SN 2015bn: A DETAILED MULTI-WAVELENGTH VIEW OF A NEARBY SUPERLUMINOUS SUPERNOVA

Abstract

We present observations of SN 2015bn (= PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at redshift z = 0.1136. As well as being one of the closest SLSNe I yet discovered, it is intrinsically brighter (M U ≈ −23.1) and in a fainter galaxy (M B ≈ −16.0) than other SLSNe at z ∼ 0.1. We used this opportunity to collect the most extensive dataset for any SLSN I to date, including densely-sampled spectroscopy and photometry, from the UV to the NIR, spanning −50 to +250 days from optical maximum. SN 2015bn fades slowly, but exhibits surprising undulations in the light curve on a timescale of 30-50 days, especially in the UV. The spectrum shows extraordinarily slow evolution except for a rapid transformation between +7 and +20-30 days. No narrow emission lines from slow-moving material are observed at any phase. We derive physical properties including the bolometric luminosity, and find slow velocity evolution and non-monotonic temperature and radial evolution. A deep radio limit rules out a healthy off-axis gamma-ray burst, and places constraints on the pre-explosion mass loss. The data can be consistently explained by a 10 M stripped progenitor exploding with ∼ 10 51 erg kinetic energy, forming a magnetar with arXiv:1603.04748v3 [astro-ph.SR] 22 Jul 2016 a spin-down timescale of ∼ 20 d (thus avoiding a gamma-ray burst) that reheats the ejecta and drives ionization fronts. The most likely alternative scenario -interaction with ∼ 20 M of dense, inhomogeneous circumstellar material -can be tested with continuing radio follow-up.

Euclid: Superluminous supernovae in the Deep Survey

“…This has been built fitting literature data (e.g. Inserra et al 2013;Nicholl et al 2015) with low-order polynomials (as done in Nicholl et al 2016) and the magnetar model (Inserra et al 2013), allowing a reduced χ Lunnan et al (2017). We utilized an empirical template for the spectral energy distribution (SED) of SLSN-I based on 110 rest-frame spectra taken for 20 SLSNe-I spanning a redshift range of 0.1 < z < 1.…”

“…Observed phase is with respect to the observer frame J-band peak. Inserra et al 2013;Nicholl et al 2013Nicholl et al , 2014Vreeswijk et al 2014;Nicholl et al 2016). …”

The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system

“…4, we examine the evolution of the lines and continuum in more detail using spectral synthesis models (Mazzali et al 2016). (2013); Nicholl et al (2013Nicholl et al ( , 2015bNicholl et al ( , 2016b; Vreeswijk et al (2014).…”

Properties of Magnetars Mimicking 56Ni-Powered Light Curves in Type IC Superluminous Supernovae

“…However, subsequent theoretical and observational studies suggest that the short LC rise times and little line blanketing of slowly-declining Type Ic SLSNe like SN 2007bi are inconsistent with 56 Ni-powered PISNe and prefer the magnetar-powered model (e.g., Dessart et al 2012;Inserra et al 2013;Nicholl et al 2013Nicholl et al , 2015bNicholl et al , 2016aMcCrum et al 2014;Chen et al 2015;Jerkstrand et al 2016a,b;Mazzali et al 2016) or other power sources (e.g., Chevalier & Irwin 2011;Ginzburg & Balberg 2012;Moriya & Maeda 2012;Ouyed et al 2012;Chatzopoulos et al 2013b;Dexter & Kasen 2013;Baklanov et al 2015;Sorokina et al 2016;Nicholl et al 2015a;Wang et al 2016). In addition, there also exist many Type Ic SLSNe with fast LC declines that cannot be explained by the 56 Ni power (e.g., Pastorello et al 2010;Chomiuk et al 2011;Inserra et al 2013;Howell et al 2013;Nicholl et al 2015b).…”

“…One interesting feature of slowly-declining Type Ic SLSNe is that their LC decline rates are often consistent with the 56 Co decay rate for a long time (e.g., Nicholl et al 2016a;Chen et al 2015;Papadopoulos et al 2015;Yan et al 2015;Lunnan et al 2016;Vreeswijk et al 2016). If we just examine the late-phase LCs, the simplest way to explain them is the 56 Co decay.…”