A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Infrared observations reveal the reprocessing envelope in the tidal disruption event AT 2019azh
Tekijät: Reynolds, Thomas M.; Thomsen, Lars; Mattila, Seppo; Nagao, Takashi; Anderson, Joseph P.; Bauer, Franz E.; Charalampopoulos, Panos; Dai, Lixin; Faris, Sara; Gromadzki, Mariusz; Gutiérrez, Claudia P.; Kuncarayakti, Hanin; Inserra, Cosimo; Kankare, Erkki; Kravtsov, Timo; Moldon, Javier; Moran, Shane; Pérez Torres, Miguel; Wiseman, Phil; van Velzen, Sjoert
Kustantaja: EDP Sciences
Julkaisuvuosi: 2026
Lehti: Astronomy and Astrophysics
Artikkelin numero: A139
Vuosikerta: 708
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202556056
Julkaisun avoimuus kirjaamishetkellä: Avoimesti saatavilla
Julkaisukanavan avoimuus : Kokonaan avoin julkaisukanava
Verkko-osoite: https://doi.org/10.1051/0004-6361/202556056
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/523437712
Rinnakkaistallenteen lisenssi: CC BY
Rinnakkaistallennetun julkaisun versio: Kustantajan versio
Context.
Tidal disruption events (TDEs) are expected to release much of their energy in the far-ultraviolet (UV), which we do not observe directly. However, infrared (IR) observations can observe re-radiation of the optical/UV emission from dust, and if this dust is observed in the process of sublimation, we can infer the un-observed UV radiated energy. Tidal disruption events have also been predicted to show spectra shallower than a blackbody in the IR, but this has not yet been observed.
Aims.
We present IR observations of the TDE AT 2019azh that span from −3 d before the peak until > 1750 d after. We evaluate these observations for consistency with dust emission or direct emission from the TDE.
Methods.
We fitted the IR data with a modified blackbody associated with dust emission. We compared the UV+optical+IR data with simulated spectra produced from general relativistic radiation magnetohydrodynamics simulations of super-Eddington accretion. We modelled the data at later times (> 200 d) as an IR echo.
Results.
The IR data at the maximum light cannot be self-consistently fitted with dust emission. Instead, the data can be better fitted with a reprocessing model, with the IR excess arising due to the absorption opacity being dominated by free-free processes in the dense reprocessing envelope. We infer a large viewing angle of ∼60°, which is consistent with previously reported X-ray observations, and a tidally disrupted star with a mass > 2 M⊙. The IR emission at later times is consistent with cool dust emission. We modelled these data as an IR echo and found that the dust is distant (0.65 pc) and clumpy, with a low covering factor. We show that TDEs can have an IR excess that does not arise from dust and that IR observations at early times can constrain the viewing angle for the TDE in the unified model. Near-IR observations are therefore essential to distinguish between hot dust and a non-thermal IR excess.
Ladattava julkaisu This is an electronic reprint of the original article. |  |
Julkaisussa olevat rahoitustiedot:
T.M.R is part of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140. T.M.R and S. Mattila acknowledge support from the Research Council of Finland project 350458. T.N. and H.K. acknowledge support from the Research Council of Finland projects 324504, 328898, and 353019. S. Moran is funded by Leverhulme Trust grant RPG-2023-240. LT and LD acknowledge support from the National Natural Science Foundation of China and the Hong Kong Research Grants Council (N_HKU782/23, HKU17305124). 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 PID2023-151307NB-I00 SNNEXT 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.FEB acknowledges support from ANID-Chile BASAL CATA FB210003, FONDECYT Regular 1241005, and Millennium Science Initiative, AIM23-0001. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This publication makes use of data products from the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), which is a joint project of the Jet Propulsion Laboratory/California Institute of Technology and the University of California, Los Angeles. NEOWISE is funded by the National Aeronautics and Space Administration.
