Abstract
We have selected galaxies with very high levels of H α emission (EQW(H α) >700 Å.) in their central regions from the final data release of the MaNGA survey. Our study focuses on 14 very well-resolved nearby galaxies with stellar masses in the range 9.5 < log M∗/(M☉) < 11.5. We investigate a variety of procedures for selecting galaxy regions that are likely to harbour excess populations of young massive stars, finding that selection in the 2D space of extinction-corrected H α EQW and [S III]/[S II] line ratio produces the best results. By comparing stacked spectra covering these regions with stacked spectra covering normal starburst regions with 100 Å<EQW(H α) <200 Å, we obtain the following main results: (1) Clear signatures of excess Wolf–Rayet stars are found in half of the H α excess regions, (2) galaxy regions containing excess Wolf–Rayet stars are more often associated with the presence of high-ionization emission lines characteristic of accreting black holes. Excess [Ne III] is detected in 4 out of 8 of the WR regions and there are tentative [Fe X] detections in 2 galaxies. (3) Regions of the galaxy with excess Wolf–Rayet stars are located where the interstellar medium has larger ionized gas turbulent velocities and higher neutral gas overdensities. We make a first attempt to constrain changes in the high-mass end of the stellar initial mass function (IMF) using the HR-pyPopStar evolutionary population synthesis models that include high-wavelength-resolution theoretical atmosphere libraries for Wolf–Rayet stars.
Original language | English |
---|---|
Pages (from-to) | 150-170 |
Number of pages | 21 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 527 |
Issue number | 1 |
Early online date | 12 Oct 2023 |
DOIs | |
Publication status | Published - 1 Jan 2024 |
Keywords
- active
- bulges-galaxies
- galaxies
- nuclei-galaxies
- star formation-galaxies
- stellar content-stars
- Wolf–Rayet-galaxies