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arXiv 2004.01517astro-ph.GAastro-ph.HE
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活动星系核SDSS J022700中发现的一个潮汐破裂事件候选者.77-042020.6

A Tidal Disruption Event Candidate Discovered in the Active Galactic Nucleus SDSS J022700.77-042020.6

Zhu Liu, Dongyue Li, He-Yang Liu, Youjun Lu, Weimin Yuan, Liming Dou, Rong-Feng Shen

摘要:

我们报告了在活动星系核SDSS J022700.77-042020.6中发现的潮汐破裂事件(TDE)候选者。J 0227 -0420的通量在2009年下半年突然增加,这在长期光学、紫外和近红外光变曲线中清晰可见。在NUV和光学u、g、r、i光变曲线中,在初始下降之后出现平台阶段。此外,我们发现可能的证据表明,在NUV波段的平台阶段可能落后于光学的约70-80天,也有一个更短的持续时间,即$\sim$ 7-15天对$\sim$ 40-50天。长期NUV/光学(平台期后)、NIR和MIR光变曲线可以用$L(t)\propto t^{-β}$的形式很好地表征,与TDE的预期一致。如果恒星流以不同的半径与预先存在的活动星系核盘碰撞,则可以解释高原现象。虽然整体回退率降低,但外盘中的物质逐渐向内漂移,并增加了内部区域的局部吸积率,从而产生光学和紫外平台。光学平台和NUV平台之间可能的滞后则可归因于粘度延迟。近红外$J, H, K_s$谱带的指数$β$($\sim1.4-3.3$)比紫外/光学谱带($\sim0.7-1.3$)和中红外谱带($\sim0.9-1.8$)的指数$β$更陡,这可能表明尘埃环内部区域的一定比例的尘埃可能在TDE阶段升华。我们的研究结果表明,由于恒星碎片和预先存在的磁盘之间的碰撞,发生在AGN的TDEs的光变曲线可能会显示出独特的功能,这可能会揭示吸积过程的新的光变曲线。

英文摘要:

We report the discovery of a Tidal Disruption Event (TDE) candidate occurring in the Active Galactic Nucleus SDSS J022700.77-042020.6. A sudden increase in flux of J0227-0420 during the second half of 2009 is clearly shown in the long-term optical, UV, and NIR light curves. A plateau phase, following an initial decline, is seen in the NUV and optical u, g, r, i light curves. Moreover, we find possible evidence that the plateau phase in the NUV band may lag behind the optical ones by approximately 70-80 days with also a much shorter duration, i.e. $\sim$7-15 days against $\sim$40-50 days. The long-term NUV/optical (after the plateau phase), NIR and MIR light curves can be well characterized with a form of $L(t)\propto t^{-β}$, consistent with the expectation of a TDE. The plateaus can be explained if the stellar streams collide with the pre-existing AGN disk at different radii. Though the overall fallback rate decreases, the material in the outer disk gradually drifts inward and increases the local accretion rate at the inner region, producing the optical and UV plateaus. The possible lag between the optical and NUV plateaus can then be attributed to viscosity delay. The index $β$ of the NIR $J, H, K_s$ bands ($\sim1.4-3.3$) is steeper than that of the UV/optical ($\sim0.7-1.3$) and MIR bands ($\sim0.9-1.8$), which may suggest that a certain fraction of the dust in the inner region of the dusty torus may be sublimated during the TDE phase. Our results indicate that, due to collisions between stellar debris and pre-existing disk, the light curves of TDEs occurring in AGN may show distinctive features, which may shed new light on the accretion process.

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