Early flash-ionization lines in SN 2024ggi revealed by high-resolution spectroscopy

• DOI: 10.48550/arxiv.2405.02274
• Publication Date: 2024-05-03
• Authors: Thallis Pessi; R. Cartier; Emilio D. Hueichapan; Danielle de Brito...; J. L. Prieto; Ricardo R. Muñoz; G. E. Medina; P.F. Gonzáles Díaz
• Keywords: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics - Solar and Stellar Astrophysics; 0103 physical sciences; FOS: Physical sciences; Astrophysics - High Energy Astrophysical Phenomena; 01 natural sciences; Solar and Stellar Astrophysics (astro-ph.SR)

We present an analysis of very early high-resolution spectroscopic observations the nearby core-collapse (CC) supernova (SN) 2024ggi, a Type II SN that ocurred in galaxy NGC 3621, at distance 7.11 Mpc ($z\approx0.002435$). These represent earliest spectroscopy CCSN ever made. analyze early-phase evolution 2024ggi obtained short interval 26.6 and 33.8h after first light. Observations were with spectrograph MIKE ($R\approx22600-28000$) 6.5m Magellan Clay Telescope, located Las Campanas Observatory, during night 2024-04-12UT. constrain emission line features 2024ggi. main occurrence high-ionization lines, by estimating their full width half maximum (FWHM), equivalent (EW), blueshift velocities. then compare our results to other early-time CCSNe. The spectra show strong narrow Balmer lines species HeI, HeII, NIII, CIII, together relatively broader NIV CIV. Some these become or disappear 8h, indicating rapid changes CCSNe flash-ionization features. CIV, have asymmetric Lorentzian profiles, HeII $\lambda4686$ broad component showing blue wings extends up $\sim-1000$ km s$^{-1}$. also measure CSM expansion velocity $\sim 79 \ \textrm{km} \textrm{s}^{-1}$ from H$\alpha$ profile, total extinction sight $E(B-V)=0.16$ mag. Finally, we note many similarities 2023ixf.