Where is the engine hiding its missing energy? Constraints from a deep X-ray non-detection of the Superluminous SN 2015bn

Abstract

SN 2015bn is a nearby hydrogen-poor superluminous supernova (SLSN-I) that has been intensively observed in X-rays with the goal to detect the spin-down powered emission from a magnetar engine. The early-time UV/optical/infrared (UVOIR) data fit well to the magnetar model, but require leakage of energy at late times of $\lesssim 10^{43}$ erg s${}^{-1}$, which is expected to be partially emitted in X-rays. Deep X-ray limits until $\sim$300 days after explosion revealed no X-ray emission. Here, we present the latest deep 0.3--10 keV X-ray limit at 805 days obtained with \textit{XMM-Newton}. We find $L_X<10^{41}$ erg s${}^{-1}$, with no direct evidence for central-engine powered emission. While the late-time optical data still follow the prediction of the magnetar model, the best-fit model to the bolometric light curve predicts that $\sim$97\% of the total input luminosity of the magnetar is escaping outside of the UVOIR bandpass at the time of observation. Our X-ray upper limit is $<$1.5\% of the input luminosity, strongly constraining the high-energy leakage, unless non-radiative losses are important. These deep X-ray observations identify a missing energy problem in SLSNe-I and we suggest future observations in hard X-rays and $\gamma$-rays for better constraints. Also, independent of the optical data, we constrain the parameter spaces of various X-ray emission scenarios, including ionization breakout by magnetar spin-down, shock interaction between the ejecta and external circumstellar medium, off-axis $\gamma$-ray burst afterglow, and black hole fallback accretion.

9 pages, 4 figures, 1 table, submitted to AAS Journals

References in corpus (18)

• Circumstellar Emission from Type Ib and Ic Supernovae
• The magnetar model for Type I superluminous supernovae I: Bayesian analysis of the full multicolour light curve sample with MOSFiT
• MOSFiT: Modular Open-Source Fitter for Transients
• The First Swift Ultra-Violet/Optical Telescope GRB Afterglow Catalog
• Effects of Fall-Back Accretion on Proto-Magnetar Outflows in Gamma-Ray Bursts and Superluminous Supernovae
• Superluminous supernova 2015bn in the nebular phase: evidence for the engine-powered explosion of a stripped massive star
• Superluminous Supernovae Powered by Magnetars: Late-time Light Curves and Hard Emission Leakage
• Unveiling the Engines of Fast Radio Bursts, Super-Luminous Supernovae, and Gamma-Ray Bursts
• Spectropolarimetry of superluminous supernovae: insight into their geometry
• SN 2017ens: The Metamorphosis of a Luminous Broad-lined Type Ic Supernova into an SN IIn
• Stripped-envelope supernova SN 2004dk is now interacting with hydrogen-rich circumstellar material
• SN 2017dio: a type-Ic supernova exploding in a hydrogen-rich circumstellar medium
• Systematic investigation of the fallback accretion powered model for hydrogen-poor superluminous supernovae
• Evidence for a pulsar wind nebula in the Type Ib-peculiar supernova SN 2012au
• One thousand days of SN 2015bn: HST imaging shows a light curve flattening consistent with magnetar predictions
• Time-resolved polarimetry of the superluminous SN 2015bn with the Nordic Optical Telescope
• Jets in Hydrogen-poor Super-luminous Supernovae: Constraints from a Comprehensive Analysis of Radio Observations
• A UV Resonance Line Echo from a Shell Around a Hydrogen-Poor Superluminous Supernova

Cited by in corpus (13)

• Observational properties of extreme supernovae
• Science objectives of the Einstein Probe mission
• A Radio Source Coincident with the Superluminous Supernova PTF10hgi: Evidence for a Central Engine and an Analogue of the Repeating FRB121102?
• Gamma-ray Thermalization and Leakage from Millisecond Magnetar Nebulae: Towards a Self-Consistent Model for Superluminous Supernovae
• Superluminous supernovae: an explosive decade
• Multimessenger Implications of AT2018cow: High-Energy Cosmic Ray and Neutrino Emissions from Magnetar-Powered Super-Luminous Transients
• 2D radiation-hydrodynamic simulations of supernova ejecta with a central power source
• Four (Super)luminous Supernovae from the First Months of the ZTF Survey
• ALMA and NOEMA constraints on synchrotron nebular emission from embryonic superluminous supernova remnants and radio-gamma-ray connection
• A Generalized Semi-Analytic Model for Magnetar-Driven Supernovae
• Periodic Fast Radio Bursts from Young Neutron Stars
• VERITAS and Fermi-LAT constraints on the Gamma-ray Emission from Superluminous Supernovae SN2015bn and SN2017egm
• Hard X-ray Observations of the Hydrogen-poor Superluminous Supernova SN 2018hti with NuSTAR