New Insights into Accretion Disk Sizes from X-ray and Photometric Data
Recent research by Muryel Guolo and Andrew Mummery focuses on the size of accretion disks using self-consistent X-ray spectra combined with UV, optical, and near-infrared photometry. The study, titled "The size of accretion disks from self-consistent X-ray spectra + UV/optical/NIR photometry fitting: applications to ASASSN-14li and HLX-1," was submitted to the Astrophysical Journal on August 30, 2024.
The researchers implemented a standard thin disk model, allowing for the outer disk radius to be a free parameter. This model was integrated into a standard X-ray fitting package to enable simultaneous fitting of X-ray spectra and multi-wavelength photometry. The findings were applied to the late-time data of the tidal disruption event ASASSN-14li, which occurred approximately 350 to 1300 days prior to the analysis.
The results indicate that the multi-wavelength emission from ASASSN-14li can be described by a bare compact accretion disk. The study estimates a black hole mass of approximately 7 million solar masses and an outer disk radius of about 45 gravitational radii, which aligns with the expected circularization radius. The researchers caution that simpler models, such as single-temperature blackbody fits, may lead to incorrect interpretations regarding the scale and energetics of tidal disruption event emissions.
Additionally, the model was applied to HLX-1, an intermediate-mass black hole candidate. The findings suggest that the spectral energy distribution from X-rays to near-infrared can be accurately modeled without the need for an additional stellar population component. The study also explored how relativistic effects can enhance the results, providing constraints on the inclination of HLX-1 between 20 and 70 degrees.
This research contributes to a deeper understanding of accretion processes and the characteristics of black holes, which are critical for astrophysical studies. The complete findings can be accessed through the arXiv repository under the identifier arXiv:2408.17296.