@article{cbac9eae9833491d889c232ef639a10f,
title = "Mid-infrared Flare of TDE Candidate PS16dtm: Dust Echo and Implications for the Spectral Evolution",
abstract = "PS16dtm was classified as a candidate tidal disruption event in a dwarf Seyfert 1 galaxy with a low-mass black hole (∼106 M⊙) and has presented various intriguing photometric and spectra characteristics. Using the archival Wide-field Infrared Survey Explorer and the newly released NEOWISE data, we found that PS16dtm is experiencing a mid-infrared (MIR) flare that started ∼11 days before the first optical detection. Interpreting the MIR flare as a dust echo requires close pre-existing dust with a high covering factor and suggests that the optical flare may have brightened slowly for some time before it became bright detectable from the ground. More evidence is given at the later epochs. At the peak of the optical light curve, the new inner radius of the dust torus has grown to a much larger size (i.e., a factor of seven of the initial radius) due to the strong radiation field. At ∼150 days after the first optical detection, the dust temperature has dropped well below the sublimation temperature. Other peculiar spectral features shown by PS16dtm are the transient, prominent Fe II emission lines and outflows indicated by broad absorption lines detected during the optical flare. Our model explains the enhanced Fe II emission from iron that is newly released from the evaporated dust. The observed broad absorption line outflow could be explained by accelerated gas in the dust torus due to the radiation pressure.",
keywords = "galaxies: active, galaxies: individual (PS16dtm), galaxies: nuclei",
author = "Ning Jiang and Tinggui Wang and Lin Yan and Ting Xiao and Chenwei Yang and Liming Dou and Huiyuan Wang and Roc Cutri and Amy Mainzer",
note = "Funding Information: We thank the anonymous referee for a thorough report and many constructive comments that help us improve this work. We thank SuboDong and Ben Shappee for kindly providing us the ASAS-SN data when we prepared the draft. We thank Nicholas Stone for his very nice and timely comments on the interpretation of the early MIR detection after the draft was posted on arXiv. This work is supported by the National Basic Research Program of China (grant No. 2015CB857005), NSFC (NSFC-116203021, NSFC-11421303, NSFC-11303008, and NSFC-11733001), Joint Research Fund in Astronomy (U1431229, U1531245, and U1731104) under cooperative agreement between the NSFC and the CAS and the Fundamental Research Funds for the Central Universities. This research makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This research also makes use of data products from NEOWISE-R, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of the National Aeronautics and Space Administration. Funding Information: This work is supported by the National Basic Research Program of China (grant No. 2015CB857005), NSFC (NSFC-116203021, NSFC-11421303, NSFC-11303008, and NSFC-11733001), Joint Research Fund in Astronomy (U1431229, U1531245, and U1731104) under cooperative agreement between the NSFC and the CAS and the Fundamental Research Funds for the Central Universities. This research makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This research also makes use of data products from NEOWISE-R, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of the National Aeronautics and Space Administration. Publisher Copyright: {\textcopyright} 2017. The American Astronomical Society.",
year = "2017",
month = nov,
day = "20",
doi = "10.3847/1538-4357/aa93f5",
language = "English (US)",
volume = "850",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",
}