Searching for Magnetar-powered Merger-novae from Short GRBS

Abstract

The merger of a double neutron star (NS-NS) binary may result in a rapidly rotating massive NS with an extremely strong magnetic field (i.e., a millisecond magnetar). In this case, the magnetic spin-down of the NS remnant provides an additional source of sustained energy injection, which would continuously power the merger ejecta. The thermal emission from the merger ejecta would give rise to a bright optical "magnetarpowered merger-nova". In this work, we carry out a complete search for magnetar-powered merger-nova from Swift short gamma-ray burst (SGRB) sample. We focus on short GRBs with extended emission or internal plateau, which may signify the presence of magnetars as the central engine. We eventually find three candidates of magnetar-powered merger-nova from the late observations of GRB 050724, GRB 070714B and GRB 061006. With standard parameter values, the magnetar remnant scenario could well interpret the multi-band data of all three bursts, including the extended emission and their late chromatic features in the optical and X-ray data. The peak luminosities of these merger-novae reach several times 10 42 erg s −1 , more than one order of magnitude brighter than the traditional "kilo-novae" with peak luminosity of ∼ 10 41 erg s −1 . Intense, multi-color late time observations of short GRBs are encouraged to identify more merger-novae in the future.

Possible correlations between gamma-ray burst and its host galaxy offset

“…A possible explanation might be that at the birth of the NS or BH, for very high speed NS, the companion compact star has the chance to decouple, while the high speed BH (with more mass) binary can survive, and consequently reaches to outer area of the host galaxy. Also because of the range of the BH masses, it may explain the variety of the magnitude of the kilonovae (or called macronovae, merger novae) (Gao et al, 2017). We have analyzed the correlations by dividing the sample into long GRBs and short GRBs based on the duration being greater or smaller than 2s.…”

Gamma-ray bursts associating with gravitational waves from compact binary mergers

“…2013年, 哈 勃 望 远 镜 在 短 伽 马 暴GRB 130603B发生约一周后观测到了一个明亮的近红 外辐射, 其流量明显超出了该暴近红外余辉辐射 的理论预期 [89] , 从而被认为是第一例千新星候选 体. 受此启发, 人们对2013年之前观测到的短伽马 暴余辉进行了仔细的检查, 从中又发现了多例疑 似的候选体 [90][91][92] . 此后, 在新的短伽马暴(如GRB 140903A和GRB 160821B)观测中, 类似的候选体仍 然在不断地被发现 [93,94] .…”

r-process nucleosynthesis in a double neutron-star merger: the case of GW170817

“…The luminosity, color and timescale of this possible component were consistent with the predictions from kilonova models (see [10] and reference therein). Other, possible cases of kilonova signatures were found in the afterglows of the short GRB 050709 and the peculiar long GRB 060614 [11], the short GRB 080503 ( [12]; [13]), 160821B ( [14]; [15]) and 150101B [16].…”