Evaluating the jet/accretion coupling of Aql X-1: probing the contribution of accretion flow spectral components
Abstract
The coupling between radio and X-ray luminosity is an important diagnostic tool to study the connection between the accretion inflow and jet outflow for low-mass X-ray binaries (LMXBs). The radio/X-ray correlation for individual neutron star (NS) LMXBs is scattered, whereas for individual black hole (BH) LMXBs a more consistent correlation is generally found. Furthermore, jet quenching is observed for both types of LMXBs, but it is unclear whether jets in NS-LMXBs quench as strongly as those in BH-LMXBs. While additional soft X-ray spectral components can be detected in NS-LMXB spectra due to the presence of the NS surface, disentangling the individual X-ray spectral components has thus far not been considered when studying the radio/X-ray coupling. Here we present eleven epochs of Swift/XRT observations matched with quasi-simultaneous archival radio observations of the 2009 November outburst of Aql X-1. We decompose the thermal and Comptonized spectral components in the Swift/XRT spectra, with the aim of studying whether the presence of additional thermal emission affects the coupling of the radio/X-ray luminosity. We find that there is no evidence of a significant thermal contribution in Swift/XRT spectra that could cause scatter in the radio/X-ray coupling. To explore the role of potential spectral degeneracies in the X-ray models and consider the improvements from including hard X-rays, we perform joint fits with quasi-simultaneous RXTE/PCA spectra. Follow-up research using more sensitive, broad-band X-ray observations and densely sampled near-simultaneous radio observations is required to study this in more detail.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2023
- DOI:
- 10.1093/mnras/stad548
- arXiv:
- arXiv:2204.10910
- Bibcode:
- 2023MNRAS.521.4490F
- Keywords:
-
- accretion;
- accretion discs;
- stars: neutron;
- X-rays: binaries;
- X-rays: individual (Aql X-1);
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 14 pages (12 main, 2 appendix), 12 figures, 4 tables. Accepted for publication in MNRAS