AI 中文总结
研究与离轴相对论性喷流相关的多波段瞬变源AT 2019ijn，它来自矮星系，光学耀斑上升快下降浅，后续有高能射电对应体。综合特性排除已知恒星爆炸类型，倾向于喷流潮汐瓦解事件，确定喷流发射情况，为发现类似瞬变源提供新窗口。
AI 中文摘要
许多最亮的河外瞬变源源于物质通过核心坍缩、恒星合并或恒星潮汐瓦解落入黑洞。一些产生高能多波段辐射，呈现短的蓝光耀斑和明亮持久的射电余辉。在罕见情况下，这些还会发射强大的相对论性喷流，几乎仅通过高能辐射在轴向上被探测到。本文报告了在甚大天线阵巡天中发现的射电瞬变源AT 2019ijn，它与一个离轴的强大相对论性喷流相关，并伴有一个发光的光学瞬变源。AT 2019ijn来自红移z = 0.273的恒星形成矮星系，其光学耀斑上升快（静止系上升时间约7天）且下降浅（静止系下降时间>38天），一年后出现一个高能（能量约2×10^52尔格）的射电对应体，持续超过6年。这些综合特性前所未闻，排除了已知的由核心坍缩驱动的恒星爆炸类型。相反其暗示的黑洞吸积和相关离轴喷流意味着一个奇特的黑洞 - 恒星合并或由10^4 - 10^6太阳质量黑洞引发的喷流潮汐瓦解事件（TDE）。本文倾向于TDE，确定了喷流发射的发生情况，低红移使得能够对晚期演化进行限制，与之前的事件形成对比。即将到来的射电巡天将为进一步发现类似AT 2019ijn的离轴相对论性瞬变源提供前所未有的新窗口。
英文摘要
Many of the most luminous extragalactic transients originate from the accretion of material onto a black hole (BH) via core-collapse, stellar mergers, or the tidal disruption of a star. Some produce energetic multi-wavelength emission, displaying short, blue optical flares and bright, long-lived radio afterglows. In rare cases, these have also launched powerful relativistic jets almost exclusively detected on-axis via high-energy emission. Here we report AT 2019ijn, a radio transient discovered in the Very Large Array Sky Survey, associated with a powerful relativistic jet viewed off-axis and accompanied by a luminous ($νL_{ν, opt} \sim 10^{44}$ erg/s) optical transient. Originating from a star-forming dwarf galaxy at z = 0.273, AT 2019ijn's optical flare exhibited a fast rise ($t_{rise, rest} \sim 7$ d) and shallow decline ($t_{dec, rest} > 38$ d), followed a year later by an energetic ($E \sim 2\times10^{52}$ erg) radio counterpart persisting for $>6$ years. These combined properties are unprecedented and preclude known classes of stellar explosion powered by core-collapse. Instead, the implied accretion onto a BH and associated off-axis jet invokes an exotic BH-stellar merger or a jetted tidal disruption event (TDE) by a $10^4 - 10^6 M_\odot$ black hole. Favoring a TDE, this work determines the jet-launching occurrence, with the low redshift allowing constraints on the late-time evolution in contrast to prior events. Upcoming radio sky surveys will offer an unprecedented new window for further discovery of AT 2019ijn-like off-axis relativistic transients.
Comments57 pages, 10 figures, 3 tables. Submitted to Nature Astronomy
