arXiv subjects

Yuao Ma

Publications and source records attributed to Yuao Ma.

2 recordsLinked to original sources

arXiv2026

Is accretion flow magnetically arrested in M87?

It is still debating on whether the disc is magnetically arrested in M87. We assume that a weak external magnetic field is dragged inwards by the accretion disc, which is substantially enhanced to drive strong jets near the black hole horizon via Blandford-Znajek mechanism. The jet power of M87 has been well constrained with the observational data, while the accretion rate in the inner region of the accretion flow in M87 is estimated by fitting the multi-waveband continuum spectrum and the data of the Faraday rotation measurement, with which the surface density of the disc is derived. Our calculations show that, in order to produce the observed jet power $P_{\rm jet}=3.2\times 10^{43}~\rm erg~s^{-1}$, an external field with several hundred $μ\rm G$ at the outer edge of the disc is required to be amplified in the disc to hundreds G at the BH horizon, and the accretion flow in M87 must be magnetically arrested. A standard and normal evolution (SANE) disc is allowed in M87, only if the jet power is significantly lower than $\sim 1.75 \times 10^{43} \rm erg~ s^{-1}$,

astro-ph.HE↗

arXiv2026

Radio-X-ray Time Lags in GX 339-4: Probing Magnetic Field Transport in Black Hole Accretion

We present an analysis of the time delay between the radio emission and the X-ray Compton luminosity during the 2010-2011 outburst of GX 339-4. Using the interpolated cross-correlation function (ICCF), we measure the time delay between the Compton luminosity and the radio luminosity, and find that during the rising hard state, the radio emission precedes the Compton luminosity by approximately 3 days. In contrast, in the decaying hard state, the radio emission lags behind the Compton luminosity by about 8 days. By estimating the mass accretion rate and the disk truncation radius, the calculated inner magnetic field can account for both the radio delay in the decaying hard state and the radio precedence in the rising hard state. The time delays observed in different outbursts across multiple sources are compared further, and the underlying physical mechanisms account for this difference are discussed. These results provide insights into the evolving coupling between the inner accretion flow and the jet in black hole X-ray binaries.

astro-ph.HE↗