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Title: Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li

Abstract

We carried out the first multi-wavelength (optical/UV and X-ray) photometric reverberation mapping of a tidal disruption flare (TDF) ASASSN-14li. We find that its X-ray variations are correlated with and lag the optical/UV fluctuations by 32 ± 4 days. Based on the direction and the magnitude of the X-ray time lag, we rule out X-ray reprocessing and direct emission from a standard circular thin disk as the dominant source of its optical/UV emission. The lag magnitude also rules out an AGN disk-driven instability as the origin of ASASSN-14li and thus strongly supports the tidal disruption picture for this event and similar objects. We suggest that the majority of the optical/UV emission likely originates from debris stream self-interactions. Perturbations at the self-interaction sites produce optical/UV variability and travel down to the black hole where they modulate the X-rays. The time lag between the optical/UV and the X-rays variations thus correspond to the time taken by these fluctuations to travel from the self-interaction site to close to the black hole. We further discuss these time lags within the context of the three variants of the self-interaction model. High-cadence monitoring observations of future TDFs will be sensitive enough to detect these echoes and wouldmore » allow us to establish the origin of optical/UV emission in TDFs in general.« less

Authors:
;  [1]; ;  [2];  [3];  [4];  [5]
  1. Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  2. NASA’s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  4. Columbia University, New York, NY 10027 (United States)
  5. The Johns Hopkins University, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22654515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 837; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; DISTURBANCES; EMISSION; FLUCTUATIONS; INSTABILITY; INTERACTIONS; PERTURBATION THEORY; REPROCESSING; STREAMS; WAVELENGTHS; X RADIATION

Citation Formats

Pasham, Dheeraj R., Sadowski, Aleksander, Cenko, S. Bradley, Cannizzo, John K., Guillochon, James, Stone, Nicholas C., and Velzen, Sjoert van. Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA6003.
Pasham, Dheeraj R., Sadowski, Aleksander, Cenko, S. Bradley, Cannizzo, John K., Guillochon, James, Stone, Nicholas C., & Velzen, Sjoert van. Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li. United States. doi:10.3847/2041-8213/AA6003.
Pasham, Dheeraj R., Sadowski, Aleksander, Cenko, S. Bradley, Cannizzo, John K., Guillochon, James, Stone, Nicholas C., and Velzen, Sjoert van. Fri . "Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li". United States. doi:10.3847/2041-8213/AA6003.
@article{osti_22654515,
title = {Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li},
author = {Pasham, Dheeraj R. and Sadowski, Aleksander and Cenko, S. Bradley and Cannizzo, John K. and Guillochon, James and Stone, Nicholas C. and Velzen, Sjoert van},
abstractNote = {We carried out the first multi-wavelength (optical/UV and X-ray) photometric reverberation mapping of a tidal disruption flare (TDF) ASASSN-14li. We find that its X-ray variations are correlated with and lag the optical/UV fluctuations by 32 ± 4 days. Based on the direction and the magnitude of the X-ray time lag, we rule out X-ray reprocessing and direct emission from a standard circular thin disk as the dominant source of its optical/UV emission. The lag magnitude also rules out an AGN disk-driven instability as the origin of ASASSN-14li and thus strongly supports the tidal disruption picture for this event and similar objects. We suggest that the majority of the optical/UV emission likely originates from debris stream self-interactions. Perturbations at the self-interaction sites produce optical/UV variability and travel down to the black hole where they modulate the X-rays. The time lag between the optical/UV and the X-rays variations thus correspond to the time taken by these fluctuations to travel from the self-interaction site to close to the black hole. We further discuss these time lags within the context of the three variants of the self-interaction model. High-cadence monitoring observations of future TDFs will be sensitive enough to detect these echoes and would allow us to establish the origin of optical/UV emission in TDFs in general.},
doi = {10.3847/2041-8213/AA6003},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 837,
place = {United States},
year = {Fri Mar 10 00:00:00 EST 2017},
month = {Fri Mar 10 00:00:00 EST 2017}
}