Bibcode
Miller-Jones, J. C. A.; Sivakoff, G. R.; Altamirano, D.; Tudose, V.; Migliari, S.; Dhawan, V.; Fender, R. P.; Garrett, M. A.; Heinz, S.; Körding, E. G.; Krimm, H. A.; Linares, M.; Maitra, D.; Markoff, S.; Paragi, Z.; Remillard, R. A.; Rupen, M. P.; Rushton, A.; Russell, D. M.; Sarazin, C. L.; Spencer, R. E.
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 716, Issue 2, pp. L109-L114 (2010).
Fecha de publicación:
6
2010
Número de citas
68
Número de citas referidas
60
Descripción
The 2009 November outburst of the neutron star X-ray binary Aquila X-1
(Aql X-1) was observed with unprecedented radio coverage and
simultaneous pointed X-ray observations, tracing the radio emission
around the full X-ray hysteresis loop of the outburst for the first
time. We use these data to discuss the disk-jet coupling, finding the
radio emission to be consistent with being triggered at state
transitions, both from the hard to the soft spectral state and vice
versa. Our data appear to confirm previous suggestions of radio
quenching in the soft state above a threshold X-ray luminosity of ~10%
of the Eddington luminosity. We also present the first detections of Aql
X-1 with very long baseline interferometry, showing that any extended
emission is relatively diffuse and consistent with steady jets rather
than arising from discrete, compact knots. In all cases where
multi-frequency data were available, the source radio spectrum is
consistent with being flat or slightly inverted, suggesting that the
internal shock mechanism that is believed to produce optically thin
transient radio ejecta in black hole X-ray binaries is not active in Aql
X-1.