Improved analysis of time delays between radio wavelengths and X-ray of Sgr A* flares in the shock oscillation model
Abstract
We present an improved analysis of the time delays between radio and X-ray flares from the supermassive black hole Sagittarius A* (Sgr A*), extending our previous shock oscillation model by incorporating Compton scattering. Our simulations predict delay times of 1-4 h between X-ray and radio flares, 20-40 min and 0.5-1 h between 334 GHz and 4.5 μm and 2-8 keV flares, and 7-20 min and 0.5-1 h between 22-43 GHz and 350 GHz radio flares, respectively, in good agreement with recent observations. The delay time between the radio emissions (synchrotron) and X-ray emissions (bremsstrahlung) is interpreted as the transit time for sound waves traveling from the central core near the event horizon to the location of the oscillating shock. Additionally, the delay time observed between different radio wavelengths corresponds to the transit time of sound waves moving between the frequency-dependent effective radii Reff(ν), where the optical thickness τν(R) at frequency ν equals one on the surface of the accretion disc. The X-ray emission and the radio emission at lower frequencies peak later than the radio emission at higher frequencies. This delay occurs because the acoustic perturbations created by synchrotron emission peak near the event horizon and then expand outward. Conversely, an inverse delay happens when the acoustic waves generated by the upstream shock wave travel toward the event horizon. The predicted delay times from this interpretation qualitatively match the numerical results obtained in simulations.
Related
- An Evolving Leptonic Jet Model for Delayed Radio Flares in Neutrino Blazars
- The Association of Solar Radio Bursts with Eruptive and Confined Flares
- Type I Solar Radio Bursts Modulated by Solar Flares
- Fast Radio Bursts from Monster Shocks and Flares of Inspiraling Binary Neutron Stars: A Kinetic Model for Double Pulsar
- Type III radio bursts associated with jets in two solar flares
BibTeX
@misc{aktar2026improved,
title = {{Improved analysis of time delays between radio wavelengths and X-ray of Sgr A* flares in the shock oscillation model}},
author = {Ramiz Aktar and Toru Okuda and Chandra B. Singh},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11127},
eprint = {2610.11127},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11127},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Improved analysis of time delays between radio wavelengths and X-ray of Sgr A* flares in the shock oscillation model
AU - Ramiz Aktar
AU - Toru Okuda
AU - Chandra B. Singh
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.11127
UR - https://arxiv.org/abs/2610.11127
AB - We present an improved analysis of the time delays between radio and X-ray flares from the supermassive black hole Sagittarius A* (Sgr A*), extending our previous shock oscillation model by incorporating Compton scattering. Our simulations predict delay times of 1-4 h between X-ray and radio flares, 20-40 min and 0.5-1 h between 334 GHz and 4.5 μm and 2-8 keV flares, and 7-20 min and 0.5-1 h between 22-43 GHz and 350 GHz radio flares, respectively, in good agreement with recent observations. The delay time between the radio emissions (synchrotron) and X-ray emissions (bremsstrahlung) is interpreted as the transit time for sound waves traveling from the central core near the event horizon to the location of the oscillating shock. Additionally, the delay time observed between different radio wavelengths corresponds to the transit time of sound waves moving between the frequency-dependent effective radii R_eff(ν), where the optical thickness τ_ν(R) at frequency ν equals one on the surface of the accretion disc. The X-ray emission and the radio emission at lower frequencies peak later than the radio emission at higher frequencies. This delay occurs because the acoustic perturbations created by synchrotron emission peak near the event horizon and then expand outward. Conversely, an inverse delay happens when the acoustic waves generated by the upstream shock wave travel toward the event horizon. The predicted delay times from this interpretation qualitatively match the numerical results obtained in simulations.
ER -