Galactic open clusters and look for evidence of mass segregation for the most massive stars in the clusters. We characterise the…
Early Stages of Protostellar Disk Evolution: A Link to the Initial Cloud Core
Majd Noel, Rahul Khanna, Shahram Abbassi +2
We study the structure and evolution of the very early protostellar disk (``protodisk'') just after protostar formation, where disk self-gravity dominates and the stellar contribut…
Inversely synthesizing the core mass function of high-mass star-forming regions from the canonical initial mass function
J. W. Zhou, Pavel Kroupa, Sami Dib
Many studies have revealed that the core mass function (CMF) in high-mass star-forming regions is top-heavy. In this work, we start from the canonical initial mass function (IMF) t…
Brane cosmology with variable tension
José Antonio Belinchón, Sami Dib
We study brane-world models and demonstrate that such models do not admit self-similar solutions through the matter collineation approach. By introducing the hypothesis of variable…
Properties of an accretion disc with a power-law stress-pressure relationship
Mohsen Shadmehri, Fazeleh Khajenabi, Sami Dib +1
Recent numerical simulations of magnetized accretion discs show that the radial-azimuthal component of the stress tensor due to the magnetorotational instability (MRI) is well repr…
The merger of hard binaries in globular clusters as the primary channel for the formation of second generation stars
Valery Kravtsov, Sami Dib, Francisco A. Calderon
We have recently presented observational evidence which suggests that the origin of the second generation (G2) stars in globular clusters (GCs) is due to the binary-mediated collis…
Star formation efficiency and scaling relations in parsec-scale cluster-forming clumps
V. Rawat, M. R. Samal, A. Zavagno +5
Numerical simulations predict that clumps (1 pc) should form stars at high efficiency to produce bound star clusters. We conducted a statistical study of 17 nearby cluster-fo…
ALMA-QUARKS view of W49N: Multipolar episodic outflow associated with the most energetic Galactic water maser
Yunfan Jiao, Tie Liu, Wenyu Jiao +28
We present a detailed investigation of a multipolar episodic molecular outflow in the mini-starburst region W49N, which hosts the most luminous water maser in the Galaxy. Using hig…
The structure and characteristic scales of the HI gas in galactic disks
Sami Dib, Jonathan Braine, Maheswar Gopinathan +9
The spatial distribution of the HI gas in galaxies holds important clues on the physical processes that shape the structure and dynamics of the interstellar medium (ISM). In this w…
The currently observed clumps cannot be the "direct" precursors of the currently observed open clusters
J. W. Zhou, Sami Dib, Pavel Kroupa
We categorized clumps, embedded clusters, and open clusters and conducted a comparative analysis of their physical properties. Overall, the radii of open clusters are significantly…
Feedback Regulated Star Formation: From Star Clusters to Galaxies
Sami Dib
This paper summarises results from semi-analytical modelling of star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form un…
The ALMA-QUARKS Survey: III. Clump-to-core fragmentation and search for high-mass starless cores
Dongting Yang, Hong-Li Liu, Tie Liu +43
The Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures (QUARKS) survey observed 139 infrared-bright (IR-bright) massive proto…
Thin accretion disc with a corona in a central magnetic field
Fazeleh Khajenabi, Mohsen Shadmehri, Sami Dib
We study the steady-state structure of an accretion disc with a corona surrounding a central, rotating, magnetized star. We assume that the magneto-rotational instability is the do…
Evolution of starless cores in massive clumps seen by the ALMA ASHES and QUARKS surveys
Dongting Yang, Hong-li Liu, Sheng-li Qin +28
We present a systematic comparative analysis of 324 starless cores in early-phase infrared-dark clouds (IRDCs; ASHES survey) and evolved-phase infrared-bright clouds (IRBCs; QUARKS…
Primordial Mass Segregation in Starburst Stellar Clusters
Sami Dib, Mohsen Shadmehri, Maheswar Gopinathan +2
We present a model to explain the mass segregation and shallow mass functions observed in the central parts of dense and young starburst stellar clusters. The model assumes that th…
The star formation histories, star formation efficiencies and ionizing sources of ATLASGAL clumps with HII regions
J. W. Zhou, Sami Dib, Pavel Kroupa
1226 ATLASGAL clumps with HII regions were matched with radio sources in the CORNISH-North/South surveys, and 392 of them have corresponding radio sources. We determined the stella…
Structure of radiation dominated gravitoturbulent quasar discs
Mohsen Shadmehri, Fazeleh Khajenabi, Sami Dib
Self-gravitating accretion discs in a gravitoturbulent state, including radiation and gas pressures, are studied using a set of new analytical solutions. While the Toomre parameter…
Dynamical friction in an isentropic gas
Fazeleh Khajenabi, Sami Dib
When a gravitating object moves across a given mass distribution, it creates an overdense wake behind it. Here, we performed an analytical study of the structure of the flow far fr…
Surface convection: from the Sun to red giant stars
Laurent Piau, Pierre Kervella, Sami Dib +1
We check how the change in surface conditions between the Sun and red giant branch stars changes the characteristic surface convection length scale to be used in models. We investi…
Formation and Properties of Molecular Cloud Cores
Sami Dib, Roberto Galvan-Madrid, Jongsoo Kim +1
In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized…
Distances to dense cores that contain Very Low Luminosity Objects
G. Maheswar, Chang Won Lee, Sami Dib
The aim of the paper is to estimate distances to dense molecular cores that harbour Very Low Luminosity Objects (VeLLO) detected by Spitzer Space Telescope and to confirm their VeL…
The evolution of the internal structure of massive star forming regions in the Milky Way as revealed by ALMA
Sami Dib
We analyze the structure of 15 protocluster forming regions in the Milky Way using their mm continuum emission maps from the ALMA-IMF large program. The analysis of the cloud…
Molecular clouds as hubs in spiral galaxies : gas inflow and evolutionary sequence
J. W. Zhou, Sami Dib, Timothy A. Davis
We decomposed the molecular gas in the spiral galaxy NGC 628 (M74) into multi-scale hub-filament structures using the CO (2-1) line by the dendrogram algorithm. All leaf structures…
Core Mass Function: The Role of Gravity
Sami Dib, Axel Brandenburg, Jongsoo Kim +2
We analyze the mass distribution of cores formed in an isothermal, magnetized, turbulent, and self-gravitating nearly critical molecular cloud model. Cores are identified at two de…
Physical properties of embedded clusters in ATLASGAL clumps with HII regions
J. W. Zhou, Pavel Kroupa, Sami Dib
Using the optimal sampling model, we synthesized the embedded clusters of ATLASGAL clumps with HII regions (HII-clumps). The 0.1 Myr isochrone was used to estimate the bolometric l…
Stellar collisions in globular clusters: the origin of multiple stellar populations
Valery Kravtsov, Sami Dib, Francisco A. Calderon +1
Two generations of stars, G1 and G2, typically populate Galactic globular clusters (GCs). The origin of G2 stars is unclear. We uncover two empirical dependencies between GC charac…
The ALMA-ATOMS survey: Methanol emission in a large sample of hot molecular cores
Jiahang Zou, Tie Liu, Sheng-Li Qin +26
Methanol (CHOH) is a key complex organic molecule (COM) in the interstellar medium, widely used as a tracer of dense gas and hot molecular cores (HMCs). Using high-resolution…
The ALMA-QUARKS survey: Investigating Thermal Feedback of Massive Protostars in Hot Molecular Cores
Dezhao Meng, Tie Liu, Jarken Esimbek +33
We identify a sample of 83 spatially resolved hot molecular cores (HMCs) in the QUARKS survey, aiming at investigating thermal feedback from massive stars. Using CHCN\,(12--11)…
The Angular Momentum of Magnetized Molecular Cloud Cores: A 2D-3D Comparison
Sami Dib, Patrick Hennebelle, Jaime E. Pineda +4
We study the rotational properties of magnetized and self-gravitating molecular cloud cores formed in 2 very high resolution 3D molecular cloud simulations.The simulations have bee…
On the Gravitational Boundedness of Small Scale Structures in Molecular Clouds
Sami Dib, Jongsoo Kim
We investigate, in a set of 3D numerical simulations of driven, magnetized, isothermal, and self-gravitating molecular clouds (MCs), the statistical correlations between the energy…
The most massive star clusters in molecular clouds: Insights from the integrated cloud-wide initial mass function (ICIMF) theory
J. W. Zhou, Pavel Kroupa, Sami Dib
The combination of the high-resolution ALMA, JWST and HST observations provides unprecedented insights into the connection between individual molecular clouds and their internal st…
The extended law of star formation: the combined role of gas and stars
Sami Dib, Sacha Hony, Guillermo Blanc
We present a model for the origin of the extended law of star formation in which the surface density of star formation () depends not only on the local surface densit…
The orientations of molecular clouds in the outer Galaxy: Evidence for the scale of the turbulence driver ?
Sami Dib, C. Jakob Walcher, Mark Heyer +2
Supernova explosions inject a considerable amount of energy into the interstellar medium (ISM) in regions with high to moderate star formation rates. In order to assess whether the…
The Dependence of the Galactic Star Formation Laws on Metallicity
Sami Dib, Laurent Piau, Subhanjoy Mohanty +1
We describe results from semi-analytical modelling of star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form uniformly in…
Metal-THINGS: On the metallicity and ionization of ULX sources in NGC 925
Maritza A. Lara-López, Igor A. Zinchenko, Leonid S. Pilyugin +13
We present an analysis of the optical properties of three Ultra Luminous X-ray (ULX) sources identified in NGC 925. We use Integral field unit data from the George Mitchel spectrog…
Properties of the cores and filaments in the Ophiuchus molecular cloud and its L1688 hub-filament system
Bo-Sheng Jia, Guo-Yin Zhang, Alexander Menshchikov +9
Analyzing filaments and cores in molecular clouds is key to understanding galactic star formation and its environmental dependence. This paper studies the properties and distributi…
Self-similar cosmological solutions in f(R,T) gravity theory
José Antonio Belinchón, Carlos González, Sami Dib
We study the cosmological models under the self-similarity hypothesis. We determine the exact form that each physical and geometrical quantity may take in order that the F…
The galaxy-wide stellar initial mass function in the presence of cluster-to-cluster IMF variations
Sami Dib
We calculate the integrated galactic initial stellar mass function (IGIMF) in the presence of IMF variations in clusters. IMF Variations for a population of clusters are taken into…
Connecting Star Formation in the Milky Way and Nearby Galaxies -II. An Observationally Driven Analytical Model for Predicting Cloud-Scale Star Formation Rates
J. W. Zhou, Amelie Saintonge, Sami Dib +1
We construct a model by integrating observational constraints from the Milky Way and nearby galaxies to predict cloud-scale star formation rates (SFRs). In the model, we first esti…
Origin of open clusters revealed by the evolution of the m_maxM_ecl relation
J. W. Zhou, Sami Dib, Pavel Kroupa
Using the Gaia DR3 open cluster catalog, we identified the most massive star in each observed cluster. Examining the m_maxM_cluster relations across different age ranges, we fin…
The structure and characteristic scales of molecular clouds
Sami Dib, Sylvain Bontemps, Nicola Schneider +8
The structure of molecular clouds (MCs) holds important clues on the physical processes that lead to their formation and subsequent evolution. While it is well established that tur…
On the origin of the HI holes in the interstellar medium of dwarf irregular galaxies
Sami Dib, Andreas Burkert
We suggest that large HI holes observed in the interstellar medium (ISM) of galaxies such as the Large Magellanic Cloud (LMC) and Holmberg II (Ho II, DDO 50, UGC 4305) can form as…
The ALMA-QUARKS Survey: Properties of Hot Molecular Fragments in the Massive Protocluster IRAS 17233-3606
Li Chen, Sheng-Li Qin, Dongting Yang +29
To investigate the physical mechanisms of fragmentation within the hot molecular core of the massive protocluster IRAS 17233-3606 (G351.78-0.54), we carried out a detailed analysis…
The ALMA-QUARKS Survey: Discovery of Dusty Fibrils inside Massive Star-forming Clumps
Yan-Kun Zhang, Tie Liu, Wenyu Jiao +35
We report the discovery of more than 323 superfine dusty filamentary structures (fibrils) inside 121 massive star forming clumps that are located in widely different Galactic envir…
The ALMA-QUARKS survey: Evidence of a candidate high-mass prestellar core aside a bright-rimmed cloud IRAS 18290-0924
Dongting Yang, Hong-Li Liu, Shengli Qin +32
Although frequently reported in observations, the definitive confirmation of high-mass prestellar cores has remained elusive, presenting a persistent challenge in star formation st…
A misaligned protostellar disk fed by gas streamers in a barred spiral-like massive dense core
Xiaofeng Mai, Tie Liu, Xunchuan Liu +42
High-mass stars, born in massive dense cores (MDCs), profoundly impact the cosmic ecosystem through feedback processes and metal enrichment, yet little is known about how MDCs asse…
The Origin of the Arches Stellar Cluster Mass Function
Sami Dib, Jongsoo Kim, Mohsen Shadmehri
We investigate the time evolution of the mass distribution of pre-stellar cores (PSCs) and their transition to the initial stellar mass function (IMF) in the central parts of a mol…
A method to determine distances to molecular clouds using near-IR photometry
G. Maheswar, C. -W. Lee, H. C. Bhatt +2
Aims: We aim to develop a method to determine distances to molecular clouds using JHK near-infrared photometry. Methods: The method is based on a technique that aids spectral class…
The IMF of stellar clusters: effects of accretion and feedback
Sami Dib, Mohsen Shadmehri, Paolo Padoan +3
(abridged) We develop a model which describes the coevolution of the mass function of dense cores and of the IMF in a protocluster clump. In the model, cores injected in the clump…
The Lesser Role of Shear in Star Formation: Insight from the Galactic Ring Survey
Sami Dib, George Helou, Toby Moore +2
We analyse the role played by shear in regulating star formation in the Galaxy on the scale of individual molecular clouds. The clouds are selected from the 13^CO J=1-0 line of the…
The supernova rate-velocity dispersion relation in the interstellar medium
Sami Dib, Eric Bell, Andreas Burkert
We investigate the relationship between the velocity dispersion of the gas and the SN rate and feedback efficiency in the ISM. We explore the constancy of the velocity dispersion p…
Stellar collisions in globular clusters: Constraints on the initial mass function of the first generation of stars
Sami Dib, Valery V. Kravtsov, Hosein Haghi +2
Globular clusters display an anticorrelation between the fraction of the first generation of stars () and the slope of the present-day mass function of th…
Massive stars reveal variations of the stellar initial mass function in the Milky Way stellar clusters
Sami Dib, Stefan Schmeja, Sacha Hony
We investigate whether the stellar initial mass function (IMF) is universal, or whether it varies significantly among young stellar clusters in the Milky Way. We propose a method t…
The ALMA-QUARKS Survey: Evidence of an Explosive Molecular Outflow in IRAS 15520--5234
Ariful Hoque, Tapas Baug, Estrella Guzman +25
We present a study of the massive protocluster IRAS 155205234, which displays evidence of an explosive molecular outflow that unleashed a kinetic energy of at least 10 er…
The Virial Balance of Clumps and Cores in Molecular Clouds
Sami Dib, Jongsoo Kim, Enrique Vazquez-Semadeni +2
We study the instantaneous virial balance of clumps and cores (CCs) in 3D simulations of driven, MHD, isothermal molecular clouds (MCs). The models represent a range of magnetic fi…
Connecting Star Formation in the Milky Way and Nearby Galaxies. I. Comparability of Molecular Cloud Physical Properties
J. W. Zhou, Sami Dib
We used CO (2-1) and CO (1-0) data cubes to identify molecular clouds and study their kinematics and dynamics in three nearby galaxies and the inner Milky Way. When observed at sim…
Cloud Motion and magnetic fields: Four clouds in the Cepheus Flare region
Ekta Sharma, Maheswar G., Sami Dib
The Cepheus Flare region consists of a group of dark cloud complexes that are currently active in star formation. The aim of this work is to estimate the motion of four clouds, L11…
The ALMA-ATOMS survey: A sample of weak hot core candidates identified through line stacking
Zi-Yang Li, Xunchuan Liu, Tie Liu +33
Hot cores represent critical astrophysical environments for high-mass star formation, distinguished by their rich spectra of organic molecular emission lines. We aim to utilize hig…
Abundance anomalies in low mass field mergers as evidence of a merger origin for the second generation stars in globular clusters
Valery Kravtsov, Sami Dib, Francisco A. Calderon
The canonical formation of second-generation (G2) stars in globular clusters (GCs) from gas enriched and ejected by G1 (primordial) polluters faces substantial challenges, i.e. (i)…
Feedback regulated star formation: II. dual constraints on the SFE and the age spread of stars in massive clusters
Sami Dib, Julia Gutkin, Wolfgang Brandner +1
We show that the termination of the star formation process by winds from massive stars in protocluster forming clumps imposes dual constraints on the star formation efficiencies (S…
The emergence of the galactic stellar mass function from a non-universal IMF in clusters
Sami Dib, Shantanu Basu
We investigate how a single generation galactic mass function (SGMF) depends on the existence of variations in the initial stellar mass functions (IMF) of stellar clusters. We show…
The ALMA-QUARKS survey: Hot Molecular Cores are a long-standing phenomenon in the evolution of massive protostars
Dezhao Meng, Tie Liu, Jarken Esimbek +34
We present an analysis of the QUARKS survey sample, focusing on protoclusters where Hot Molecular Cores (HMCs, traced by CH3CN(12--11)) and UC HII regions (traced by H30α/H40α) c…
The ALMA-ATOMS-QUARKS survey: Resolving a chemically rich massive protostellar outflow
Jia-Hang Zou, Tie Liu, Fengwei Xu +19
We present a comprehensive study on the physical and chemical structures of a chemically rich bipolar outflow in a high-mass star forming region IRAS 162724837 (SDC335), utilizi…
Magneto-thermal condensation modes including the effects of charged dust particles
Mohsen Shadmehri, Sami Dib
We study thermal instability in a magnetized and partially ionized plasma with charged dust particles. Our linear analysis shows that the growth rate of the unstable modes in the p…
The massive relic galaxy NGC 1277 is dark matter deficient. From dynamical models of integral-field stellar kinematics out to five effective radii
Sébastien Comerón, Ignacio Trujillo, Michele Cappellari +7
According to the CDM cosmology, present-day galaxies with stellar masses should contain a sizable fraction of dark matter within their stellar b…
Feedback Regulated Star Formation: Implications for the Kennicutt-Schmidt Law
Sami Dib
We derive a metallicity dependent relation between the surface density of the star formation rate (Sigma_{SFR}) and the gas surface density (Sigma_{g}) in a feedback regulated mode…
Star formation activity and the spatial distribution and mass segregation of dense cores in the early phases of star formation
Sami Dib, Thomas Henning
We examine the spatial distribution and mass segregation of dense molecular cloud cores in a number of nearby star forming regions that span about four orders of magnitude in star…
Testing the universality of the IMF with Bayesian statistics: young clusters
Sami Dib
The universality of the stellar initial mass function (IMF) is tested using Bayesian statistics with a sample of eight young Galactic stellar clusters (IC 348, ONC, NGC 2024, NGC 6…
Assessing the accuracy of the star formation rate measurements by direct star count in molecular clouds
Sami Dib, Jian Wen Zhou, Sébastien Comerón +8
Star formation estimates based on the counting of YSOs is commonly applied to nearby star-forming regions in the Galaxy. With this method, the SFRs are measured using the counts of…
Self-similar cluster structures in massive star-forming regions: Isolated evolution from clumps to embedded clusters
J. W. Zhou, Pavel Kroupa, Sami Dib
We used the dendrogram algorithm to decompose the surface density distributions of stars into hierarchical structures. These structures were tied to the multiscale structures of st…
Magnetic field structure around cores with very low luminosity objects
A. Soam, G. Maheswar, Chang Won Lee +4
[Abridged] We carried out optical polarimetry of five dense cores, (IRAM 04191, L1521F, L328, L673-7, and L1014) which are found to harbour VeLLO. This study was conducted mainly t…
Star formation efficiency as a function of metallicity: from star clusters to galaxies
Sami Dib, Laurent Piau, Subhanjoy Mohanty +1
We explore how the star formation efficiency in a protocluster clump is regulated by metallicity dependent stellar winds from the newly formed massive OB stars (Mstar >5 Msol). The…
An examination of large-scale galactic effects on molecular cloud properties in NGC 628 : The significant impact of tidal effects from neighboring material on the evolution of molecular clouds
J. W. Zhou, Sami Dib
The physical factors that influence the development of molecular cloud's density contrast are connected to those that affect star formation in the galaxy. For NGC 628 (M74), the pr…
Metal-THINGS: gas metallicity gradients in nearby galaxies
Guillermo Valé, Maritza A. Lara-López, Mabel Valerdi +13
This paper explores the gas metallicity gradients in a sample of 25 nearby galaxies using new Integral Field Spectroscopy observations from the Metal-THINGS survey. We derive and s…
Physical properties and chemical composition of the cores in the California molecular cloud
Guo-Yin Zhang, Jin-Long Xu, A. I. Vasyunin +13
We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star fo…