J W Zhou, A A Han
ABSTRACT We identify voids in NGC 628 from the JWST MIRI F770W image using a deep-learning method (BlendMask) and refine them by intensity contrast. These voids may be feedback-driven bubbles or dynamically formed structures. Cross-matching with archival catalogues of star clusters and associations shows that only up to 17.6 per cent of voids are associated with such stellar populations. The HST B-band peak-flux distributions of voids with and without these populations overlap substantially, suggesting that many related clusters/associations remain unidentified or misclassified in current catalogues. Voids associated with star clusters or associations tend to have lower intensity contrast and larger sizes. An anticorrelation between void size and intensity contrast indicates that larger voids have emptier centres, possibly due to more substantial feedback. Hence, voids may provide a complementary tracer for identifying stellar populations and constraining their physical properties. To quantify spatial relationships among CO, 21 µm, H$_{\alpha }$ sources, and voids, we construct networks linking each source pair. Among the nine networks, 21 µm and H$_{\alpha }$ sources show the strongest spatial association. Compared to small voids, large voids exhibit progressively increasing separations from CO to 21 µm, then to H$_{\alpha }$ sources, and finally to the voids, consistent with an evolutionary sequence in space and time. Smaller voids lie closer to molecular clouds, while larger voids are more displaced. Compared with molecular clouds not associated with voids, those associated with voids are significantly more massive and appear to be more evolved. In fact, 68 per cent of molecular clouds associated with voids are also associated with 21 µm sources. These results support an evolutionary scenario in which some voids originate within molecular clouds, grow through stellar feedback, and gradually detach from their parent clouds.