SN 2022xlp: The second-known well-observed, intermediate-luminosity Iax supernova

TL;DR

This study analyzes SN 2022xlp, a well-observed intermediate-luminosity Type Iax supernova, to test whether physical properties vary continuously across the Iax luminosity range. The authors combine multicolor photometry, UV data, spectroscopy, Arnett diffusion-model fitting, and spectral tomography using the TARDIS radiative transfer code to derive ejecta properties and compare them with pure deflagration simulations. They find M_56Ni ≈ 0.019–0.021 M⊙, M_ej ≈ 0.14–0.18 M⊙, and E_kin ≈ (0.8–2)×10^49 erg, with rapid early color evolution and later convergence toward iron-dominated spectra; the outer ejecta show enhanced Na. The results, including a density cutoff at v_lim ≈ 4400 km s−1 and Na enrichment, support a continuous Iax family shaped by pure deflagration physics and bridge SN 2019muj with other Iax events, providing evidence for a unified framework across the subclass.

Abstract

We present a detailed analysis of type Iax supernova SN 2022xlp. With a V-band absolute magnitude light curve peaking at $M_{max}(V) = -16.04 \pm 0.25$ mag, this object is regarded as the second determined well-observed Iax supernova in the intermediate luminosity range after SN 2019muj. Our research aims to explore the question of whether the physical properties vary continuously across the entire luminosity range. We also investigate the chemical abundance profiles and the characteristic physical quantities of the ejecta, followed by tests of the predictions of hydro simulations. The pseudo-bolometric light curve was calculated using optical and UV (Swift UVOT ) light curves and fits with a radiation diffusion Arnett model to constrain the average optical opacity, ejected mass, and initial nickel mass produced in the explosion. We analyzed the color evolution of SN 2022xlp and compared it with that of other Iax supernovae with different peak luminosities. We used the spectral tomography method to determine the radial profiles of physical properties and abundances of the ejecta, comparing them with a set of hydrodynamic pure deflagration models. The estimated bolometric flux peaks at $8.87\times 10^{41}$ erg/s and indicates the production of radioactive nickel as $M(^{56}$Ni) = $0.0215 \pm 0.009\,M_{\odot}$. According to the best-fit model, the explosion energy is $(2.066 \pm 0.236) \times 10^{49}$ erg and the ejecta mass is $0.142 \pm 0.015\,M_{\odot}$. The performed spectral tomography analysis shows that the determined physical quantities agree well with the predictions of the deflagration simulations, with modifications regarding the increased Na abundance and the more massive outer layers. SN 2022xlp bridges the previously existing luminosity gap, and supports the assumption of continuous variation in the physical properties across the SN Iax subclass.

Figures (12)

• Figure 1: Image of NGC 3938 hosted the SN 2022xlp. This picture was taken with the BRC80 telescope in the Baja Astronomical Observatory of the University of Szeged.
• Figure 2: Ground-based photomety of SN 2022xlp. The zoom-inset highlights the near-maximum observations. Data measured by the BRC80 telescope are marked with triangles, while filled circles mark the LCO data points.
• Figure 3: Optical spectra of SN 2022xlp. The characteristic spectral features are highlighted by gray stripes. The phase relative to the V-band maximum ($t_\textrm{V}$) and the time since the explosion ($t_\textrm{exp}$) are also marked.
• Figure 4: Pseudo-bolometric LC of SN 2022xlp and the best-fit synthetic light model.
• Figure 5: Evolution of different color indexes compared to another SNe Iax (SN 2019muj - SN2019muj, SN 2012Z - SN2012Z, and SN 2008ha - SN2008ha;SN2008ha-SN2010ae-2). SN 2022xlp shows a very similar color evolution to SN 2019muj. The color indexes are corrected for the extinction as described in Sect. \ref{['section:photmetry-photometric-analysis']}. We adopted the color excess from the papers listed above.