Evidence of mutually exclusive outflow forms from a black hole X-ray binary

TL;DR

This study demonstrates a clear anti-correlation between X-ray disk winds and radio jets in the BH XRB 4U 1630−472 across three soft-state–dominated outbursts, with winds dominating when jets are weak and vice versa, all at sub-Eddington luminosities consistent with a standard geometrically thin disk. Using NICER X-ray spectra and MeerKAT radio monitoring, the authors quantify wind properties with photoionized-absorber modeling (NH, $\log\xi$, velocity) and estimate mass outflow rates for winds ($\dot{M}_{\rm wind}\sim10^{17}$–$10^{18}$ g s$^{-1}$) and jets ($\dot{M}_{\rm jet}\sim10^{16}$–$10^{19}$ g s$^{-1}$) under reasonable geometrical assumptions. They find a robust anti-correlation between wind column density and radio jet strength (Spearman $\rho=-0.47$, significance $>97\%$), implying a mass-conservation–driven trade-off between outflow channels and suggesting a role for energy partitioning or magnetic-field configurations in regulating how accretion energy feeds winds or jets. The results provide new constraints on the physics of outflow launching in BH XRBs and motivate theoretical modeling of self-regulated feedback in accretion disks, with implications for understanding how stellar-mass black holes influence their environments. The work also highlights the value of coordinated, multi-wavelength campaigns to disentangle coupled accretion–outflow phenomena across states and luminosities.

Abstract

Accretion onto black holes often leads to the launch of outflows that significantly influence their surrounding environments. The two primary forms of these outflows are X-ray disk winds-hot, ionized gases ejected from the accretion disk-and relativistic jets, which are collimated streams of particles often expelled along the rotational axis of the black hole. While previous studies have revealed a general association between spectral states and different types of outflows, the physical mechanisms governing wind and jet formation remain debated. Here, using coordinated NICER and MeerKAT observations of the recurrent black hole X-ray binary 4U 1630-472, we identify a clear anti-correlation between X-ray disk winds and jets: during three recent outbursts, only one type of outflow is detected at a time. Notably, this apparent exclusivity occurs even as the overall accretion luminosity remains within the range expected for a standard thin disk, characteristic of the canonical soft state. These results suggest a competition between outflow channels that may depend on how the accretion energy is partitioned between the disk and the corona. Our findings provide new observational constraints on jet and wind formation in X-ray binaries and offer a fresh perspective on the interplay between different modes of accretion-driven feedback.

Figures (9)

• Figure 1: Supplementary Figure 0 $|$ NICER $2-10$ keV unfolded spectrum and the fitting residuals of the two observations mentioned in Figure 1. The fitting are conducted with the phenomenological model: tbabs $\times$ xscat $\times$ edge $\times$ (cflux $\times$ diskbb + cflux $\times$ nthcomp). The two observation have comparable flux and similar spectra, but the first observation (Obs ID: 6130010111) shows evidence of X-ray disk winds, the second observation (Obs ID: 4130010124) does not. Both spectrum and fitting residuals are shown with 1$\sigma$ errors.
• Figure 2: Supplementary Figure 1 $|$ Monitoring of the 2020, 2021 and 2022-2023 outbursts of 4U 1630$-$472. (a) The long term $2-20$ keV MAXI light curve. (b) The corresponding MAXI hardness, which is defined as the ratio between count rates in $4-10$ keV and $2-4$ keV bands. (c) The unabsorbed $1-10$ keV flux (in units of erg cm$^{-2}$ s; 3$\sigma$ errors) of the disk component (dark points) and the corona component (red points) for each NICER observation, which are extracted from the best-fit phenomenological model: tbabs $\times$ xscat $\times$ edge $\times$ (cflux $\times$ diskbb + cflux $\times$ nthcomp + gauss). (d) The MAXI hardness-intensity diagram, defined as the total $2-20$ keV count rate vs. the hardness ($4-10$ keV/$2-4$ keV). For panels (a), (b) and (d), the data point colors correspond to the time of the observation to facilitate comparison, and error bars represent 1$\sigma$ confidence intervals.
• Figure 3: Supplementary Figure 2 $|$ Multi-wavelength monitoring and radio--X-ray correlations for recent three outbursts. Left panels: MAXI/GSC (2–20 keV), Swift/BAT (15–50 keV), and MeerKAT (1.28 GHz) light curves, shown from top to bottom, respectively. Right: Correlations between the radio flux density and the simultaneous X-ray fluxes from Swift/BAT (green) and MAXI/GSC (black). For 2021 outburst, the grey point represent MAXI fluxes scaled from simultaneous NICER observations. Error bars indicate 1$\sigma$ confidence intervals, and 3$\sigma$ upper limits are shown for radio flux densities in cases of non-detection.
• Figure 4: Supplementary Figure 3 $|$ Multi-wavelength monitoring and radio--X-ray correlations for 2012 outburst. Left panels show MAXI/GSC (2–20 keV), Swift/BAT (15–50 keV), and ATCA (5.5 GHz) light curves, respectively. Right panel depicts correlation between the radio flux density and the simultaneous X-ray fluxes in Swift/BAT (green) and MAXI/GSC (black) energy bands. Error bars correspond to 1$\sigma$ confidence intervals.
• Figure 5: Supplementary Figure 4 $|$ Summary of the relations between disk fluxes $F_{\rm dbb}$, non-thermal fluxes $F_{\rm nth}$, radio flux densities, and disk wind column densities. Diamonds indicate observations with jets but no X-ray disk winds, while squares mark observations with X-ray disk winds but no jets. In both jet-active and wind-active states, the disk fluxes are comparable. Higher radio flux densities are generally associated with enhanced coronal emission. Error bars indicate 3$\sigma$ confidence intervals, with 3$\sigma$ upper limits shown for non-detections or unconstrained measurements.