Wolf-Rayet Galaxies in the Sloan Digital Sky Survey: the metallicity dependence of the initial mass function

Abstract

We use a large sample of 174 Wolf-Rayet (WR) galaxies drawn from the Sloan Digital Sky Survey to study whether and how the slope of the stellar initial mass function depends on metallicity. We calculate for each object its oxygen abundance according to which we divide our sample into four metallicity subsamples. For each subsample, we then measure three quantities: the equivalent width of \hb emission line, the equivalent width of WR bump around 4650Å, and the WR bump-to-\hb intensity ratio, and compare to the predictions of the same quantities by evolutionary synthesis models of Schaerer & Vacca. Such comparisons lead to a clear dependence of the slope of initial mass function ($\alpha$) on metallicity in that galaxies at higher metallicities tend to have steeper initial mass functions, with the slope index ranging from $\alpha \sim$1.00 for the lowest metallicity of $Z=0.001$ to $\alpha \sim$3.30 for the highest metallicity $Z=0.02$. We have carefully examined the possible sources of systematic error either in models or in our observational measurements and shown that these sources do not change this result.

arXiv comment12 pages, 6 figures, ApJ accepted

References in corpus (28)

• Stellar population synthesis at the resolution of 2003
• The Sloan Digital Sky Survey: Technical Summary
• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• The Host Galaxies of AGN
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• A Simple Model for the Absorption of Starlight by Dust in Galaxies
• The Sloan Digital Sky Survey Photometric Camera
• The u'g'r'i'z' Standard Star Network
• Astrometric Calibration of the Sloan Digital Sky Survey
• The Third Data Release of the Sloan Digital Sky Survey
• A photometricity and extinction monitor at the Apache Point Observatory
• An Efficient Algorithm for Positioning Tiles in the Sloan Digital Sky Survey
• Heavy element abundances in blue compact galaxies
• Spectroscopy of Outlying H II Regions in Spiral Galaxies: Abundances and Radial Gradients
• New Models for Wolf-Rayet and O Star Populations in Young Starbursts
• A Spectroscopic Study of a Large Sample of Wolf-Rayet Galaxies
• Reduced Wolf-Rayet Line Luminosities at Low Metallicity
• Spectroscopic study of blue compact galaxies V. oxygen abundance and the metallicity-luminosity relation
• Ensemble Learning Independent Component Analysis of Normal Galaxy Spectra
• Partially obscured quasars in the Sloan Digital Sky Survey Early Data Release
• Balmer and Paschen jump temperature determinations in low-metallicity emission-line galaxies
• Spectroscopic Study of Blue Compact Galaxies II. Spectral Analysis and Correlations
• Abundance patterns in the low-metallicity emission-line galaxies from the Early Data Release of the Sloan Digital Sky Survey
• Empirical modeling of the stellar spectrum of galaxies
• Massive Star Populations in Wolf-Rayet Galaxies
• New Wolf-Rayet Galaxies with Detection of WC Stars

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• Galaxies with Wolf-Rayet signatures in the low-redshift Universe - A survey using the Sloan Digital Sky Survey
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• Broad Line Emission in Low-Metallicity Blue Compact Dwarf Galaxies: Evidence for Stellar Wind, Supernova and Possible AGN Activity
• Massive star formation in Wolf-Rayet galaxies. III: Analysis of the O and WR populations
• Massive stars formed in atomic hydrogen reservoirs: HI observations of gamma-ray burst host galaxies
• Massive star formation in Wolf-Rayet galaxies: II. Optical spectroscopy results
• SDSS-IV MaNGA: Stellar initial mass function variation inferred from Bayesian analysis of the integral field spectroscopy of early type galaxies
• Massive star formation in Wolf-Rayet galaxies: I. Optical and NIR photometric results
• Dissection of Halpha Emitters : Low-z Analogs of z>4 Star-Forming Galaxies
• Wolf-Rayet galaxies in SDSS-IV MaNGA. I. Catalog construction and sample properties
• Photometric and spectroscopic studies of star-forming regions within Wolf-Rayet galaxies
• The galaxy-wide stellar initial mass function in the presence of cluster-to-cluster IMF variations
• Wolf-Rayet galaxies in SDSS-IV MaNGA. II. Metallicity dependence of the high-mass slope of the stellar initial mass function
• Are Wolf-Rayet stars able to pollute the interstellar medium of galaxies? Results from the integral field spectroscopy
• Halpha imaging survey of Wolf-Rayet galaxies: morphologies and star formation rates
• Devasthal Fast Optical Telescope observations of Wolf-Rayet dwarf galaxy Mrk 996
• Witnessing a Transformation to Blue-cored Dwarf Early-type Galaxies in Filaments and the Cluster Outskirts: Gas-phase Abundances and Internal Kinematics Perspectives
• Clustering Property of Wolf-Rayet Galaxies in the SDSS
• Massive stars in the nuclei and arms of spirals