TY - JOUR
T1 - A Two-zone Accretion Disk in the Changing-look Active Galactic Nucleus 1ES 1927+654
T2 - Physical Implications for Tidal Disruption Events and Super-Eddington Accretion
AU - Li, Ruancun
AU - Ho, Luis C.
AU - Ricci, Claudio
AU - Trakhtenbrot, Benny
N1 - Publisher Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
PY - 2024/11/1
Y1 - 2024/11/1
N2 - The properties of slim accretion disks, while crucial for our understanding of black hole growth, have yet to be studied extensively observationally. We analyze the multiepoch broadband spectral energy distribution of the changing-look active galactic nucleus 1ES 1927+654 to derive the properties of its complex, time-dependent accretion flow. The accretion rate decays as M ̇ ∝ t − 1.53 , consistent with the tidal disruption of a 1.1 M ⊙ star. Three components contribute to the spectral energy distribution: a central overheated zone resembling a slim disk, an outer truncated thin disk, and a hot corona. Photon trapping in the slim disk triggered by the high initial M ̇ was characterized by a low radiation efficiency (3%), which later more than doubled (8%) after M ̇ dropped sufficiently low for the disk to transition to a geometrically thin state. The blackbody temperature profile T ∝ R −0.60 for the inner overheated zone matches the theoretical expectations of a slim disk, while the effective temperature profile of T ∝ R −0.69 for the outer zone is consistent with the predictions of a thin disk. Both profiles flatten toward the inner boundary of the disk as a result of Compton cooling in the corona. Our work presents compelling observational evidence for the existence of slim accretion disks and elucidates the key parameters governing their behavior, paving the way for further exploration in this area.
AB - The properties of slim accretion disks, while crucial for our understanding of black hole growth, have yet to be studied extensively observationally. We analyze the multiepoch broadband spectral energy distribution of the changing-look active galactic nucleus 1ES 1927+654 to derive the properties of its complex, time-dependent accretion flow. The accretion rate decays as M ̇ ∝ t − 1.53 , consistent with the tidal disruption of a 1.1 M ⊙ star. Three components contribute to the spectral energy distribution: a central overheated zone resembling a slim disk, an outer truncated thin disk, and a hot corona. Photon trapping in the slim disk triggered by the high initial M ̇ was characterized by a low radiation efficiency (3%), which later more than doubled (8%) after M ̇ dropped sufficiently low for the disk to transition to a geometrically thin state. The blackbody temperature profile T ∝ R −0.60 for the inner overheated zone matches the theoretical expectations of a slim disk, while the effective temperature profile of T ∝ R −0.69 for the outer zone is consistent with the predictions of a thin disk. Both profiles flatten toward the inner boundary of the disk as a result of Compton cooling in the corona. Our work presents compelling observational evidence for the existence of slim accretion disks and elucidates the key parameters governing their behavior, paving the way for further exploration in this area.
UR - http://www.scopus.com/inward/record.url?scp=85208027069&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ad77a5
DO - 10.3847/1538-4357/ad77a5
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AN - SCOPUS:85208027069
SN - 0004-637X
VL - 975
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 50
ER -