Gaia17biu/SN 2017egm in NGC 3191: The Closest Hydrogen-poor Superluminous Supernova to Date Is in a "Normal," Massive, Metal-rich Spiral Galaxy Academic Article uri icon


  • 2018. The American Astronomical Society. All rights reserved. Hydrogen-poor superluminous supernovae (SLSNe-I) have been predominantly found in low-metallicity, star-forming dwarf galaxies. Here we identify Gaia17biu/SN 2017egm as an SLSN-I occurring in a "normal" spiral galaxy (NGC 3191) in terms of stellar mass (several times 1010 M o) and metallicity (roughly solar). At redshift z = 0.031, Gaia17biu is also the lowest-redshift SLSN-I to date, and the absence of a larger population of SLSNe-I in dwarf galaxies of similar redshift suggests that metallicity is likely less important to the production of SLSNe-I than previously believed. With the smallest distance and highest apparent brightness for an SLSN-I, we are able to study Gaia17biu in unprecedented detail. Its pre-peak near-ultraviolet to optical color is similar to that of Gaia16apd and among the bluest observed for an SLSN-I, while its peak luminosity (M g = -21 mag) is substantially lower than that of Gaia16apd. Thanks to the high signal-to-noise ratios of our spectra, we identify several new spectroscopic features that may help to probe the properties of these enigmatic explosions. We detect polarization at the 0.5% level that is not strongly dependent on wavelength, suggesting a modest, global departure from spherical symmetry. In addition, we put the tightest upper limit yet on the radio luminosity of an SLSN-I with <5.4 1026 erg s-1 Hz-1 at 10.GHz, which is almost a factor of 40 better than previous upper limits and one of the few measured at an early stage in the evolution of an SLSN-I. This limit largely rules out an association of this SLSN-I with known populations of gamma-ray-burst-like central engines.

published proceedings


altmetric score

  • 5.6

author list (cited authors)

  • Bose, S., Dong, S., Pastorello, A., Filippenko, A. V., Kochanek, C. S., Mauerhan, J., ... Yunus, S.

citation count

  • 60

complete list of authors

  • Bose, Subhash||Dong, Subo||Pastorello, A||Filippenko, Alexei V||Kochanek, CS||Mauerhan, Jon||Romero-CaƱizales, C||Brink, Thomas G||Chen, Ping||Prieto, JL||Post, R||Ashall, Christopher||Grupe, Dirk||Tomasella, L||Benetti, Stefano||Shappee, BJ||Stanek, KZ||Cai, Zheng||Falco, E||Lundqvist, Peter||Mattila, Seppo||Mutel, Robert||Ochner, Paolo||Pooley, David||Stritzinger, MD||Villanueva, S||Zheng, WeiKang||Beswick, RJ||Brown, Peter J||Cappellaro, E||Davis, Scott||Fraser, Morgan||Jaeger, Thomas de||Elias-Rosa, N||Gall, C||Gaudi, B Scott||Herczeg, Gregory J||Hestenes, Julia||Holoien, TW-S||Hosseinzadeh, Griffin||Hsiao, EY||Hu, Shaoming||Jaejin, Shin||Jeffers, Ben||Koff, RA||Kumar, Sahana||Kurtenkov, Alexander||Lau, Marie Wingyee||Prentice, Simon||Reynolds, T||Rudy, Richard J||Shahbandeh, Melissa||Somero, Auni||Stassun, Keivan G||Thompson, Todd A||Valenti, Stefano||Woo, Jong-Hak||Yunus, Sameen

publication date

  • January 2018