We present radio observations of 23 optically discovered tidal disruption events (TDEs) on timescales of ∼500–3200 days postdiscovery. We detect nine new TDEs that did not have detectable radio emission at earlier times, indicating a late-time brightening after several hundred (and up to 2300) days; an additional seven TDEs exhibit radio emission whose origin is ambiguous or may be attributed to the host galaxy or an active galactic nucleus. We also report a new rising component in one TDE previously detected in the radio at ∼10³ days. While the radio emission in some of the detected TDEs peaked on a timescale ≈2–4 yr, over half of the sample still show rising emission. The range of luminosities for the sample is ∼10³⁷–10³⁹ erg s⁻¹, about 2 orders of magnitude below the radio luminosity of the relativistic TDE Sw J1644+57. Our data set indicates ∼40% of all optical TDEs are detected in radio hundreds to thousands of days after discovery, and that this is probably more common than early radio emission peaking at ∼10² days. Using an equipartition analysis, we find evidence for a delayed launch of the radio-emitting outflows, with delay timescales of ∼500–2000 days, inferred velocities of ≈0.02–0.15c, and kinetic energies of ∼10⁴⁷–10⁴⁹ erg. We rule out off-axis relativistic jets as a viable explanation for this population, and conclude delayed outflows are a more likely explanation, possibly from delayed disk formation. We conclude late radio emission marks a fairly ubiquitous but heretofore overlooked phase of TDE evolution.

中文翻译：

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潮汐扰乱事件造成的无处不在的晚期无线电发射


我们展示了 23 个光学发现的潮汐破坏事件 (TDE) 的无线电观测结果，时间尺度为发现后约 500-3200 天。我们检测到 9 个新的 TDE，它们在早期没有可检测到的无线电发射，这表明在数百（最多 2300）天后出现了晚期增亮；另外七个 TDE 表现出无线电发射，其来源不明确或可能归因于宿主星系或活跃的星系核。我们还报告了先前在 ∼10 ³天的无线电中检测到的一个 TDE 中的一个新的上升分量。虽然一些检测到的 TDE 中的无线电发射在约 2-4 年的时间尺度上达到峰值，但超过一半的样本仍然显示出不断上升的发射。样本的光度范围为~10 ³⁷ –10 ³⁹ erg s ^-1 ，比相对论性 TDE Sw J1644+57 的射电光度低约 2 个数量级。我们的数据集表明，约 40% 的光学 TDE 在发现后数百至数千天在无线电中被检测到，这可能比约 10 ²天的早期无线电发射峰值更常见。通过均分分析，我们找到了射电辐射流延迟发射的证据，延迟时间尺度约为 500-2000 天，推断速度约为 0.02-0.15c，动能约为 10 ⁴⁷ –10 ⁴⁹ erg。我们排除了离轴相对论性喷流作为该群体的可行解释，并得出结论，延迟流出是更可能的解释，可能来自延迟的磁盘形成。我们得出的结论是，晚期无线电发射标志​​着 TDE 演变的一个相当普遍但迄今为止被忽视的阶段。