Testing the universality of the IMF with Bayesian statistics: young clusters

Abstract

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 6611, NGC 2264, $\rho$ Ophiuchi, Chameleon I, and Taurus). We infer the posterior probability distribution function (pPDF) of the IMF parameters when the likelihood function is described by a tapered power law function, a lognormal distribution at low masses coupled to a power law at higher masses, and a multi-component power law function. The inter-cluster comparison of the pPDFs of the IMF parameters for each likelihood function shows that these distributions do not overlap within the $1\sigma$ uncertainty level. Furthermore, the most probable values of the IMF parameters for most of the clusters deviate substantially from their values for the Galactic field stellar IMF. We also quantify the effects of taking into account the completeness correction as well as the uncertainties on the measured masses. The inclusion of the former affects the inferred pPDFs of the slope of the IMF at the low mass end while considering the latter affects the pPDFs of the slope of the IMF in the intermediate- to high mass regime. As variations are observed in all of the IMF parameters at once and for each of the considered likelihood functions, even for completeness corrected samples, we argue that the observed variations are real and significant, at least for the sample of eight clusters considered in this work. The results presented here clearly show that the IMF is not universal.

arXiv commentaccepted to MNRAS

References in corpus (94)

• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• A Census of the Young Cluster IC 348
• Early Star Formation and the Evolution of the Stellar Initial Mass Function in Galaxies
• The Luminosity & Mass Function of the Trapezium Cluster: From B stars to the Deuterium Burning Limit
• The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: II. The Field
• The initial mass function : from Salpeter 1955 to 2005
• Constraints on the Stellar/Sub-stellar Mass Function in the Inner Orion Nebula Cluster
• The Stellar Population of the Chamaeleon I Star-Forming Region
• The Taurus Spitzer Survey: New Candidate Taurus Members Selected Using Sensitive Mid-Infrared Photometry
• The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Young Clusters
• Low-Mass Star Formation and the Initial Mass Function in the Rho Ophiuchi Cloud Core
• New Brown Dwarfs and an Updated Initial Mass Function in Taurus
• A Census of the Chamaeleon I Star-Forming Region
• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster
• The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Taurus
• New Low-Mass Members of the Taurus Star-Forming Region
• An Infrared/X-ray Survey for New Members of the Taurus Star-Forming Region
• The Initial Mass Function of the Massive Star-forming Region NGC 3603 from Near-Infrared Adaptive Optics observations
• Meeting the Cool Neighbors VIII: A preliminary 20-parsec census from the NLTT catalogue
• The Substellar Mass Function in sigma Orionis
• The Initial Mass Function of the Orion Nebula Cluster across the H-burning limit
• Numerical biases on IMF determinations created by binning
• The massive star initial mass function of the Arches cluster
• On the function describing the stellar initial mass function
• A Study of the Luminosity and Mass Functions of the Young IC 348 Cluster using FLAMINGOS Wide-Field Near-Infrared Images
• The Star Formation History and Mass Function of the Double Cluster h and Chi Persei
• The secrets of the nearest starburst cluster: II. The present-day mass function in NGC 3603
• A Near-Infrared L Band Survey of the Young Embedded Cluster NGC 2024
• The Low End of the Initial Mass Function in Young LMC Clusters: I. The Case of R136
• The Eta Chamaeleontis Cluster: Origin in the Sco-Cen OB Association
• From Stars to Super-planets: the Low-Mass IMF in the Young Cluster IC348
• The Substellar Mass Function: A Bayesian Approach
• Evidence for a Turnover in the IMF of Low Mass Stars and Sub-stellar Objects: Analysis from an Ensemble of Young Clusters
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region. I. Enlarging the census down to the planetary mass domain in Collinder 69
• On the Constancy of the Characteristic Mass of Young Stars
• Deuterium-burning in substellar objects
• Brown dwarfs and very low mass stars in the Hyades cluster : a dynamically evolved mass function
• Mass segregation and elongation of the starburst cluster Westerlund 1
• The Stellar Initial Mass Function
• Orion Revisited - I. The massive cluster in front of the Orion Nebula Cluster
• The Star Formation Region NGC 6530: distance, ages and Initial Mass Function
• The Origin of the Arches Stellar Cluster Mass Function
• Mass functions and structure of the young open cluster NGC\,6611
• Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses
• Spectroscopy of new brown dwarf members of rho Ophiuchi and an updated initial mass function
• On the temporal evolution of the stellar mass function in Galactic clusters
• Substellar Objects in Nearby Young Clusters (SONYC): The bottom of the Initial Mass Function in NGC1333
• The Initial Mass Function and Disk Frequency of the Rho Ophiuchi Cloud: An Extinction-Limited Sample
• Multi-fibre optical spectroscopy of low-mass stars and brown dwarfs in Upper Sco
• An Enhanced Spectroscopic Census of the Orion Nebula Cluster
• Orion revisited. II. The foreground population to Orion A
• Low Mass Stars and Brown Dwarfs in NGC 2024: Constraints on the Substellar Mass Function
• An Initial Mass Function for Individual Stars in Galactic Disks: I. Constraining the Shape of the IMF
• The IMF of stellar clusters: effects of accretion and feedback
• Young T-Dwarf Candidates in IC 348
• The low-mass population of the Rho Ophiuchi molecular cloud
• The Initial Mass Function and Young Brown Dwarf Candidates in NGC 2264. IV. The Initial Mass Function and Star Formation History
• Mass functions and photometric binaries in nine open clusters
• The Arches cluster out to its tidal radius: dynamical mass segregation and the effect of the extinction law on the stellar mass function
• The Pleiades mass function: models versus observations
• The low-mass Initial Mass Function in the young cluster NGC 6611
• A deep photometric survey of the eta Chamaeleontis cluster down to the brown dwarf - planet boundary
• An explanation for the unusual IMF in Taurus
• The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud with Hubble Space Telescope ACS Observations
• X-ray view of IC348 in the light of an updated cluster census
• The Panchromatic Hubble Andromeda Treasury IV. A Probabilistic Approach to Inferring the High Mass Stellar Initial Mass Function and Other Power-law Functions
• On the determination of age and mass functions of stars in young open star clusters from the analysis of their luminosity functions
• Substellar Objects in Nearby Young Clusters (SONYC) II: The Brown Dwarf Population of Rho Ophiuchi
• Substellar Objects in Nearby Young Clusters (SONYC) III: Chamaeleon-I
• Star formation near an obscured AGN: Variations in the initial mass function
• Formation of proto-clusters and star formation within clusters: apparent universality of the initial mass function ?
• Probing the Low Mass Stellar End of the eta Chamaeleontis Cluster
• The IMF of open star clusters with Tycho-2
• The low-mass Initial Mass Function in the Orion Nebula cluster based on HST/NICMOS III imaging
• Brown dwarfs and very low mass stars in the Praesepe open cluster: a dynamically unevolved mass function?
• Two 2MASS-Selected Young Stellar Clusters: Photometry, Spectroscopy, and the IMF
• The initial mass function of the rich young cluster NGC 1818 in the Large Magellanic Cloud
• Circumstellar discs around solar-mass stars in NGC 6611
• Physical parameters of pre-main sequence stars in open clusters
• The IMF and Star Formation History of the Stellar Clusters in the Vela D Cloud
• NGC 7538 : Multiwavelength Study of Stellar Cluster Regions associated with IRS 1-3 and IRS 9 sources
• Optical spectroscopy of X-ray sources in the Taurus molecular cloud: discovery of ten new pre-main sequence stars
• Methane band and Spitzer mid-IR imaging of L and T dwarf candidates in the Pleiades
• The sequence of low and high mass star formation in the young stellar cluster IRAS 19343+2026
• The Initial Mass Function toward the low-mass end in the Large Magellanic Cloud with HST/WFPC2 Observations
• Low Mass Stars and Brown Dwarfs in Praesepe
• The substellar mass function in the central region of the open cluster Praesepe from deep LBT observations
• HST/NICMOS Observations of the Embedded Cluster in NGC 2024: Constraints on the IMF and Binary Fraction
• The Initial Mass Functions of Four Embedded Stellar Clusters
• The Massive Stellar Population in the Young Association LH 95 in the LMC
• On the shape of the mass-function of dense clumps in the Hi-GAL fields. II. Using Bayesian inference to study the clump mass function
• IMF from infrared photometry of young stellar clusters in Taurus-Auriga and Orion

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