Jet Forecast: Timing of Discrete Jet Ejections of Stellar-mass Black Holes Anticipated via X-Ray Properties
- 1University of Toyama
- 2Nagoya University
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 ( 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 in 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 in R in and rms 1–10 days ahead of a jet activity, and exhibit no huge jumps in 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 in M ̇ 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.
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BibTeX
@article{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},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/aeacc6},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeacc6},
note = {CC BY 4.0},
}
RIS
TY - JOUR
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 - 2026/11/05
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeacc6
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeacc6
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 in 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 in R in and rms 1–10 days ahead of a jet activity, and exhibit no huge jumps in 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 in M ̇ 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.
SN - 1538-4357
SN - 0004-637X
ER -