On the initial binary population for star cluster simulations

Abstract

Colour-magnitude diagrams (CMDs) are powerful tools that might be used to infer stellar properties in globular clusters (GCs), for example, the binary fraction and their mass ratio ($q$) distribution. In the past few years, observations have revealed that q distributions of GC main-sequence (MS) binaries are generally flat, and a distribution characterized by a strong increase towards q $\approx$ 1 is not typical in GCs. In numerical simulations of GC evolution with the initial binary population (IBP) described by Kroupa, synthetic CMD colour distributions exhibit a peak associated with binaries that have q $\approx$ 1. While the Kroupa IBP reproduces binary properties in star-forming regions, clusters and the Galactic field, the peak in the q distribution towards q $\approx$ 1 observed for GC simulations is not consistent with distributions derived from observations. The objective of this paper is to refine and further improve the physical formulation of pre-main-sequence eigenevolution proposed by Kroupa in order to achieve CMD colour distributions of simulated GC models similar to those observed in real GCs, and to get a similarly good agreement with binary properties for late-type binaries in the Galactic field. We present in this paper a modified Kroupa IBP, in which early-type stars follow observational distributions, and late-type stars are generated according to slightly modified pre-main-sequence eigenevolution prescriptions. Our modifications not only lead to a qualitatively good agreement with respect to long-term observations of late-type binaries in the Galactic field, but also resolve the above-mentioned problem related to binary distributions in GC models.

18 pages, 10 figures, 4 tables; accepted for publication in MNRAS

References in corpus (48)

• Embedded Clusters in Molecular Clouds
• Binary interaction dominates the evolution of massive stars
• Evolution of binary stars and the effect of tides on binary populations
• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Comprehensive analytic formulae for stellar evolution as a function of mass and metallicity
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• The ACS Survey of Galactic Globular Clusters. XII. Photometric Binaries along the Main-Sequence
• The Formation of a Bound Star Cluster: From the Orion Nebula Cluster to the Pleiades
• Inverse Dynamical Population Synthesis and Star Formation
• The Spatial Distribution of Star Formation in the Solar Neighbourhood: Do all stars form in clusters?
• Stellar Collisions During Binary-Binary and Binary-Single Star Interactions
• The Dynamical Properties of Stellar Systems in the Galactic Disc
• HST color-magnitude diagrams of 74 galactic globular clusters in the HST F439W and F555W bands
• The DRAGON simulations: globular cluster evolution with a million stars
• MOCCA Code for Star Cluster Simulations - IV. A new Scenario for Intermediate Mass Black Hole Formation in Globular Clusters
• The Time Scale of Escape from Star Clusters
• Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations
• The fraction of binary systems in the core of thirteen low-density Galactic globular clusters
• MOCCA Code for Star Cluster Simulations - II. Comparison with N-body Simulations
• Star Cluster Evolution, Dynamical Age Estimation and the Kinematical Signature of Star Formation
• MOCCA code for star cluster simulations - I. Blue Stragglers, first results
• Dynamical ejections of massive stars from young star clusters under diverse initial conditions
• Limits on the primordial stellar multiplicity
• Binaries Like to be Twins: Implications for Doubly Degenerate Binaries, the Supernova Ia Rate and Other Interacting Binaries
• Lucky Imaging survey for southern M dwarf binaries
• Dense Stellar Populations: Initial Conditions
• Dependency of dynamical ejections of O stars on the masses of very young star clusters
• Exploring the consequences of pairing algorithms for binary stars
• The evolution of embedded star clusters
• An analytical description of the evolution of binary orbital-parameter distributions in N-body computations of star clusters
• The bound fraction of young star clusters
• How can young massive clusters reach their present-day sizes?
• Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations
• The physics and modes of star cluster formation: observations
• The state of globular clusters at birth II: primordial binaries
• Binaries in the field: fossils of the star formation process?
• Testing the universality of star formation - II. Comparing separation distributions of nearby star-forming regions and the field
• What a Local Sample of Spectroscopic Binaries can tell us about the Field-Binary Population
• Embedded Binaries and Their Dense Cores
• Mass Evaporation Rate of Globular Clusters in a Strong Tidal Field
• Multiplicity and period distribution of Population II field stars in solar vicinity
• MOCCA-SURVEY Database I: Is NGC 6535 a Dark Star Cluster Harboring an IMBH?
• MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- III. Cataclysmic variables -- Implications of model assumptions
• Physical properties of seven binary and higher-order multiple OB systems
• The universality hypothesis: binary and stellar populations in star clusters and galaxies
• M-dwarf binaries as tracers of star and brown dwarf formation
• Pre-mainsequence stellar evolution in N-body models
• COCOA Code for Creating Mock Observations of Star Cluster Models

Cited by in corpus (43)

• Measuring the binary black hole mass spectrum with an astrophysically motivated parameterization
• A stellar census in globular clusters with MUSE: Binaries in NGC 3201
• The origin of the first neutron star -- neutron star merger
• Binary Black Hole Mergers from Globular Clusters: the Impact of Globular Cluster Properties
• The possible role of stellar mergers for the formation of multiple stellar populations in globular clusters
• 3D Morphology of Open Clusters in the Solar Neighborhood with Gaia EDR3: its Relation to Cluster Dynamics
• Testing Gravity with wide binary stars like $\alpha$ Centauri
• Preparing the next gravitational million-body simulations: Evolution of single and binary stars in Nbody6++GPU, MOCCA and McLuster
• Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster
• Complete ejection of OB stars from very young star clusters and the formation of multiple populations
• White Dwarf Subsystems in Core-Collapsed Globular Clusters
• MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- IV. cataclysmic variables -- properties of bright and faint populations
• MOCCA Survey Database I: Dissolution of tidally filling star clusters harbouring BH subsystems
• MOCCA-SURVEY Database I: Assessing GW kick retention fractions for BH-BH mergers in globular clusters
• In Search of the Thermal Eccentricity Distribution
• Do star clusters form in a completely mass-segregated way?
• The multiplicity fraction in 202 open clusters from Gaia
• Dissecting the stellar content of Leo I: a dwarf irregular caught in transition
• Integrated-light analyses vs. colour-magnitude diagrams - II. Leo A, an extremely young dwarf in the Local Group
• The impact of primordial binary on the dynamical evolution of intermediate massive star clusters
• Very massive stars in not so massive clusters
• MOCCA: Dynamics and evolution of binary stars of multiple stellar populations in tidally filling and underfilling globular star clusters
• Finding Black Holes with Black Boxes -- Using Machine Learning to Identify Globular Clusters with Black Hole Subsystems
• Dynamical equivalence, the origin of the Galactic field stellar and binary population, and the initial radius--mass relation of embedded clusters
• Magnetic dynamos in white dwarfs -- I. Explaining the dearth of bright intermediate polars in globular clusters
• On the absence of symbiotic stars in globular clusters
• A Monte Carlo study of early gas expulsion and evolution of star clusters: new simulations with the MOCCA code in the AMUSE framework
• BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population
• On the origin of the split main sequences of the young massive cluster NGC 1856
• Primordial mass segregation of star clusters with primordial binaries
• The initial mass function of stars and the star-formation rates of galaxies
• A possible solution to the Milky Way's binary-deficient retrograde stellar population. Evidence that $\omega$ Centauri has formed in an extreme starburst
• COCOA Code for Creating Mock Observations of Star Cluster Models
• On the dynamical evolution of Cepheid multiplicity in star clusters and its implications for B-star multiplicity at birth
• The mass distribution of stellar mergers: A new scenario for several FS CMa stars
• Effects of physical conditions on the stellar initial mass function: The low-metallicity star-forming region Sh 2-209
• MOCCA: Effects of pristine gas accretion and cluster migration on globular cluster evolution, global parameters, and multiple stellar populations
• The Origin of Young Stellar Populations in NGC 1783: Accretion of External Stars
• Multiple stellar populations in MOCCA globular cluster models: Transient spatial over-concentration of pristine red giant stars driven by strong dynamical encounters
• Compact object populations over cosmic time I. BOSSA: a Binary Object environment-Sensitive Sampling Algorithm
• Tidal Synchronization of Binaries in Pleiades
• Double white dwarf binary population in MOCCA star clusters -- Comparisons with observations of close and wide binaries
• Are most Cataclysmic Variables in Globular Clusters dynamically formed?