Eight Years of Light from ASASSN-15oi: Toward Understanding the Late-time Evolution of TDEs

Abstract We present results from an extensive follow-up campaign of the tidal disruption event (TDE) ASASSN-15oi spanning δt ∼ 10–3000 days, offering an unprecedented window into the multiwavelength properties of a TDE during its first ≈8 yr of evolution. ASASSN-15oi is one of the few TDEs with strong detections at X-ray, optical/UV, and radio wavelengths and it also featured two delayed radio flares at δt ∼ 180 days and δt ∼ 1400 days. Our observations at δt > 1400 days reveal an absence of thermal X-rays, a late-time variability in the nonthermal X-ray emission, and sharp declines in the nonthermal X-ray and radio emission at δt ∼ 2800 days and ∼3000 days, respectively. The UV emission shows no significant evolution at δt > 400 days and remains above the pre-TDE level. We show that a cooling envelope model can explain the thermal emission consistently across all epochs. We also find that a scenario involving episodic ejection of material due to stream–stream collisions can possibly explain the first radio flare. Given the peculiar spectral and temporal evolution of the late-time emission, however, constraining the origins of the second radio flare and the nonthermal X-rays remains challenging. Our study underscores the critical role of long-term, multiwavelength follow-up to fully characterize the extended evolutionary phases of a TDE.

Authors

Institutions

Publication Details

Journal
The Astrophysical Journal
Published
2025-04-02
DOI
https://doi.org/10.3847/1538-4357/adb620
Citations
11
Primary Topic
Gamma-ray bursts and supernovae
Type
article
Field-Weighted Citation Impact
12.70
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Eight Years of Light from ASASSN-15oi: Toward Understanding the Late-time Evolution of TDEs

Y. Cendes, B. A. Zauderer, E. Ramírez-Ruiz, Collin T. Christy et al.
11 citations
The Astrophysical Journal
Gamma-ray bursts and supernovae
12.70
article

Eight Years of Light from ASASSN-15oi: Toward Understanding the Late-time Evolution of TDEs

Y. Cendes, B. A. Zauderer, E. Ramírez-Ruiz, Collin T. Christy, James K. Leung, T. Laskar, A. Horesh, P. K. Blanchard, E. Berger, Genevieve Schroeder, M. F. Bietenholz, Joe Bright, M. C. Stroh, A. Hajela, D. L. Coppejans, R. Chornock, G. Terreran, M. H. Wieringa, R. D. Saxton, Sebastián Gómez, S. Komossa, M. Nicholl, K. D. Alexander, R. Margutti, Huei Sears, Eli Wiston, N. Velez, A. J. Nayana, T. Eftekhari
article en
11 citations

Abstract

Abstract We present results from an extensive follow-up campaign of the tidal disruption event (TDE) ASASSN-15oi spanning δt ∼ 10–3000 days, offering an unprecedented window into the multiwavelength properties of a TDE during its first ≈8 yr of evolution. ASASSN-15oi is one of the few TDEs with strong detections at X-ray, optical/UV, and radio wavelengths and it also featured two delayed radio flares at δt ∼ 180 days and δt ∼ 1400 days. Our observations at δt > 1400 days reveal an absence of thermal X-rays, a late-time variability in the nonthermal X-ray emission, and sharp declines in the nonthermal X-ray and radio emission at δt ∼ 2800 days and ∼3000 days, respectively. The UV emission shows no significant evolution at δt > 400 days and remains above the pre-TDE level. We show that a cooling envelope model can explain the thermal emission consistently across all epochs. We also find that a scenario involving episodic ejection of material due to stream–stream collisions can possibly explain the first radio flare. Given the peculiar spectral and temporal evolution of the late-time emission, however, constraining the origins of the second radio flare and the nonthermal X-rays remains challenging. Our study underscores the critical role of long-term, multiwavelength follow-up to fully characterize the extended evolutionary phases of a TDE.

The Astrophysical JournalVol. 983(1)
Rutgers, The State University of New Jersey (US), Northwestern University (US), Queen's University Belfast (GB), Las Cumbres Observatory Global Telescope Network (US), Space Telescope Science Institute (US), Australia Telescope National Facility (AU), U.S. National Science Foundation (US), University of Arizona (US), Radboud University Nijmegen (NL), University of California, Santa Barbara (US), University of Oregon (US), University of California, Santa Cruz (US), University of Toronto (CA), Hebrew University of Jerusalem (IL), University of Utah (US), Nordic Institute of Asian Studies (DK), Hartebeesthoek Radio Astronomy Observatory (ZA), University of Warwick (GB), University of Oxford (GB), European Space Astronomy Centre (ES), Canadian Institute for Theoretical Astrophysics (CA), South African Radio Astronomy Observatory (ZA), Université Bourgogne Franche-Comté (FR), Center for Astrophysics Harvard & Smithsonian (US), Max Planck Institute for Radio Astronomy (DE), Ruhr University Bochum (DE), University of California, Berkeley (US)
Openalex Percentile: Top 1%
Gamma-ray bursts and supernovae
12.70
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.