The delayed radio emission in the black hole X-ray binary MAXI J1348\(-\)630

• Published in: arXiv.org 2024-06
• Main Authors: You, Bei, Shuai-kang, Yang, Yan, Zhen, Cao, Xinwu, Zdziarski, Andrzej A
• Format: Article
• Language: English
• Subjects: Black holes; Correlation analysis; Coupling; Cross correlation; Energy bands; Luminosity; Outbursts; Radio emission; Radio observation; Time lag; Time measurement; X ray binaries; X ray stars; X-ray astronomy
• ISSN: 2331-8422

We explore the coupling between the accretion flow and the jet in black hole X-ray binary (BHXRB) MAXI J1348-630 by analyzing the X-ray and radio observations during its 2019 outburst. We measure the time delay between the radio and Comptonization fluxes with the interpolated cross-correlation function. For the first time, we find that the radio emission lags behind the X-ray Comptonization emission by about 3 days during the rising phase covering the rising hard state and the following soft state. Such a long radio delay indicates that the Comptonization emission most likely originates from the advection-dominated accretion flow rather than the jet in this source. The Comptonization luminosity \(L_{\rm C}\) in 0.1-100 keV and the radio luminosity \(L_{\rm R}\) at 5.5 GHz, after considering the radio delay of \(\sim 3\) days, follow the correlation with a slope \(\beta = 3.04 \pm 0.93\), which is much steeper than the previously reported \(\beta = 0.6\) or 1.40 using the total luminosity in the limited band (e.g., 1-10 keV) in the literature. This highlights the necessity of considering (1) the time delay, (2) the spectral decomposition, and (3) the broad energy band, in the radio-X-ray correlation analysis. As the jet reappears during the decaying phase (covering the soft state and the following decaying hard state) and the mini-outburst, the Componization and the radio emission appear to be almost simultaneous. And, the radio-Compton correlation during the mini-outburst becomes shallow with the correlation slope \(\beta = 1.11 \pm 0.15\). These indicate an intrinsic difference in the accretion-jet coupling physics between the main outburst and the mini-outburst.