TY - JOUR
T1 - The fast transient AT 2023clx in the nearby LINER galaxy NGC 3799 as a tidal disruption of a very low-mass star
AU - Charalampopoulos, P.
AU - Kotak, R.
AU - Wevers, T.
AU - Leloudas, G.
AU - Kravtsov, T.
AU - Pursiainen, M.
AU - Ramsden, P.
AU - Reynolds, T. M.
AU - Aamer, A.
AU - Anderson, J. P.
AU - Arcavi, I.
AU - Cai, Y. -Z.
AU - Chen, T. -W.
AU - Dennefeld, M.
AU - Galbany, L.
AU - Gromadzki, M.
AU - Gutierrez, C. P.
AU - Ihanec, N.
AU - Kangas, T.
AU - Kankare, E.
AU - Kool, E.
AU - Lawrence, A.
AU - Lundqvist, P.
AU - Makrygianni, L.
AU - Mattila, S.
AU - Mueller-Bravo, T. E.
AU - Nicholl, M.
AU - Onori, F.
AU - Sahu, A.
AU - Smartt, S. J.
AU - Sollerman, J.
AU - Wang, Y.
AU - Young, D. R.
PY - 2024/9/24
Y1 - 2024/9/24
N2 - 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 Lpk = (1.57 ± 0.19)×1043 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 M̄BH ≈ 106.0 M⊙ –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 Iλλ5876,6678 emission features that are typically seen in TDEs. The early, broad (width ∼15 000 km s−1) profile of Hα matches theoretical expectations from an optically thick outflow. A flat Balmer decrement (LHα/LHβ ∼ 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 ∼6353 Å. 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 Hα (−9584 km s−1). Its third distinctive feature is the rapid cooling during the first ∼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 (≲0.1 M⊙) 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.
AB - 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 Lpk = (1.57 ± 0.19)×1043 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 M̄BH ≈ 106.0 M⊙ –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 Iλλ5876,6678 emission features that are typically seen in TDEs. The early, broad (width ∼15 000 km s−1) profile of Hα matches theoretical expectations from an optically thick outflow. A flat Balmer decrement (LHα/LHβ ∼ 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 ∼6353 Å. 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 Hα (−9584 km s−1). Its third distinctive feature is the rapid cooling during the first ∼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 (≲0.1 M⊙) 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.
KW - Black hole physics
KW - Galaxies: nuclei
KW - Methods: observational
UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=pure_uoe&SrcAuth=WosAPI&KeyUT=WOS:001321216400017&DestLinkType=FullRecord&DestApp=WOS_CPL
U2 - 10.1051/0004-6361/202449296
DO - 10.1051/0004-6361/202449296
M3 - Article
SN - 0004-6361
VL - 689
SP - 1
EP - 29
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
M1 - A350
ER -