title: A possible macronova in the late afterglow of the long-short burst GRB 060614.
abstract: Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova--the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole-neutron star merger but a double neutron star merger cannot be ruled out.
authors.affiliation: 1] Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China [2] University of Chinese Academy of Sciences, Yuquan Road 19, Beijing 100049, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Jin
authors.affiliation: 1] Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China [2] University of Chinese Academy of Sciences, Yuquan Road 19, Beijing 100049, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807 Merate, Italy.
authors.forename: Stefano
authors.identifier: 0000000190785507
authors.initials: S
authors.lastname: Covino
authors.affiliation: Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Xian-Zhong
authors.initials: XZ
authors.lastname: Zheng
authors.affiliation: Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: Kenta
authors.initials: K
authors.lastname: Hotokezaka
authors.affiliation: 1] Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China [2] Collaborative Innovation Center of Modern Astronomy and Space Exploration, Nanjing University, Nanjing 210046, China.
authors.forename: Yi-Zhong
authors.initials: YZ
authors.lastname: Fan
authors.affiliation: Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: Tsvi
authors.initials: T
authors.lastname: Piran
authors.affiliation: Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Wei