论文标题
考拉：一个快速的蓝色光学瞬变，带有$ z = 0.27 $的星爆矮星银河的发光无线电发射
The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at $z=0.27$
论文作者
论文摘要
我们提出了ZTF18ABVKWLA（“ Koala”），这是一种在Zwicky Transient设施（ZTF）一日节奏（1DC）调查中发现的快速蓝光瞬变。 ZTF18ABVKWLA具有许多特征与开创性的短暂性AT2018COW：峰值（$ g-r \ r \ \ r \ 0.5 $ mag）的蓝色，从两天不到两天的半程衰减时间，衰减时间的半个衰减时间到半个半麦克斯的短时间，仅三天，三天，高光度杂志（$ m_ peep）（$ m_ peep）（$ m_ {$ \ feep）。 （$ \ gtrsim 40,000 $ k）在峰值灯光下的无特色频谱和发光的广播对应物。在后期（$ΔT> 80 $ d）ZTF18ABVKWLA的无线电发光度（$νl_ν\ gtrsim 10^{40} $ erg/s在10 GHz，观察者框架，观察者框架）最相似，与长期伽马射线脉冲（GRBS）最相似。主机星系是一个矮人的星球星系（$ m \ of times10^{8} m_ \ odot $，$ \ mathrm {sfr} \ of7 m_ \ odot $/yr），是中等金属的enriched（$ \ log \ log \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ mathrm {ostrys）超小型超新星。与AT2018COW一样，ZTF18ABVKWLA中的无线电和光学排放可能来自两个单独的组件：来自快速移动的弹射器（$γβC> 0.38C $）的无线电以及与密集的密集材料（$ <0.07m_ \ odot $ in $ <0.07m_ \ odot $ in $ \ sim \ sim sim sim sim 10^15^15} $ c的震动相互交流。用$ t_ \ mathrm {rise} <5 $ d和$ m_ \ mathrm {peak} <-20 $ mag编译文献中的瞬变，我们发现大量数量是发动机驱动的，并建议高峰光学光度直接相关。从1DC调查的18个月开始，我们发现在这种上升 - 露光度相空间中的瞬态至少比CC SNE少2到三个数量级。最后，我们讨论了与未来的设施（如大型Symoptic调查望远镜）一起识别此类事件的策略，以及检测X射线和无线电排放的前景。
We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT2018cow: blue colors at peak ($g-r\approx-0.5$ mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity ($M_{g,\mathrm{peak}}\approx-20.6$mag), a hot ($\gtrsim 40,000$K) featureless spectrum at peak light, and a luminous radio counterpart. At late times ($Δt>80$d) the radio luminosity of ZTF18abvkwla ($νL_ν\gtrsim 10^{40}$erg/s at 10 GHz, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy ($M\approx5\times10^{8}M_\odot$, $\mathrm{SFR}\approx7 M_\odot$/yr) that is moderately metal-enriched ($\log\mathrm{[O/H]} \approx 8.5$), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast-moving ejecta ($Γβc >0.38c$) and the optical from shock-interaction with confined dense material ($<0.07M_\odot$ in $\sim 10^{15}$cm). Compiling transients in the literature with $t_\mathrm{rise} <5$d and $M_\mathrm{peak}<-20$mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, and prospects for detecting accompanying X-ray and radio emission.
