论文标题
Asassn-19dj的发现和随访：极端季后星系中的X射线和UV发光TDE
Discovery and Follow-up of ASASSN-19dj: An X-ray and UV Luminous TDE in an Extreme Post-Starburst Galaxy
论文作者
论文摘要
我们介绍了Asassn-19dj的观察，这是附近的潮汐破坏事件（TDE），该事件是在恒星后星系中发现的，由All-Sky Supermated Supernovae（ASAS-SN）以D $ \ simeq98 $ mpc的距离为d $ \ simeq98 $ mpc。我们使用高效率，多波长光谱和光度法观察到相对于峰紫外线（UV）/光发射的Asassn-19dj从$ -21到392 d。从ASAS-SN $ g $ band数据中，我们确定TDE于2019年2月6.8日开始亮起，在前16 D中，上升与Flux $ \ propto t^2 $ powerlaw一致。 ASASSN-19DJ在2019年3月6.5日（MJD = 58548.5）以$ l =（6.2 \ pm 0.2）\ times 10^{44} {44} \ text {erg s}^{ - 1} $达到顶峰。 X射线通量最初在X射线中保持大致恒定，并在紫外光/光学中缓慢褪色，峰值升至峰值后的$ \ sim $ \ sim $ \ sim $ \ sim，这是由于X射线发射区域的膨胀而导致的。延迟X射线发射是由黑体很好地安装的，有效半径为$ \ sim1 \ times 10^{12} \ text {cm} $，温度为$ \ sim6 \ sim6 \ times 10^{5} {5} \ text {k} $。 X射线硬度比在亮度后变得更柔软，然后随着X射线褪色而恢复到更硬的状态。对Catalina实时瞬态调查图像的分析显示，核爆发大约早于14.5年，平稳下降和亮度为$ L_V \ geq1.4 \ times 10^{43} $ erg s $^{ - 1} $，尽管耀斑的性质尚不清楚。 Asassn-19dj发生在尚未举办TDE的最极端的巨星星系中，lick H $δ_{a} $ = $ 7.67 \ pm0.17 $Å。
We present observations of ASASSN-19dj, a nearby tidal disruption event (TDE) discovered in the post-starburst galaxy KUG 0810+227 by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d $\simeq98$ Mpc. We observed ASASSN-19dj from $-$21 to 392 d relative to peak ultraviolet (UV)/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From the ASAS-SN $g$-band data, we determine that the TDE began to brighten on 2019 February 6.8 and for the first 16 d the rise was consistent with a flux $\propto t^2$ power-law. ASASSN-19dj peaked in the UV/optical on 2019 March 6.5 (MJD = 58548.5) at a bolometric luminosity of $L = (6.2 \pm 0.2) \times 10^{44} \text{ erg s}^{-1}$. Initially remaining roughly constant in X-rays and slowly fading in the UV/optical, the X-ray flux increased by over an order of magnitude $\sim$225 d after peak, resulting from the expansion of the X-ray emitting region. The late-time X-ray emission is well fitted by a blackbody with an effective radius of $\sim1 \times 10^{12} \text{ cm}$ and a temperature of $\sim6 \times 10^{5} \text{ K}$. The X-ray hardness ratio becomes softer after brightening and then returns to a harder state as the X-rays fade. Analysis of Catalina Real-Time Transient Survey images reveals a nuclear outburst roughly 14.5 yr earlier with a smooth decline and a luminosity of $L_V\geq1.4 \times 10^{43}$ erg s$^{-1}$, although the nature of the flare is unknown. ASASSN-19dj occurred in the most extreme post-starburst galaxy yet to host a TDE, with Lick H$δ_{A}$ = $7.67\pm0.17$ Å.
