A Massive Black Hole 0.8 kpc from the Host Nucleus Revealed by the Offset Tidal Disruption Event AT2024tvd

Yao, Y ORCID: 0000-0001-6747-8509, Chornock, R ORCID: 0000-0002-7706-5668, Ward, C ORCID: 0000-0002-4557-6682, Hammerstein, E ORCID: 0000-0002-5698-8703, Sfaradi, I ORCID: 0000-0003-0466-3779, Margutti, R ORCID: 0000-0003-4768-7586, Kelley, LZ ORCID: 0000-0002-6625-6450, Lu, W ORCID: 0000-0002-1568-7461, Liu, C ORCID: 0000-0002-7866-4531, Wise, J ORCID: 0000-0003-0733-2916, Sollerman, J ORCID: 0000-0003-1546-6615, Alexander, KD ORCID: 0000-0002-8297-2473, Bellm, EC ORCID: 0000-0001-8018-5348, Drake, AJ ORCID: 0000-0003-0228-6594, Fremling, C ORCID: 0000-0002-4223-103X, Gilfanov, M, Graham, MJ ORCID: 0000-0002-3168-0139, Groom, SL ORCID: 0000-0001-5668-3507, Hinds, KR ORCID: 0000-0002-0129-806X, Kulkarni, SR ORCID: 0000-0001-5390-8563 et al (2025) A Massive Black Hole 0.8 kpc from the Host Nucleus Revealed by the Offset Tidal Disruption Event AT2024tvd. The Astrophysical Journal Letters, 985 (2). ISSN 2041-8205

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Abstract

Tidal disruption events (TDEs) that are spatially offset from the nuclei of their host galaxies offer a new probe of massive black hole (MBH) wanderers, binaries, triples, and recoiling MBHs. Here we present AT2024tvd, the first off-nuclear TDE identified through optical sky surveys. High-resolution imaging with the Hubble Space Telescope shows that AT2024tvd is 0"914 ± 0"010 offset from the apparent center of its host galaxy, corresponding to a projected distance of 0.808 ± 0.009 kpc at z = 0.045. Chandra and Very Large Array observations support the same conclusion for the TDE's X-ray and radio emission. AT2024tvd exhibits typical properties of nuclear TDEs, including a persistent hot UV/optical component that peaks at Lbb ∼ 6 × 1043 erg s−1, broad hydrogen lines in its optical spectra, and delayed brightening of luminous (LX,peak ∼ 3 × 1043 erg s−1), highly variable soft X-ray emission. The MBH mass of AT2024tvd is 106±1 M⊙, at least 10 times lower than its host galaxy's central black hole mass (≳108 M⊙). The MBH in AT2024tvd has two possible origins: a wandering MBH from the lower-mass galaxy in a minor merger during the dynamical friction phase or a recoiling MBH ejected by triple interactions. Combining AT2024tvd with two previously known off-nuclear TDEs discovered in X-rays (3XMM J2150 and EP240222a), which likely involve intermediate-mass black holes in satellite galaxies, we find that the parent galaxies of all three events are very massive (∼1010.9 M⊙). This result aligns with expectations from cosmological simulations that the number of offset MBHs scales linearly with the host halo mass.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	25 April 2025
Date of first compliant Open Access:	3 June 2025
Date Deposited:	03 Jun 2025 15:57
Last Modified:	03 Jul 2025 13:00
DOI or ID number:	10.3847/2041-8213/add7de
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26514

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