SN 2017egm: A Helium-rich Superluminous Supernova with Multiple Bumps in the Light Curves

  • Zhu J
  • Jiang N
  • Dong S
  • et al.
6Citations
Citations of this article
5Readers
Mendeley users who have this article in their library.

Abstract

When discovered, SN 2017egm was the closest (redshift z = 0.03) hydrogen-poor superluminous supernova (SLSN-I) and a rare case that exploded in a massive and metal-rich galaxy. Thus, it has since been extensively observed and studied. We report spectroscopic data showing strong emission at around He i λ 10830 and four He i absorption lines in the optical. Consequently, we classify SN 2017egm as a member of an emerging population of helium-rich SLSNe-I (i.e., SLSNe-Ib). We also present our late-time photometric observations. By combining them with archival data, we analyze high-cadence ultraviolet, optical, and near-infrared light curves spanning from early pre-peak (∼−20 days) to late phases (∼+300 days). We obtain its most complete bolometric light curve, in which multiple bumps are identified. None of the previously proposed models can satisfactorily explain all main light-curve features, while multiple interactions between the ejecta and circumstellar material (CSM) may explain the undulating features. The prominent infrared excess with a blackbody luminosity of 10 7 –10 8 L ⊙ detected in SN 2017egm could originate from the emission of either an echo of a pre-existing dust shell or newly formed dust, offering an additional piece of evidence supporting the ejecta–CSM interaction model. Moreover, our analysis of deep Chandra observations yields the tightest-ever constraint on the X-ray emission of an SLSN-I, amounting to an X-ray-to-optical luminosity ratio ≲10 −3 at late phases (∼100–200 days), which could help explore its close environment and central engine.

Cite

CITATION STYLE

APA

Zhu, J., Jiang, N., Dong, S., Filippenko, A. V., Rudy, R. J., Pastorello, A., … Zheng, W. (2023). SN 2017egm: A Helium-rich Superluminous Supernova with Multiple Bumps in the Light Curves. The Astrophysical Journal, 949(1), 23. https://doi.org/10.3847/1538-4357/acc2c3

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free