NO PRECISE LOCALIZATION FOR FRB 150418: CLAIMED RADIO TRANSIENT IS AGN VARIABILITY
NO PRECISE LOCALIZATION FOR FRB 150418: CLAIMED RADIO TRANSIENT IS AGN VARIABILITY
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DOI：
10.3847/2041-8205/821/2/l22
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发表时间：
2016-02
期刊：
影响因子：
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通讯作者：
P. G. Williams;E. Berger
中科院分区：
文献类型：
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作者：
P. G. Williams;E. Berger
Keane等人最近声称，由于确定了同期衰落缓慢（约一周时间尺度）的无线电瞬变，他们首次获得了快速无线电暴（FRB）的精确定位。他们利用这一定位将快速射电暴定位到z≈0.49的星系，该星系没有明显的恒星形成活动。我们认为，这一瞬态现象不是真实的，主候选天体WISE J071634.59−190039.2是一个射电变量：现有数据不排除这种可能性；与观测一致的随机无线电变量并非不可能具有与快速射电暴色散测量相容的红移；所提出的瞬态光曲线最好解释为闪烁的稳定源，可能也显示了活动的星系核（AGN）耀斑，而不是同步辐射的冲击波。候选宿主的射电亮度表明它是一个AGN，我们提出了新的后期甚大阵列观测结果，表明该星系确实在与所声称的瞬态一致的水平上变化。因此，声称FRB 150418的精确定位和红移测定是不合理的。
Keane et al. have recently claimed to have obtained the first precise localization for a fast radio burst (FRB) thanks to the identification of a contemporaneous fading slow (∼week-timescale) radio transient. They use this localization to pinpoint the FRB to a galaxy at z ≈ 0.49 that exhibits no discernible star formation activity. We argue that the transient is not genuine and that the host candidate, WISE J071634.59−190039.2, is instead a radio variable: the available data did not exclude this possibility; a random radio variable consistent with the observations is not unlikely to have a redshift compatible with the FRB dispersion measure; and the proposed transient light curve is better explained as a scintillating steady source, perhaps also showing an active galactic nucleus (AGN) flare, than a synchrotron-emitting blastwave. The radio luminosity of the host candidate implies that it is an AGN and we present new late-time Very Large Array observations showing that the galaxy is indeed variable at a level consistent with the claimed transient. Therefore the claimed precise localization and redshift determination for FRB 150418 cannot be justified.