Nuclear star cluster formation in star-forming dwarf galaxies

Autor(en)

Katja Fahrion, Teodora-Elena Bulichi, Michael Hilker, Ryan Leaman, Mariya Lyubenova, Oliver Müller, Nadine Neumayer, Francesca Pinna, Marina Rejkuba, Glenn van de Ven

Abstrakt

Nuclear star clusters (NSCs) are massive star clusters found in all types of galaxies from dwarfs to massive galaxies. Recent studies show that while low-mass NSCs in dwarf galaxies (M_gal < 10⁹ M_⊙) form predominantly out of the merger of globular clusters (GCs), high-mass NSCs in massive galaxies have assembled most of their mass through central enriched star formation. So far, these results of a transition in the dominant NSC formation channel have been based on studies of early-type galaxies and massive late-type galaxies. Here, we present the first spectroscopic analysis of a sample of nine nucleated late-type dwarf galaxies with the aim of identifying the dominant NSC formation pathway. We use integral-field spectroscopy data obtained with the Multi Unit Spectroscopic Explorer (MUSE) instrument to analyse the ages, metallicities, star formation histories, and star formation rates of the NSCs and their surroundings. Our sample includes galaxies with stellar masses M_gal = 10⁷ − 10⁹ M_⊙ and NSC masses M_NSC = 6 × 10⁴ − 6 × 10⁶ M_⊙. Although all NSC spectra show emission lines, this emission is not always connected to star formation within the NSC, but rather to other regions along the line of sight. The NSC star formation histories reveal that metal-poor and old populations dominate the stellar populations in five NSCs, possibly stemming from the inspiral of GCs. The NSCs of the most massive galaxies in our sample show significant contributions from young and enriched populations that indicate additional mass growth through central star formation. Our results support previous findings of a transition in the dominant NSC formation channel with galaxy mass, showing that the NSCs in low-mass galaxies predominantly grow through the inspiral of GCs, while central star formation can contribute to NSC growth in more massive galaxies.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

European Space Agency (ESA), University of Edinburgh, European Southern Observatory (Germany), École polytechnique fédérale de Lausanne, Max-Planck-Institut für Astronomie

Journal

Astronomy & Astrophysics

Band

667

Anzahl der Seiten

13

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/202244932

Publikationsdatum

11-2022

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/59725e97-ea9c-4d06-8e60-e10fac2e9b0b