Mon. Not. R. Astron. Soc., 492, 2858-2871 (2020/February-3)
Quasi-simultaneous radio and X-ray observations of Aql X-1 : probing low luminosities.
GUSINSKAIA N.V., HESSELS J.W.T., DEGENAAR N., DELLER A.T., MILLER-JONES J.C.A., ARCHIBALD A.M., HEINKE C.O., MOLDON J., PATRUNO A., TOMSICK J.A. and WIJNANDS R.
Abstract (from CDS):
Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio-X-ray luminosity correlation, LR ∝ LXβ, is not well constrained (β ≃ 0.4-0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1's 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies (6 x 1034 erg s–1 < LX <3 x 1035 erg s–1, i.e. the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1's radio emission decays more rapidly at low X-ray luminosities than previously assumed - at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data in the hard X-ray state, this can be modelled as a steep β =1.17+0.30–0.21 power-law index or as a sharp radio cut-off at LX <= 5 x 1035 erg s–1 (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies.
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
stars: neutron - X-rays: binaries
Status at CDS
Large table(s) will be appraised for possible ingestion in VizieR.
J1407+2807 is a probable misprint for J1407+2827. IGR J00291-5934 = IGR J00291+5934.
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