Studying the Spectral Energy Distributions Emanating from Regular Galactic XRBs

Abstract

X-ray binary systems (XRBs) exhibit similar dynamics and multimessenger emission mechanisms to active galactic nuclei (AGNs) with the benefit of shorter time scaling. Those systems produce rich spectral energy distributions (SEDs) ranging from the radio band to the very high energy gamma rays. The emission origin varies between the system’s accretion disk (X-rays) to the corona and, most notably, to the two twin plasma ejections (jets) that often meet the interstellar medium forming highly observable radio lobes. Modeling of the jets offers an excellent opportunity to understand the intrinsic mechanisms and the jet particles, such as electrons, positrons, and protons. In this work, we employ a lepto-hadronic jet model that assumes particle acceleration through shock waves over separate zonal regions of the jet. The hadronic models consider proton–proton collisions that end up in gamma-ray photons through neutral pion decays. The main leptonic mechanisms involve synchrotron radiation (from both electrons and protons) and inverse Compton scattering of ambient photons (coming from the disk, the corona, and the companion star) on jet electrons. The emissions from the disk, the corona, and the donor star are also included in the SED calculations, along with the photon absorption effects due to their interaction with higher-energy jet photons. We apply the model on a 10M⊙ black hole accreting at the Eddington rate out of a 20M⊙ companion star. One of our goals is to investigate and determine an optimal frame concerning the values for the free parameters that enter our calculations to produce higher integral fluxes.

Integral Fluxes of Neutrinos and Gamma-Rays Emitted from Neighboring X-ray Binaries

“…The dependence of the jet gamma-ray photon absorption on the disk's geometry and radiative efficiency is better illustrated in Refs. [39,40]. In those works, we conducted similar calculations which are, in the present work, extended by applications on two additional X-ray binaries, namely, GRO J1655-40 and LMC X-1.…”

“…In previous works, we assumed purely hadronic jets focusing on multiple independent acceleration zones [39], or we studied primarily the lepton-induced mechanisms investigating the dependence on the jet parameterization [40]. In both cases, priority was given only to the multi-wavelength photon emission from X-ray binary systems and not the production of neutrinos, which is included in this work.…”

“…It should be mentioned that the phenomenon of disk truncation during the spectral phase transition of the system is possible [50]. That would lead to a substantial decrease in photon absorption, as discussed in [40]. Nonetheless, for the time being, we adopt the conditions that allow maximum photon absorption in order to set minimum integral flux limits and thoroughly explore the impact of photon annihilation on the expected gammaray spectrum.…”

X-ray Spectroscopic Study of Low-Mass X-ray Binaries: A Review of Recent Progress via the Example of GX 339-4

“…According to the proposed mechanism [16], as the mass accretion rate increases, cold clumps can form within the hot accretion flow due to recondensation. Another component that is missing in this classical picture is the collimated jet [17], which can be a significant source of the X-ray emission in the hard state, and it is shown to dominate the X-ray emission in the quiescent state [18]. Recent studies showed that the jet contribution itself depends on the BH spin [19].…”