WFST Supernovae in the First Year: II. SN 2024aedt: Systematical Study of a Transitional Type Ia Supernova

TL;DR

This paper presents detailed photometric and spectroscopic analysis of the transitional Type Ia supernova SN 2024aedt, highlighting its unique properties and exploring explosion scenarios to understand its nature and diversity.

Contribution

It provides the first comprehensive early-time observations and modeling of SN 2024aedt, offering insights into its transitional characteristics and potential explosion mechanisms.

Findings

SN 2024aedt has a peak magnitude of -18.49 mag and a decline rate of 1.53 mag.

Light-curve modeling estimates a $^{56}$Ni mass of 0.414 M$_\\odot$ and ejecta mass of 0.548 M$_\ ext{\odot}$.

Spectral evolution shows diversity in early blue features, becoming more homogeneous later.

Abstract

We present comprehensive photometric and spectroscopic observations of a transitional type Ia SN 2024aedt, discovered by the 2.5-meter Wide Field Survey Telescope (WFST) within one day of the explosion. Its light curve is characterized by a peak absolute magnitude of $M_B = -18.49 \pm 0.03$ mag and a decline rate of $\Delta m_{15}(B) = 1.53 \pm 0.36$ mag, placing the object on the $\Delta m_{15}(B)$--$M_B$ diagram in the transition region between normal and subluminous SNe Ia. Furthermore, the early-color evolution and host galaxy environment of SN 2024aedt underscore its transitional nature, sharing properties with both normal and 91bg-like SNe Ia. Light-curve modeling with MOSFiT yields a synthesized $^{56}\mathrm{Ni}$ mass of $0.414 \pm 0.042\,M_{\odot}$ and a total ejecta mass of $0.548 \pm 0.108\,M_{\odot}$. A comparison with theoretical models suggests that the evolutionary trend can be broadly explained by both delayed-detonation (DDT) and double-detonation (DDet) scenarios while possible early-excess emissions predicted by DDet cannot be identified given the limited detections soon after the SN explosion. Although the overall spectral evolution of SN 2024aedt is similar to that of other transitional SNe Ia, the spectroscopic comparison reveals diversity in the early-phase blue-end features, which becomes more homogeneous at later phases. The result indicates the importance of early-time observations in understanding the origin of SN Ia diversity.