Stellar initial mass function in the 100-pc solar neighbourhood

Abstract

The stellar initial mass function (IMF) is among the most fundamental distributions in astrophysics, defined as the mass spectrum of stars produced in a single star-formation event. Even in the solar neighbourhood, where measurements can be conducted via star counting, disentangling the IMF from observational effects remains challenging. In this work we introduce a new parametrisation of the stellar IMF in the 100-pc solar neighbourhood, leveraging the high-precision astrometric and photometric data from \textsl{Gaia} DR3: we model the colour-magnitude diagram of the field star population while accounting for observational uncertainties, Malmquist bias, Lutz-Kelker bias, variations in the mass-luminosity relation arising from metallicity differences, and the effects of unresolved binaries. In particular, we synthesise the binary population with a process imitating the dynamical evolution observed in star clusters to enforce that all components are drawn from the same IMF, while simultaneously recovering the observed present-day mass-ratio distribution. We determine an averaged stellar IMF over $0.25<m<1.0M_{\odot }$ that aligns with canonical IMFs but achieves significantly tighter constraints: ${\alpha }_1=0.75_{-0.04}^{+0.06}$, ${\alpha }_2=2.07_{-0.03}^{+0.04}$, and a break point at $m_{\mathrm{break}}=0.40_{-0.01}^{+0.01}$ ${\mathrm{M}}_{\odot }$. Our inference also yields an averaged binary fraction over $0.25<m<1.0M_{\odot }$ of approximately 26\%, and constrains the \textsl{Gaia} DR3 angular resolution to $1.11_{-0.08}^{+0.11}$ arcsec. We also provide the $\xi$-parameter for our IMF, which is $0.5070_{-0.0096}^{+0.0068}$, to facilitate direct comparison with other IMF determinations.

Accepted for publication in MNRAS

References in corpus (56)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 3: Summary of the content and survey properties
• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• Stellar Multiplicity
• Mind your Ps and Qs: the Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• The Galactic disk mass function: reconciliation of the HST and nearby determinations
• Gaia Early Data Release 3: Photometric content and validation
• Improving PARSEC models for very low mass stars
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: II. The Field
• How to Constrain Your M dwarf II: the mass-luminosity-metallicity relation from 0.075 to 0.70$M_{\odot }$
• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Gravitational fragmentation in turbulent primordial gas and the initial mass function of Population III stars
• Gaia Data Release 3: Stellar multiplicity, a teaser for the hidden treasure
• The stellar and sub-stellar IMF of simple and composite populations
• The Effect of Stellar Rotation on Colour-Magnitude Diagrams: On the apparent presence of multiple populations in intermediate age stellar clusters
• Constraining the thermally-pulsing asymptotic giant branch phase with resolved stellar populations in the Small Magellanic Cloud
• The Variation of Integrated Star IMFs among Galaxies
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• A parsec-scale Galactic 3D dust map out to 1.25 kpc from the Sun
• Numerical biases on IMF determinations created by binning
• PeTar: a high-performance N-body code for modeling massive collisional stellar systems
• 3D mapping of young stars in the solar neighbourhood with Gaia DR2
• Discovery of an equal-mass "twin" binary population reaching 1000+ AU separations
• The Jeans mass and the origin of the knee in the IMF
• The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: I. The Calibration Region
• On the origin of the distribution of binary-star periods
• An analytical description of the evolution of binary orbital-parameter distributions in N-body computations of star clusters
• An empirical model of the Gaia DR3 selection function
• Stellar Initial Mass Function Varies with Metallicities and Time
• The Necessity of Feedback Physics in Setting the Peak of the Initial Mass Function
• The Fornax 3D project: a two-dimensional view of the stellar initial mass function in the massive lenticular galaxy FCC 167
• Mapping the Milky Way with LAMOST I: Method and overview
• The stellar Initial Mass Function of the solar neighbourhood revealed by Gaia
• The binary companion mass ratio distribution: an imprint of the star formation process?
• Selection Functions in Astronomical Data Modeling, with the Space Density of White Dwarfs as Worked Example
• A bottom-heavy initial mass function for the likely-accreted blue-halo stars of the Milky Way
• Smoking Gun of the Dynamical Processing of the Solar-type Field Binary Stars
• Empirical completeness assessment of the Gaia DR2, Pan-STARRS 1 and ASAS-SN-II RR Lyrae catalogues
• BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population
• Internal calibration of LAMOST and Gaia DR3 GSP-Spec stellar abundances
• Dynamical masses across the Hertzsprung-Russell diagram
• Are binary-star populations regionally different? --in memory of Sverre Aarseth--
• Detailed Mapping of the Galactic Disk Structure in the Solar Neighborhood through LAMOST K Dwarfs