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The UV/optical peak and X-ray brightening in TDE candidate AT2019azh: A case of stream-stream collision and delayed accretion by Liu, Xiao-Long; Dou, Li-Ming; Chen, Jin-Hong; Shen, Rong-Feng is a scholarly article available to read on EtoBox.

What is The UV/optical peak and X-ray brightening in TDE candidate AT2019azh: A case of stream-stream collision and delayed accretion about?

We present and analyze the optical/UV and X-ray observations of a nearby tidal disruption event (TDE) candidate AT2019azh, spanning from $\sim$ 30 d before to $\sim$ 400 d after its early optical peak. The X-rays show a late brightening by a factor of $\sim$ 30-100 around 200 days after discovery, while the UV/opticals continuously decayed. The early X-rays show two flaring episodes of variation, temporally uncorrelated with the early UV/opticals. We found a clear sign of X-ray hardness evolution, i.e., the source is harder at early times, and becomes softer as it brightens later. The drastically different temporal behaviors in X-rays and UV/opticals suggest that the two bands are physically distinct emission components, and probably arise from different locations. These properties argue against the reprocessing of X-rays by any outflow as the origin of the UV/optical peak. The full data are best explained by a two-process scenario, in which the UV/optical peak is produced by the debris stream-stream collisions during the circularization phase; some shocked gas with low angular momentum forms an early, low-mass 'precursor' accretion disk which emits the early X-rays. The major body

Author

Liu, Xiao-Long; Dou, Li-Ming; Chen, Jin-Hong; Shen, Rong-Feng

Published

2019

Language

EN