SDSS image of the host galaxy NGC 3799, before the transient occurs. The galactic core where the TDE occurred is marked with a green cross and is also shown in an enlarged box in the upper right corner. Credit: arXiv (2024). DOI: 10.48550/arxiv.2401.11773
An international team of astronomers has made multi-wavelength observations of AT 2023clx, the closest tidal disturbance event (TDE) to Earth. Results of the observation campaign, published on January 22 on the pre-print server arXivprovide important information about the properties of this TDE.
TDEs are astronomical phenomena that occur when a star passes close enough to a supermassive black hole and is separated by tidal forces from the black hole, thereby causing a disruption process. This tidally disrupted stellar debris begins to rain down on the black hole and radiation emerges from the innermost region of the accreting debris, which is an indicator of the presence of a TDE.
Located some 155.8 million light years away, in the core of the galaxy NGC 3799, AT 2023clx is the closest known optical TDE. It was initially identified as a transient in 2014 and classified as a TDE in July 2023. With peak blackbody luminosity at a level of only 4.56 tredecillion erg/s, AT 2023clx is one of the disruption events in lowest known tides.
Since AT 2023clx is a recently discovered TDE, very little is known about its properties. This is why a group of astronomers, led by Panos Charalampopoulos from the University of Turku in Finland, carried out an in-depth study of TDE in the optical, near-infrared and ultraviolet bands. To this end, they used various space telescopes and ground-based observation facilities, including NASA’s Swift spacecraft and the Nordic Optical Telescope (NOT).
“In this paper, we present the monitoring and in-depth photometric and spectroscopic analysis of AT 2023clx,” the researchers write.
Observations revealed that AT 2023clx had a maximum absolute magnitude of -18.25 mag in the g-band and a maximum bolometric luminosity at a level of 32.4 tredecillion erg/s. This makes it a TDE of intermediate brightness. The mass of the supermassive black hole has been estimated at around 1 million solar masses.
According to the study, AT 2023clx peaked in 10.4 days, making it the fastest rising TDE known to date. Astronomers assume that such a rapid rise was caused by the disruption of a very low-mass star (less than 0.1 solar masses) with an impact parameter of around 0.8.
Spectroscopy revealed a slowly cooling blue continuum and broad Balmer and helium lines, which is typically observed during tidal disruption events. The lines slowly become narrower over time as their brightness decreases, which is also typically observed in known TDEs.
Observations of AT 2023clx also revealed a sharp, narrow emission peak at a rest wavelength of about 6,353 Å, above the blue side of the broad hydrogen alpha profile. This is the first time such functionality has been found in a TDE.
Summarizing the results, the researchers note that AT 2023clx is the result of tidal disruption of a low-mass, small-radius star with a low central concentration, close to complete disruption but yet below the critical value. . They add that such a disturbance should show a stronger increase and a shallower fall in light curves than other disturbances.
More information:
P. Charalampopoulos et al, The fast transient AT 2023clx in the neighboring LINER galaxy NGC 3799, as a tidal disruption event of a very low mass star, arXiv (2024). DOI: 10.48550/arxiv.2401.11773
Journal information:
arXiv
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