A radio parallax to the black hole X-ray binary MAXI J1820+070

TL;DR

This study precisely measures the distance to the black hole binary MAXI J1820+070 using radio parallax, refining key system parameters and providing insights into its luminosity and jet properties.

Contribution

It presents the first model-independent radio parallax measurement for MAXI J1820+070, enabling accurate determination of its distance and related physical parameters.

Findings

Distance to MAXI J1820+070 is 2.96 ± 0.33 kpc.

Black hole mass is estimated at 9.2 ± 1.3 solar masses.

Jet inclination angle is approximately 63 degrees.

Abstract

Using the Very Long Baseline Array and the European Very Long Baseline Interferometry Network we have made a precise measurement of the radio parallax of the black hole X-ray binary MAXI\,J1820+070, providing a model-independent distance to the source. Our parallax measurement of ($0.348\pm0.033$) mas for MAXI J1820+070 translates to a distance of ($2.96\pm0.33$) kpc. This distance implies that the source reached ($15\pm3)\%$ of the Eddington luminosity at the peak of its outburst. Further, we use this distance to refine previous estimates of the jet inclination angle, jet velocity and the mass of the black hole in MAXI J1820+070 to be ($63\pm3)^{\circ}$, ($0.89\pm0.09)c$ and ($9.2\pm1.3) M_{\odot}$, respectively.