Stellar Feedback in the Star Formation-Gas Density Relation: Comparison between Simulations and Observations

Abstract: Context. The impact of stellar feedback on the Kennicutt-Schmidt law (KS law), which relates star formation rate (SFR) to surface gas density, is a topic of ongoing debate. The interpretation of individual cloud observations is challenging due to the various processes at play simultaneously and inherent biases. Therefore, a numerical investigation is necessary to understand the role of stellar feedback and identify observable signatures. Aims. We investigate the role of stellar feedback on the KS law, aiming to identify distinct signatures that can be observed and analysed. Methods. We analyse MHD numerical simulations of a $10<sup>4\,M_{\odot}$ cloud evolving under different feedback prescriptions. The set of simulations contains four types of feedback: with only protostellar jets, with ionising radiation from massive stars $(&gt;8\,M_{\odot})$, with both of them and without any stellar feedback. To compare these simulations with the existing observational results, we analyse their evolution by adopting the same techniques applied in observational studies. Then, we simulate how the same analyses would change if the data were affected by typical observational biases. Conclusions. The presence of stellar feedback strongly influences the KS relation and the star formation efficiency per free-fall time ($\epsilon_\mathrm{ff}$). Its impact is primarily governed by its influence on the cloud's structure. Although the $\epsilon_\mathrm{ff}$ measured in our clouds results to be higher than what is usually observed in real clouds, upon applying prescriptions to mimic observational biases we recover good agreement with the expected values. Therefore, we can infer that observations tend to underestimate the total SFR. Moreover, this likely indicates that the physics included in our simulations is sufficient to reproduce the basic mechanisms contributing to set $\epsilon_\mathrm{ff}$.