Gas-rich dwarf galaxy multiples in the Apertif H I survey
Context. Dwarf-dwarf galaxy encounters are a key aspect of galaxy evolution as they can ignite or temporarily suppress star formation in dwarfs and can lead to dwarf mergers. However, the frequency and impact of dwarf encounters remain poorly constrained due to limitations in spectroscopic studies, such as surface-brightness incompleteness in optical studies and poor spatial resolution in single-dish neutral hydrogen (H I ) surveys. Aims. We aim to quantify the frequency of isolated gas-rich dwarf galaxy multiples using the untargeted, interferometric Apertif H I survey and study the impact of the interaction on star formation rates of galaxies as a function of the on-sky separation. Methods. Our parent dwarf sample consists of 2481 gas-rich galaxies with stellar masses in the range ∼10 6 < M ⋆ / M ⊙ ≲ 5 × 10 9 , for which we identified close companions based on projected separation ( r p ) and systemic velocity difference (|Δ V sys |). We explored both constant thresholds for r p and |Δ V sys | corresponding to 150 kpc and 150 km s −1 on all galaxies in our sample as well as mass-dependent thresholds based on a stellar-to-halo mass relation. Results. We find the average number of companions per dwarf in our sample to be 13% (20%) when considering mass-dependent (constant) thresholds. We find that the frequency (∼11.6%) of dwarf companions in the stellar mass regime of 2 × 10 8 < M ⋆ / M ⊙ < 5 × 10 9 is three times higher than previously determined from optical spectroscopic studies, highlighting the power of H I for finding dwarf multiples. Furthermore, we find evidence for an increase in star formation rates (SFRs) of close dwarf galaxy pairs of galaxies with similar stellar masses.
Authors
- S. Sánchez–Expósito (ORCID: https://orcid.org/0000-0002-7510-7633)
- K.M. Hess
- Antonino Marasco (ORCID: https://orcid.org/0000-0002-5655-6054)
- R. Morganti
- Elizabeth A. K. Adams (ORCID: https://orcid.org/0000-0002-9798-5111)
- D. M. Lucero (ORCID: https://orcid.org/0000-0002-8799-3054)
- Barbara Šiljeg (ORCID: https://orcid.org/0000-0001-5391-8286)
- Julián Garrido (ORCID: https://orcid.org/0000-0002-6696-4772)
- Helga Dénes (ORCID: https://orcid.org/0000-0002-9214-8613)
- J. M. van der Hulst (ORCID: https://orcid.org/0000-0002-9316-763X)
- Filippo Fraternali (ORCID: https://orcid.org/0000-0002-0447-3230)
Institutions
- University of Groningen (NL)
- Universidad Yachay Tech (EC)
- Astronomical Institute of the Slovak Academy of Sciences (SK)
- Astronomical Observatory (RS)
- Instituto de Astrofísica de Andalucía (ES)
- Osservatorio Astronomico di Padova (IT)
- Chalmers University of Technology (SE)
- Virginia Tech (US)
- Netherlands Institute for Radio Astronomy (NL)
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2025-10-16
- DOI
- https://doi.org/10.1051/0004-6361/202554841
- Primary Topic
- Astronomy and Astrophysical Research
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- Smithsonian Institution
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- California Institute of Technology
- Johns Hopkins University
- Space Telescope Science Institute
- Ministerio de Ciencia, Innovación y Universidades
- European Commission
- Queen's University Belfast
- Durham University
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Queen's University
- Ministerio de Ciencia e Innovación
- National Central University
- Eötvös Loránd Tudományegyetem
- Junta de Andalucía
- ASTRON
- Instituto de Astrofísica de Andalucía
- Max-Planck-Institut für Astronomie
- Jet Propulsion Laboratory
- University of California, Los Angeles
- Smithsonian Astrophysical Observatory
- Science Mission Directorate
- HORIZON EUROPE Framework Programme
- European Regional Development Fund
- Agencia Estatal de Investigación
- Planetary Science Division