Modeling the hard states of three black hole candidates

TL;DR

This study applies an accretion-jet model to three black hole candidates in their hard states, successfully explaining their multiwavelength spectra and some timing features, thus supporting the model's broader applicability.

Contribution

It extends the accretion-jet model to three additional black hole candidates, demonstrating its effectiveness in explaining their spectral and timing properties.

Findings

Model explains radio to X-ray spectra well.

Qualitative explanation of timing features like QPOs.

Supports the accretion-jet model's applicability to multiple sources.

Abstract

Simultaneous multiwavelength observations were recently performed for three black hole candidates --- SWIFT J1753.5-0127, GRO J1655-40 and XTE J1720-318. In this paper we test the accretion-jet model originally proposed to XTE J1118+480 by investigating the hard state of these three sources using this model. The accretion flow in the model is composed of an inner hot accretion flow and an outer truncated thin disk. We find that the model satisfactorily explains the spectrum ranging from radio to X-rays, with the radio and X-ray spectra dominated by the synchrotron and thermal Comptonization emissions in the jet and the hot accretion flow respectively, while the infrared and optical being the sum of the emissions from the jet, hot accretion flow, and the truncated thin disk. Similar to the case of XTE J1118+480, the model can also explain, although only qualitatively in some cases, the observed timing features including QPO, and positive and negative time lags between the optical and X-ray emissions detected in SWIFT J1753.5-0127. The origin of the ejection events detected in XTE J1720-318 is also briefly discussed.