Jet Forecast: Timing of Discrete Jet Ejections of Stellar-Mass Black Holes Anticipated via X-ray Properties
Abstract
The radio -- soft γ-ray data of the Galactic black hole binary XTE J1859+226 showed that discrete jets are launched when the inner radius of the accretion disk (Rin) rapidly approaches the innermost stable circular orbit (ISCO). Given the correlations among the X-ray fractional variability amplitude (rms), Rin, and the X-ray hardness, previous phenomenological findings related to jet ejections (``jet line'' and sharp drops of rms) also indicate that the rapid shrinkage of Rin down to the ISCO turns on the jet formation. In order to make clear how these properties appear in other objects, we investigated the X-ray and radio data of XTE J1550-564, GX 339-4, and MAXI J1820+070. We found that all the four sources show drops of Rin and rms 1-10 days ahead of a jet activity, and exhibit no huge jumps of the accretion rates prior to jet ejections. XTE J1859 and MAXI J1820 show the jet activities under sub-Eddington accretion. Models for the jet production that require an enhancement of Ṁ or a super-Eddington accretion rate are unlikely. Another behavior common to multiple sources is the curved shape of the rms--Rin correlation. Therefore, monitoring of Rin seems to be suitable to predict the timing of jet ejections. When both Rin and rms continuously decrease and when Rin is about to reach the ISCO, alerts can be circulated as a ``jet forecast'' for triggering Target-of-Opportunity observations.
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BibTeX
@misc{kawaguchi2026forecast,
title = {{Jet Forecast: Timing of Discrete Jet Ejections of Stellar-Mass Black Holes Anticipated via X-ray Properties}},
author = {Toshihiro Kawaguchi and Kazutaka Yamaoka},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.34947},
eprint = {2609.34947},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.34947},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Jet Forecast: Timing of Discrete Jet Ejections of Stellar-Mass Black Holes Anticipated via X-ray Properties
AU - Toshihiro Kawaguchi
AU - Kazutaka Yamaoka
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.34947
UR - https://arxiv.org/abs/2609.34947
AB - The radio -- soft γ-ray data of the Galactic black hole binary XTE J1859+226 showed that discrete jets are launched when the inner radius of the accretion disk (R_in) rapidly approaches the innermost stable circular orbit (ISCO). Given the correlations among the X-ray fractional variability amplitude (rms), R_in, and the X-ray hardness, previous phenomenological findings related to jet ejections (``jet line'' and sharp drops of rms) also indicate that the rapid shrinkage of R_in down to the ISCO turns on the jet formation. In order to make clear how these properties appear in other objects, we investigated the X-ray and radio data of XTE J1550-564, GX 339-4, and MAXI J1820+070. We found that all the four sources show drops of R_in and rms 1-10 days ahead of a jet activity, and exhibit no huge jumps of the accretion rates prior to jet ejections. XTE J1859 and MAXI J1820 show the jet activities under sub-Eddington accretion. Models for the jet production that require an enhancement of Ṁ or a super-Eddington accretion rate are unlikely. Another behavior common to multiple sources is the curved shape of the rms--R_in correlation. Therefore, monitoring of R_in seems to be suitable to predict the timing of jet ejections. When both R_in and rms continuously decrease and when R_in is about to reach the ISCO, alerts can be circulated as a ``jet forecast'' for triggering Target-of-Opportunity observations.
ER -