Issue |
A&A
Volume 673, May 2023
|
|
---|---|---|
Article Number | A107 | |
Number of page(s) | 26 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202245406 | |
Published online | 17 May 2023 |
Toward nebular spectral modeling of magnetar-powered supernovae
The Oskar Klein Centre, Department of Astronomy, Stockholm University, Albanova
10691,
Stockholm,
Sweden
e-mail: conor.omand@astro.su.se
Received:
8
November
2022
Accepted:
13
March
2023
Context. Many energetic supernovae (SNe) are thought to be powered by the rotational energy of a highly magnetized, rapidly rotating neutron star. The emission from the associated luminous pulsar wind nebula (PWN) can photoionize the SN ejecta, leading to a nebular spectrum of the ejecta with signatures that might reveal the PWN. SN 2012au is hypothesized to be one such SN.
Aims. We investigate the impact of different ejecta and PWN parameters on the SN nebular spectrum, and test whether any photoionization models are consistent with SN 2012au. We study how constraints from the nebular phase can be linked into modeling of the diffusion phase and the radio emission of the magnetar.
Methods. We present a suite of late-time (1–6 yr) spectral simulations of SN ejecta powered by an inner PWN. Over a large grid of one-zone models, we study the behavior of the physical state and line emission of the SN as the PWN luminosity (LPWN), the injected spectral energy distribution (SED) temperature (TPWN), the ejecta mass (Mej), and the composition (pure O or realistic) vary. We discuss the resulting emission in the context of the observed behavior of SN 2012au, a strong candidate for a PWN-powered SN. We used optical light-curve models and broadband PWN models to predict possible radio emission from SN 2012au.
Results. The SN nebular spectrum varies as TPWN varies because the ejecta become less ionized as TPWN increases. Ejecta models with low mass and high PWN power obtain runaway ionization for O I, and in extreme cases, also O II, causing a sharp decrease in their ion fraction over a small change in the parameter space. Certain models can reproduce the oxygen line luminosities of SN 2012au reasonably well at individual epochs, but we find no model that fits over the whole time evolution. This is likely due to uncertainties and simplifications in the model setup. Using our derived constraints from the nebular phase, we predict that the magnetar powering SN 2012au had an initial rotation period ~15 ms, and it is expected to be a strong radio source (F > 100 μJy) for decades.
Key words: radiative transfer / stars: magnetars / supernovae: general / supernovae: individual: SN 2012au
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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