Extended Shock Breakout and Early Circumstellar Interaction in SN 2024ggi

September 2024 • 2024ApJ...972L..15S

Authors • Shrestha, Manisha • Bostroem, K. Azalee • Sand, David J. • Hosseinzadeh, Griffin • Andrews, Jennifer E. • Dong, Yize • Hoang, Emily • Janzen, Daryl • Pearson, Jeniveve • Jencson, Jacob E. • Lundquist, M. J. • Mehta, Darshana • Ravi, Aravind P. • Meza Retamal, Nicolás • Valenti, Stefano • Brown, Peter J. • Jha, Saurabh W. • Macrie, Colin • Hsu, Brian • Farah, Joseph • Howell, D. Andrew • McCully, Curtis • Newsome, Megan • Padilla Gonzalez, Estefania • Pellegrino, Craig • Terreran, Giacomo • Kwok, Lindsey • Smith, Nathan • Schwab, Michaela • Martas, Aidan • Munoz, Ricardo R. • Medina, Gustavo E. • Li, Ting S. • Diaz, Paula • Hiramatsu, Daichi • Tucker, Brad E. • Wheeler, J. C. • Wang, Xiaofeng • Zhai, Qian • Zhang, Jujia • Gangopadhyay, Anjasha • Yang, Yi • Gutiérrez, Claudia P.

Abstract • We present high-cadence photometric and spectroscopic observations of supernova (SN) 2024ggi, a Type II SN with flash spectroscopy features, which exploded in the nearby galaxy NGC 3621 at ∼7 Mpc. The light-curve evolution over the first 30 hr can be fit by two power-law indices with a break after 22 hr, rising from M _V ≈ ‑12.95 mag at +0.66 day to M _V ≈ ‑17.91 mag after 7 days. In addition, the densely sampled color curve shows a strong blueward evolution over the first few days and then behaves as a normal SN II with a redward evolution as the ejecta cool. Such deviations could be due to interaction with circumstellar material (CSM). Early high- and low-resolution spectra clearly show high-ionization flash features from the first spectrum to +3.42 days after the explosion. From the high-resolution spectra, we calculate the CSM velocity to be 37 ± 4 km s^‑1. We also see the line strength evolve rapidly from 1.22 to 1.49 days in the earliest high-resolution spectra. Comparison of the low-resolution spectra with CMFGEN models suggests that the pre-explosion mass-loss rate of SN 2024ggi falls in the range of 10^‑3–10^‑2 M _☉ yr^‑1, which is similar to that derived for SN 2023ixf. However, the rapid temporal evolution of the narrow lines in the spectra of SN 2024ggi (R _CSM ∼ 2.7 × 10¹⁴ cm) could indicate a smaller spatial extent of the CSM than in SN 2023ixf (R _CSM ∼ 5.4 × 10¹⁴ cm), which in turn implies a lower total CSM mass for SN 2024ggi.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2024ApJ...972L..15S
• PREPRINT http://arxiv.org/abs/2405.18490
• DATA https://archive.gemini.edu/searchform/publication=2024ApJ...972L..15S
• ELECTR https://doi.org/10.3847%2F2041-8213%2Fad6907