ATLAS22kjn（AT 2022fpx）：具有早期光曲线鼓包和中红外尘埃回波的日冕线发射体
ATLAS22kjn (AT 2022fpx): A Coronal Line Emitter with an Early Light Curve Bump and Mid-Infrared Dust Echo
AI总结：
该研究分析了TDE ATLAS22kjn的多波段观测数据，发现其早期光曲线鼓包与中红外尘埃回波特征，确定日冕线区域位置，证实多波段及CLEs对研究TDE的重要性。
AI中文摘要：
我们对ATLAS22kjn（AT 2022fpx）开展分析，该天体的高电离日冕线（CLs）和峰值前光曲线鼓包为探究驱动潮汐瓦解事件（TDEs）的物理机制提供了独特契机。除日冕线外，其光学光谱呈现典型TDE特征，包括强蓝连续谱及宽的巴耳末线、He II线。日冕线出现在紫外/光学光曲线峰值之前，比X射线探测早约300天，且在X射线不再被探测后仍持续存在，表明X射线辐射在早期和晚期均被遮蔽。利用日冕线光度，我们限制了电离源的温度演化，发现在500天内温度下降幅度不超过10%。在紫外/光学光曲线中，我们观测到一个持续9（+4/-2）天的鼓包，其峰值出现在主耀斑峰值前125（+5/-3）个静止帧日。尽管我们无法明确确定该鼓包的起源，但发现其时标和光度与流-流碰撞或风-流碰撞产生的前驱特征的理论预测最为吻合。ATLAS22kjn在中红外（MIR）光曲线中还显示出显著的尘埃回波，表明尘埃覆盖分数f_c≈0.40±0.03，与其他日冕线发射TDE的覆盖分数相似。通过对ATLAS22kjn的多波段观测，我们估算了其核环境中发射区域的大小和相对半径，确定日冕线区域位于宽线区与中红外发射尘埃之间。ATLAS22kjn证明了多波段和早期观测的重要性，以及日冕线发射体（CLEs）在表征TDE原本不可观测的极紫外/超软X射线辐射方面的实用性。
英文摘要：
We present an analysis of ATLAS22kjn (AT 2022fpx), whose high-ionisation coronal lines (CLs) and pre-peak light curve bump provide distinctive opportunities to investigate the physical mechanisms powering tidal disruption events (TDEs). In addition to CLs, the optical spectra show common TDE features, including a strong, blue continuum and broad Balmer and He II lines. The CLs appear before UV/optical light curve peak, preceding the detection of X-rays by $\sim 300$ days and persisting after X-rays are no longer detected, suggesting the X-ray emission is obscured at both early and late times. Using the CL luminosities, we constrain the temperature evolution of the ionising source, finding a decrease of $\lesssim 10 \%$ over 500 days. In the UV/optical light curve, we observe a $9 \substack{+4 \\ -2}$ day bump that peaks $125 \substack{+5 \\ -3}$ rest-frame days before the peak of the main flare. Although we cannot definitively determine the origins of the bump, we find that its timescale and luminosity are most consistent with theoretical predictions for a precursor feature produced by a stream-stream collision or a wind-stream collision. ATLAS22kjn also shows a prominent dust echo in its mid-infrared (MIR) light curves, indicating a high dust covering fraction $f_c \simeq 0.40 \pm 0.03$, similar to the covering fractions of other CL-emitting TDEs. From the multi-wavelength observations of ATLAS22kjn, we estimate the size and relative radii of the emission regions in its nuclear environment and determine that the CL region lies between the broad line region and the MIR-emitting dust. ATLAS22kjn demonstrates the importance of multi-wavelength and early-time observations, and the utility of CLEs in characterising the otherwise unobservable EUV/ultrasoft X-ray emission of TDEs.
