Spectral Energy Distributions of Southern Binary X-Ray Sources

TL;DR

This study monitors 48 X-ray binaries across multiple wavelengths to construct spectral energy distributions, revealing class-specific emission behaviors and providing constraints for theoretical models of these sources.

Contribution

It presents the first comprehensive multi-wavelength spectral energy distributions for a large sample of X-ray binaries, covering all major classes and states.

Findings

Radio emission detected from Z sources in specific states.

No significant radio emission from pulsars or atoll sources.

Observations support existing models of source behavior.

Abstract

The rapid variability of X-ray binaries produces a wide range of X-ray states that are linked to activity across the electromagnetic spectrum. It is particularly challenging to study a sample of sources large enough to include all types in their various states, and to cover the full range of frequencies that show flux density variations. Simultaneous observations with many telescopes are necessary. In this project we monitor 48 X-ray binaries with seven telescopes across the electromagnetic spectrum from 5 x 10^9 Hz to 10^19 Hz, including ground-based radio, IR, and optical observatories and five instruments on two spacecraft over a one-week period. We construct spectral energy distributions and matching X-ray color-intensity diagrams for 20 sources that have the most extensive detections. Our observations are consistent with several models of expected behavior proposed for the different classes: we detect no significant radio emission from pulsars or atoll sources, but we do detect radio emission from Z sources in the normal or horizontal branch, and from black holes in the high/soft, low/hard and quiescent states. The survey data provide useful constraints for more detailed models predicting behavior from the different classes of sources.