Abstract
Tidal dwarf galaxies (TDGs) form in the debris of galaxy mergers, making them ideal testbeds for investigating star formation in an extreme environment. We present radio continuum EVLA observations spanning 1–2 GHz of the interacting system Arp 94, which contains the TDG J1023+1952. We detect extended radio continuum emission from the disc of the TDG’s putative parent galaxy, the spiral NGC 3227. The TDG lies in front of the spiral disc, partially overlapping in projection. This challenging alignment complicates the separation of the respective contributions of radio emission from the TDG and disc. However, we show that the radio continuum appears more prominent around the TDG’s location, suggesting the detection of emission from the TDG. Quantifying this argument, we derive an upper limit of 2.2 mJy for the whole TDG’s emission. Our derived inband spectral index map of the system generally shows the expected behaviour of combined thermal and synchrotron radio emission in a galaxy disc, except for a region at the periphery of the disc and the TDG with a flat spectrum (spectral index ∼−0.4) unrelated to regions with high H α emission. We speculate that at this location – which coincides with the intersection of faint tidal tails – the collision of gas clouds produces shocks which re-accelerate cosmic ray electrons, and thereby enhance the radio emission. Overall, this study provides new insights about the Arp 94 system and expands the sample of TDGs studied at radio frequencies, with only two confirmed detections so far.
Original language | English |
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Pages (from-to) | 496-505 |
Number of pages | 10 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 532 |
Issue number | 1 |
Early online date | 12 Jun 2024 |
DOIs | |
Publication status | Published - 31 Jul 2024 |
Data Availability Statement
Raw data from the EVLA is publicly available in the VLA Archive (https://data.nrao.edu/portal) under project code 13A-066. Reduced data will be shared on request to the corresponding author.Funding
We thank the anonymous referee for the detailed comments which helped us improve the manuscript. We wish to thank Prof. Elias Brinks for useful discussions and detailed comments on the manuscript. BMMC acknowledges funding from the Instituto de Astrof\u00EDsica de Canarias under the IAC 2021 International Scholarships Program. UL acknowledges support by the research project PID2020-114414GB-I00 financed by the Spanish Ministerio de Ciencia e Innovaci\u00F3n(MCIN/AEI/10.13039/501100011033), and the Junta de Andaluc\u00EDa (Spain) grant FQM108. MQ acknowledges support from the Spanish grant PID2022-138560NBI00, funded by the Spanish Ministerio de Ciencia e Innovaci\u00F3n and the European Regional Development Funds (FEDER)(MCIN/AEI/10.13039/501100011033/FEDER, EU). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research made use of the Cube Analysis and Rendering Tool for Astronomy (CARTA; Comrie et al. 2018). This work made use of the following PYTHON libraries: ASTROPY (The Astropy Collaboration 2022), MATPLOTLIB (Hunter 2007), and NUMPY (Harris et al. 2020). We thank the anonymous referee for the detailed comments which helped us improve the manuscript. We wish to thank Prof. Elias Brinks for useful discussions and detailed comments on the manuscript. BMMC acknowledges funding from the Instituto de Astrof\u00EDsica de Canarias under the IAC 2021 International Scholarships Program. UL acknowledges support by the research project PID2020-114414GB-I00 financed by the Spanish Ministerio de Ciencia e Innovaci\u00F3n (MCIN/AEI/10.13039/501100011033), and the Junta de Andaluc\u00EDa (Spain) grant FQM108. MQ acknowledges support from the Spanish grant PID2022-138560NB-I00, funded by the Spanish Ministerio de Ciencia e Innovaci\u00F3n and the European Regional Development Funds (FEDER) (MCIN/AEI/10.13039/501100011033/FEDER, EU). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research made use of the Cube Analysis and Rendering Tool for Astronomy ( carta ; Comrie et al. ). This work made use of the following python libraries: Astropy (The Astropy Collaboration ), Matplotlib (Hunter ), and numpy (Harris et al. ).
Funders | Funder number |
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EU | |
European Regional Development Fund | |
Junta de Andalucia | PID2022-138560NB-I00, FQM108 |
Junta de Andalucia | |
Instituto de Astrofísica de Canarias (IAC) | PID2020-114414GB-I00 |
Instituto de Astrofísica de Canarias (IAC) | |
Ministerio de Ciencia e Innovacion | MCIN/AEI/10.13039/501100011033 |
Ministerio de Ciencia e Innovacion | |
FEDER | MCIN/AEI/10.13039/501100011033/FEDER |
CARTA | 2022 |
Keywords
- galaxies: dwarf
- galaxies: interactions
- galaxies: star formation
- radio continuum: ISM
- radio continuum: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science