The size of accretion disks from self-consistent X-ray spectra and UV/optical/NIR photometry fitting: applications to ASASSN-14li and HLX-1

2024/08/30 by Muryel Guolo, Andrew Mummery, Guolo, Muryel +1 · 1 citation
Decision Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Particle Detector Development and Performance #Scientific Measurement and Uncertainty Evaluation

paper · pdf · doi:10.48550/arxiv.2408.17296

openalex publication_date 2024/08/30 · openalex created_date 2024/10/19 · openalex updated_date 2026/08/01

Abstract

We implement a standard thin disk model with the outer disk radius (R_{\rm out}) as a free parameter, integrating it into standard X-ray fitting package to enable self-consistent and simultaneous fitting of X-ray spectra and UV/optical/NIR photometry. We apply the model to the late-time data (Δt ≈ 350-1300 days) of the tidal disruption event (TDE) ASASSN-14li. We show that at these late-times the multi-wavelength emission of the source can be fully described by a bare compact accretion disk. We obtain a black hole mass (M_{\rm BH}) of 7⁺³_-2×10⁶ M_\odot, consistent with host-galaxy scaling relations; and an R_{\rm out} of 45 ± 13 R_{\rm g}, consistent with the circularization radius, with possible expansion at the latest epoch. We discuss how simplistic models, such as a single-temperature blackbody fitted to either X-ray spectra or UV/optical photometry, lead to erroneous interpretations on the scale/energetics of TDE emission. We also apply the model to the soft/high state of the intermediate-mass black hole (IMBH) candidate HLX-1. The model fits the full spectral energy distribution (from X-rays to NIR) without needing an additional stellar population component. We investigate how relativistic effects improve our results by implementing a version of the model with full ray tracing calculations in the Kerr metric. For HLX-1, we find M_{\rm BH} = 4⁺³_-1 × 10⁴ M_\odot and R_{\rm out} ≈ \rm few × 10³ R_{\rm g}, in agreement with previous findings. The relativistic model can constrain the inclination (i) of HLX-1 to be 10^o ≤ i ≤ 70^o.

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