Probing the Nature of the Circumstellar Material Surrounding SN 2024ggi: A Search for Precursor Emission and Constraints from Radio Observations
We present an analysis of the pre-explosion optical light curve and post-explosion radio observations of the nearby supernova (SN) 2024ggi, a Type II SN discovered in NGC 3621 at a distance of ~7.2 Mpc. Early spectra confirmed that SN 2024ggi showed ``IIn-like'' features, suggesting the presence of dense circumstellar material (CSM). We searched for precursor emission in the light curve up to 8 years pre-explosion from ATLAS using ATClean, which cleaned the light curve and effectively convolved it with rolling Gaussians of several timescales. No significant evidence for precursor variability was found. We find 80% detection thresholds on the absolute magnitude of -11.28 mag and -8.98 mag for outbursts with timescales of 2 and 300 days, respectively. Our radio observations taken with the Australia Telescope Compact Array (ATCA) are consistent with a wind-like CSM density profile, with an inferred mass-loss rate of ${\sim} 8 \times 10^{-5} M_\odot$ yr$^{-1}$, assuming $v_{\rm wind} = 50$ km s$^{-1}$. However, including CSM density estimates from the literature implies a two-component structure in the overall CSM density profile, with a denser inner structure at smaller radii ($\lesssim 6\times10^{14}$ cm) and an extended wind-like profile at larger radii. We conclude that the dense CSM around SN 2024ggi is likely not deposited there by eruptive outbursts. Instead, we favor a scenario with a lower but more stable mass-loss rate, such as pulsation-driven superwinds, a model with extended chromospheres, or a combination of both.