Query : 2021ApJ...923..120L

2021ApJ...923..120L - Astrophys. J., 923, 120-120 (2021/December-2)

Wolf-Rayet galaxies in SDSS-IV MaNGA. II. Metallicity dependence of the high-mass slope of the stellar initial mass function.

LIANG F.-H., LI C., LI N., ZHOU S., YAN R., MO H. and ZHANG W.

Abstract (from CDS):

As hosts of living high-mass stars, Wolf-Rayet (WR) regions or WR galaxies are ideal objects for constraining the high-mass end of the stellar initial mass function (IMF). We construct a large sample of 910 WR galaxies/regions that cover a wide range of stellar metallicity (from Z ∼ 0.001 to 0.03) by combining three catalogs of WR galaxies/regions previously selected from the SDSS and SDSS-IV/MaNGA surveys. We measure the equivalent widths of the WR blue bump at ∼4650 Å for each spectrum. They are compared with predictions from stellar evolutionary models Starburst99 and BPASS, with different IMF assumptions (high-mass slope α of the IMF ranging from 1.0 to 3.3). Both singular evolution and binary evolution are considered. We also use a Bayesian inference code to perform full spectral fitting to WR spectra with stellar population spectra from BPASS as fitting templates. We then make a model selection among different α assumptions based on Bayesian evidence. These analyses have consistently led to a positive correlation of the IMF high-mass slope α with stellar metallicity Z, i.e., with a steeper IMF (more bottom-heavy) at higher metallicities. Specifically, an IMF with α = 1.00 is preferred at the lowest metallicity (Z ∼ 0.001), and an Salpeter or even steeper IMF is preferred at the highest metallicity (Z ∼ 0.03). These conclusions hold even when binary population models are adopted.

Abstract Copyright: © 2021. The American Astronomical Society. All rights reserved.

Journal keyword(s): Wolf-Rayet stars - Starburst galaxies - Galaxy evolution - Stellar evolutionary models - Initial mass function - Star formation

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 1407 GiG 03 40 11.904 -18 34 49.36   10.64 9.67 9.13   ~ 569 1
2 IC 3720 GiC 12 44 46.522 +12 04 00.81   16.0     14.1 ~ 43 0

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