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arXiv · 2309.05718

Discovery of An X-ray Photoionized Optical Nebula and A Radio Nebula Associated with the ULX NGC 4861 X-1

Hang Gong·Ryan Urquhart·Alexandr Vinokurov·Yu Bai·Antonio Cabrera-Lavers·Sergei Fabrika·Liang Wang·Jifeng Liu
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Abstract

We have conducted long-slit spectroscopic observations and analyzed archival radio data for the ultraluminous X-ray source (ULX) NGC 4861 X-1. Our spectral line analysis unveils that NGC 4861 X-1 is the fourth ULX situated within an X-ray photoionized nebula, following three previous findings made approximately two decades ago. Remarkably, we discover NGC 4861 X-1 also possesses a radio nebula emitting optically thin synchrotron radiation, which contradicts its X-ray photoionization and raises doubts about the four ULXs being a mere coincidence. Instead of gradually accumulating from different bands bit by bit, our multi-band discovery is made all at once. Moreover, we tentatively perceive a faint continuum spectrum of the optical nebula. Further observations are needed to ascertain its radio structures and verify the optical continuum.

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Hang Gong, Ryan Urquhart, Alexandr Vinokurov, Yu Bai, Antonio Cabrera-Lavers, Sergei Fabrika, Liang Wang, Jifeng Liu. 2023-09-11. Discovery of An X-ray Photoionized Optical Nebula and A Radio Nebula Associated with the ULX NGC 4861 X-1. https://arxiv.org/abs/2309.05718

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