Digitala Astronomdagarna 2021

SN 2018bsz: significant dust formation in a nearby superluminous supernova

22 Oct 2021, 08:55

10m

Zoom

Talk Kilonovae, Supernovae and SNRs

Speaker

Janet Ting-Wan Chen (Stockholm University)

Description

We investigate the thermal emission and extinction from dust associated with a nearby superluminous supernova (SLSN) at $z=0.0267$, SN~2018bsz, in order to determine its nature. We use the 7-channel imager GROND to extensively monitor the photometric evolution of SN~2018bsz. This is the first dataset with daily cadence and simultaneous optical and near-infrared (NIR) coverage for a SLSN. At $+230$ days, the SN is not detected in the optical and shows significant NIR excess, with $r-J>3$ mag and $r-K_{\mathrm{s}}>5$ mag. We use the $\mathit{\text{Spitzer Space Telescope}}$ to detect the SN at late-times between $+384$ and $+535$ days in 3.6 and 4.5 $\mu$m images. In addition, we recover NEOWISE detections at 3.4 and 4.6 $\mu$m for SN~2018bsz between $+68$ and $+423$ days. The time evolution of the IR lightcurve enables us to investigate whether the mid-infrared emission is from newly formed dust inside the SN ejecta or from a pre-existing circumstellar envelope or interstellar material heated by the radiation from the SN. We find the later two scenarios can be ruled out, and a scenario where new dust is forming at epochs $>200$ days can self-consistently reproduce the evolution of the SN flux. We can fit the spectral energy distribution well between $+230$ and $+380$ days with $5\times {10}^{-4}$ $M_{\odot }$ of carbon dust, subsequently a higher dust mass of ${10}^{-2}$ $M_{\odot }$ is required. SN~2018bsz is the first SLSN showing evidence for dust formation within the SN ejecta, and it could potentially provide an analog for dust formation in the early Universe.

Presentation materials

TWChen_SN2018bsz_Astronomdagarna_20211022.pdf