About 155.8 million light years away, AT2023clx was initially identified in 2014 as a transient in the nucleus of the galaxy NGC 3799. In July 2023, it was classified as a tidal disruption event (TDE) with a maximum blackbody luminosity at a level of only 4.56 tredecillion erg/s.
Astronomers have realized that AT2023clx belongs to the faintest known tidal disruption event. Other than that, very little information is known about the properties of the closest optical TDE.
What Is a Tidal Disruption Event?
Tidal disruption events are astronomical phenomena which take place when a star passes close enough to a supermassive black hole and is pulled apart by its tidal forces. This happens in a galaxy roughly once every ten thousand years.
About half of the stellar debris continues on its original trajectory, while the remaining half becomes gravitationally bound and falls back towards the cosmic void. The bound stellar material forms an accretion which causes a short-lived flare of emission.
As the stellar debris are tidally disrupted and rained down on the black hole, radiation is emitted from the innermost region of accreting debris, which serves as an indicator of the presence of a tidal disruption event. Such extreme episodes serve as a vital tool in understanding the influence of black holes on their environment.
READ ALSO: Supermassive Black Hole Devours Distant Star in a Tidal Disruption Event, Shredding It to Bits
Gaining More Insight About AT2023clx
To learn more about this event, experts from the University of Turku in Finland performed an extensive analysis of tidal disruption events in optical, near-infrared, and ultraviolet bands. The result of their study is discussed in the paper "The fast transient AT 2023clx in the nearby LINER galaxy NGC 3799, as a tidal disruption event of a very low-mass star".
Led by Panos Charalampopoulo, the research team used different space telescopes and ground-based observing facilities. These include NASA's Swift spacecraft and the Nordic Optical Telescope (NOT). They also conducted a follow-up and thorough photometric and spectroscopic analysis of AT2023clx.
It was found that AT2023clx had a peak absolute magnitude of -18.25 mag in the g-band and a maximum bolometric luminosity at a level of 32.4 tredecillion erg/s. These figures place AT2023clx under intermediate luminosity tidal disruption event. Meanwhile, the mass of the supermassive black hole was estimated to be in the order of one million solar masses.
The study also reveals that AT2023clx rose to its peak within 10.4 days, making it the fastest rising tidal disruption event known to date. Scientists assume that such a fast rise was due to the disruption of a very low-mass star (below 0.1 solar masses) with an impact parameter of about 0.8.
The spectroscopic analysis also revealed a blue continuum which cools slowly, as well as broad Balmer and helium lines typically observed in tidal disruption events. Another common feature observed in AT2023clx is the slow narrowing of lines as their luminosity drops in time.
Additionally, the analysis also discovered a sharp, narrow emission peak at a rest wavelength of about 6353 Å, on top of the blue side of the broad hydrogen-alpha profile. This is the first time such a feature was observed in a tidal disruption event.
In summary, the scientists noted that AT2023clx was formed from the tidal disruption of a low-mass, small radius stellar body with low central concentration. It is close to full disruption but below the critical value. Furthermore, such a disruption is expected to show a rise and a shallower decline in the light curves than other disruptions.
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