The fast transient AT 2023clx in the nearby LINER galaxy NGC 3799 as a tidal disruption of a very low-mass star
: Charalampopoulos, P.; Kotak, R.; Wevers, T.; Leloudas, G.; Kravtsov, T.; Pursiainen, M.; Ramsden, P.; Reynolds, T. M.; Aamer, A.; Anderson, J. P.; Arcavi, I.; Cai, Y. -Z.; Chen, T. -W.; Dennefeld, M.; Galbany, L.; Gromadzki, M.; Gutierrez, C. P.; Ihanec, N.; Kangas, T.; Kankare, E.; Kool, E.; Lawrence, A.; Lundqvist, P.; Makrygianni, L.; Mattila, S.; Mueller-Bravo, T. E.; Nicholl, M.; Onori, F.; Sahu, A.; Smartt, S. J.; Sollerman, J.; Wang, Y.; Young, D. R.
Publisher: EDP SCIENCES S A
: LES ULIS CEDEX A
: 2024
: Astronomy and Astrophysics
: ASTRONOMY & ASTROPHYSICS
: ASTRON ASTROPHYS
: A350
: 689
: 29
: 0004-6361
: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202449296
: https://doi.org/10.1051/0004-6361/202449296
: https://research.utu.fi/converis/portal/detail/Publication/459124730
We present an extensive analysis of the optical and ultraviolet (UV) properties of AT 2023clx, the closest optical/UV tidal disruption event (TDE) to date (z = 0.01107), which occurred in the nucleus of the interacting low-ionization nuclear emission-line region (LINER) galaxy, NGC 3799. After correcting for the host reddening (E(B - V)(h) = 0.179 mag), we find its peak absolute g-band magnitude to be -18.03 +/- 0.07 mag, and its peak bolometric luminosity to be L-pk = (1.57 +/- 0.19)x10(43) erg s(-1). AT 2023clx displays several distinctive features: first, it rose to peak within 10.4 +/- 2.5 days, making it the fastest rising TDE to date. Our SMBH mass estimate of (M) over bar (BH) approximate to 10(6.0) M-circle dot -estimated using several standard methods- rules out the possibility of an intermediate-mass BH as the reason for the fast rise. Dense spectral follow-up reveals a blue continuum that cools slowly and broad Balmer and He II lines as well as weak He I lambda lambda 5876,6678 emission features that are typically seen in TDEs. The early, broad (width similar to 15 000 km s(-1)) profile of H alpha matches theoretical expectations from an optically thick outflow. A flat Balmer decrement (L-H alpha/L-H beta similar to 1.58) suggests that the lines are collisionally excited rather than being produced via photoionisation, in contrast to typical active galactic nuclei. A second distinctive feature, seen for the first time in TDE spectra, is a sharp, narrow emission peak at a rest wavelength of similar to 6353 angstrom. This feature is clearly visible up to 10 d post-peak; we attribute it to clumpy material preceding the bulk outflow, which manifests as a high-velocity component of H alpha (-9584 km s(-1)). Its third distinctive feature is the rapid cooling during the first similar to 20 days after peak, reflected as a break in the temperature evolution. Combining these findings, we propose a scenario for AT 2023clx involving the disruption of a very low-mass star (less than or similar to 0.1 M-circle dot) with an outflow launched in our line of sight and with disruption properties that led to efficient circularisation and prompt accretion disc formation, observed through a low-density photosphere.
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P.C. and R.K. acknowledges support via the Research Council of Finland (grant 340613). G.L. is supported by a research grant (19054) from VILLUM FONDEN. PR acknowledges support from STFC grant 2742655. TR and SM acknowledge support from the Research Council of Finland project 350458. AA is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948381). This work was funded by ANID, Millennium Science Initiative, ICN12_009. I.A. acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement number 852097), from the Israel Science Foundation (grant number 2752/19), from the United States – Israel Binational Science Foundation (BSF; grant number 2018166), and from the Pazy foundation (grant number 216312). Y.-Z. Cai is supported by the National Natural Science Foundation of China (NSFC, Grant No. 12303054), the Yunnan Fundamental Research Projects (Grant No. 202401AU070063) and the International Centre of Supernovae, Yunnan Key Laboratory (No. 202302AN360001). TWC acknowledges the Yushan Young Fellow Program by the Ministry of Education, Taiwan for the financial support. L.G. and T.E.M.B. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, and the European Union Next Generation EU/PRTR funds under the 2021 Juan de la Cierva program FJC2021-047124-I and the PID2020-115253GA-I00 HOSTFLOWS project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016, and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M , and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. CPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2020-115253GA-I00 HOSTFLOWS project, and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. MN is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948381) and by UK Space Agency Grant No. ST/Y000692/1. FO acknowledges support from MIUR, PRIN 2020 (grant 2020KB33TP) “Multimessenger astronomy in the Einstein Telescope Era (METE)”. M.P. acknowledges support from a UK Research and Innovation Fellowship (MR/T020784/1). A.N. acknowledges the Warwick Astrophysics PhD prize scholarship made possible thanks to a generous philanthropic donation. SJS acknowledges funding from STFC Grants ST/X006506/1, ST/T000198/1 and ST/X001253/1. YW acknowledges support from the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB0550200).
