Observations Reveal Unique Characteristics of ASASSN-20hx Nuclear Transient

Recent observations of ASASSN-20hx, a nearby ambiguous nuclear transient discovered in the galaxy NGC 6297, have revealed significant findings regarding its characteristics and behavior. The study, titled "The Curious Case of ASASSN-20hx: A Slowly-Evolving, UV and X-ray Luminous, Ambiguous Nuclear Transient," was conducted by Jason T. Hinkle and a team of researchers.

The team utilized high-cadence, multi-wavelength spectroscopy and photometry to monitor ASASSN-20hx from 30 days before to 275 days after its peak ultraviolet and optical emissions. The observations indicated that ASASSN-20hx began to brighten on June 22, 2020, reaching its peak luminosity of approximately 3.15 x 10^43 erg/s on July 22, 2020. Notably, the decline in brightness following this peak was slower than any previously observed tidal disruption event (TDE).

In addition to its optical characteristics, the X-ray luminosity of ASASSN-20hx increased significantly, reaching about 1.5 x 10^42 erg/s, before gradually declining. The X-ray emission was characterized by a power law with a photon index between 2.3 and 2.6. However, both optical and near-infrared spectra lacked the expected emission lines typically associated with known classes of nuclear transients.

The findings suggest that ASASSN-20hx exhibits features common to both TDEs and active galactic nuclei (AGNs), yet it does not fit neatly into either category based on the current data. This ambiguity raises important questions about the nature of such transients and their classification within astrophysical phenomena.

The implications of this research extend to our understanding of nuclear transients and their behaviors, potentially influencing future studies in high-energy astrophysics. The paper can be cited as follows: Hinkle, J. T., Holoien, T. W.-S., Shappee, B. J., et al. (2021). The Curious Case of ASASSN-20hx: A Slowly-Evolving, UV and X-ray Luminous, Ambiguous Nuclear Transient. arXiv:2108.03245.