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Accepted manuscript

Probing the resolved K-S relation in nearby galaxies: Insights from UVIT and ALMA observations

Published online by Cambridge University Press:  11 September 2025

K Sruthi
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
Sreeja S Kartha
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
Blesson Mathew
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
Ujjwal K.
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
Krishna R Akhil
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
Shankar Ray
Affiliation:
Centre of Excellence in Astronomy and Astrophysics, Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore, India
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Abstract

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This study examines the resolved Kennicutt-Schmidt (rK-S) relation, defined as the connection between the star formation rate surface density (ΣSFR) and the molecular gas mass surface density (ΣH2) in the high-density central regions of three nearby barred spiral galaxies hosting AGN: NGC 1365, NGC 1433, and NGC 1566. Utilising high-resolution archival data from AstroSat/UVIT for UV imaging and Atacama Large Millimetere/submillimetre Array (ALMA) for CO(2-1) molecular gas mapping, we explore recent star formation and gas distribution with a spatial resolution of ∼ 120-132 pc. Our findings reveal a sublinear rK-S law, with slopes ranging from ∼ 0.17 to ∼ 0.71. Notably, NGC 1566 exhibits a robust rK-S relation consistent with previous studies, while NGC 1365 and NGC 1433 exhibit weaker correlations. These differences are likely due to the smaller number of identified star-forming regions in these galaxies compared to NGC 1566, as well as the central molecular gas concentrations and varying star formation activity in their bars and nuclear regions. These results also support the idea that the rK-S relation deviates from linearity in extreme environments, such as starburst galaxies and galactic centres. Additionally, we find a generally low median star formation efficiency (SFE) within the bars of these galaxies, suggesting that while bars may drive nuclear starbursts and contribute to bulge growth, they do not significantly increase SFE. Furthermore, a negative correlation between SFE and ΣH2 is observed across the sample, both within and outside the bar regions, suggesting that higher ΣH2 may lead to lower SFE in the central regions of these galaxies. Our findings highlight that ΣH2 plays a primary role in shaping the observed trends in SFE, rather than the presence of a bar itself.

Information

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Astronomical Society of Australia