The Mystery of Photometric Twins DES17X1boj and DES16E2bjy

M. Pursiainen , C.P. Gutiérrez , P. Wiseman , M. Childress , M. Smith , C. Frohmaier , C. Angus , N. Castro Segura , L. Kelsey , M. Sullivan , L. Galbany , P. Nugent , B.A. Bassett , D. Brout , D. Carollo , C.B. d'Andrea , T.M. Davis , R.J. Foley , M. Grayling , S.R. Hinton , C. Inserra , R. Kessler , C. Lidman , E. Macaulay , M. March , A. Möller (1) , T. Müller , D. Scolnic , N.E. Sommer , E. Swann , B.P. Thomas , B.E. Tucker , M. Vincenzi , T.M.C. Abbott , S. Allam , J. Annis , S. Avila , E. Bertin (2) , D. Brooks , E. Buckley-Geer , D.L. Burke , A. Carnero Rosell , M. Carrasco Kind , L.N. da Costa , J. de Vicente , S. Desai , H.T. Diehl , P. Doel , T.F. Eifler , S. Everett , B. Flaugher , J. Frieman , J. García-Bellido , E. Gaztanaga , D.W. Gerdes , D. Gruen , R.A. Gruendl , J. Gschwend , G. Gutierrez , D.L. Hollowood , K. Honscheid , D.J. James , A.G. Kim , E. Krause , K. Kuehn , G.F. Lewis , M.A.G. Maia , J.L. Marshall , F. Menanteau , R. Miquel , R.L.C. Ogando , A. Palmese , F. Paz-Chinchón , A.A. Plazas , A. Roodman , E. Sanchez , V. Scarpine , M. Schubnell , S. Serrano , I. Sevilla-Noarbe , E. Suchyta , M.E.C. Swanson , G. Tarle , W. Wester

1 LPC - Laboratoire de Physique de Clermont
2 IAP - Institut d'Astrophysique de Paris

We present an analysis of DES17X1boj and DES16E2bjy, two peculiar transients discovered by the Dark Energy Survey (DES). They exhibit nearly identical double-peaked light curves that reach very different maximum luminosities (M_r = −15.4 and −17.9, respectively). The light-curve evolution of these events is highly atypical and has not been reported before. The transients are found in different host environments: DES17X1boj was found near the nucleus of a spiral galaxy, while DES16E2bjy is located in the outskirts of a passive red galaxy. Early photometric data are well fitted with a blackbody and the resulting moderate photospheric expansion velocities (1800  km s^−1 for DES17X1boj and 4800  km s^−1 for DES16E2bjy) suggest an explosive or eruptive origin. Additionally, a feature identified as high-velocity Ca ii absorption (⁠|$v$| ≈ 9400 km s^−1) in the near-peak spectrum of DES17X1boj may imply that it is a supernova. While similar light-curve evolution suggests a similar physical origin for these two transients, we are not able to identify or characterize the progenitors.

Mots clés: supernovae: general

Domaines: Astrophysique [astro-ph]

M. Pursiainen, C.P. Gutiérrez, P. Wiseman, M. Childress, M. Smith, et al.. The Mystery of Photometric Twins DES17X1boj and DES16E2bjy. Mon.Not.Roy.Astron.Soc., 2020, 494 (4), pp.5576-5589. ⟨10.1093/mnras/staa995⟩. ⟨hal-02403592⟩