title: An extremely luminous panchromatic outburst from the nucleus of a distant galaxy.
abstract: Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ∼100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.
authors.affiliation: Department of Physics, University of Warwick, Coventry, UK. a.j.levan@warwick.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Levan
authors.forename: N R
authors.initials: NR
authors.lastname: Tanvir
authors.forename: S B
authors.initials: SB
authors.lastname: Cenko
authors.forename: D A
authors.initials: DA
authors.lastname: Perley
authors.forename: K
authors.initials: K
authors.lastname: Wiersema
authors.forename: J S
authors.initials: JS
authors.lastname: Bloom
authors.forename: A S
authors.initials: AS
authors.lastname: Fruchter
authors.forename: A de Ugarte
authors.initials: Ade U
authors.lastname: Postigo
authors.forename: P T
authors.initials: PT
authors.lastname: O'Brien
authors.forename: N
authors.initials: N
authors.lastname: Butler
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Horst
authors.forename: G
authors.initials: G
authors.lastname: Leloudas
authors.forename: A N
authors.initials: AN
authors.lastname: Morgan
authors.forename: K
authors.initials: K
authors.lastname: Misra
authors.forename: G C
authors.initials: GC
authors.lastname: Bower
authors.forename: J
authors.initials: J
authors.lastname: Farihi
authors.forename: R L
authors.initials: RL
authors.lastname: Tunnicliffe
authors.forename: M
authors.initials: M
authors.lastname: Modjaz
authors.forename: J M
authors.initials: JM
authors.lastname: Silverman
authors.forename: J
authors.initials: J
authors.lastname: Hjorth
authors.forename: C
authors.initials: C
authors.lastname: Thöne
authors.forename: A
authors.initials: A
authors.lastname: Cucchiara
authors.forename: J M Castro
authors.initials: JM
authors.lastname: Cerón
authors.forename: A J
authors.initials: AJ
authors.lastname: Castro-Tirado
authors.forename: J A
authors.initials: JA
authors.lastname: Arnold
authors.forename: M
authors.initials: M
authors.lastname: Bremer
authors.forename: J P
authors.initials: JP
authors.lastname: Brodie
authors.forename: T
authors.initials: T
authors.lastname: Carroll
authors.forename: M C
authors.initials: MC
authors.lastname: Cooper
authors.forename: P A
authors.initials: PA
authors.lastname: Curran
authors.forename: R M
authors.initials: RM
authors.lastname: Cutri
authors.forename: J
authors.initials: J
authors.lastname: Ehle
authors.forename: D
authors.initials: D
authors.lastname: Forbes
authors.forename: J
authors.initials: J
authors.lastname: Fynbo
authors.forename: J
authors.initials: J
authors.lastname: Gorosabel
authors.forename: J
authors.initials: J
authors.lastname: Graham
authors.forename: D I
authors.initials: DI
authors.lastname: Hoffman
authors.forename: S
authors.initials: S
authors.lastname: Guziy
authors.forename: P
authors.initials: P
authors.lastname: Jakobsson
authors.forename: A
authors.initials: A
authors.lastname: Kamble
authors.forename: T
authors.initials: T
authors.lastname: Kerr
authors.forename: M M
authors.initials: MM
authors.lastname: Kasliwal
authors.forename: C
authors.initials: C
authors.lastname: Kouveliotou
authors.forename: D
authors.initials: D
authors.lastname: Kocevski
authors.forename: N M
authors.initials: NM
authors.lastname: Law
authors.forename: P E
authors.initials: PE
authors.lastname: Nugent
authors.forename: E O
authors.initials: EO
authors.lastname: Ofek
authors.forename: D
authors.initials: D
authors.lastname: Poznanski
authors.forename: R M
authors.initials: RM
authors.lastname: Quimby
authors.forename: E
authors.initials: E
authors.lastname: Rol
authors.forename: A J
authors.initials: AJ
authors.lastname: Romanowsky
authors.forename: R
authors.initials: R
authors.lastname: Sánchez-Ramírez
authors.forename: S
authors.initials: S
authors.lastname: Schulze
authors.forename: N
authors.initials: N
authors.lastname: Singh
authors.forename: L
authors.initials: L
authors.lastname: van Spaandonk
authors.forename: R L C
authors.initials: RL
authors.lastname: Starling
authors.forename: R G
authors.initials: RG
authors.lastname: Strom
authors.forename: J C
authors.initials: JC
authors.lastname: Tello
authors.forename: O
authors.initials: O
authors.lastname: Vaduvescu
authors.forename: P J
authors.initials: PJ
authors.lastname: Wheatley
authors.forename: R A M J
authors.initials: RA
authors.lastname: Wijers
authors.forename: J M
authors.initials: JM
authors.lastname: Winters
authors.forename: D
authors.initials: D
authors.lastname: Xu