Bibcode
Tudose, V.; Fender, R. P.; Linares, M.; Maitra, D.; van der Klis, M.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 400, Issue 4, pp. 2111-2121.
Fecha de publicación:
12
2009
Número de citas
57
Número de citas referidas
49
Descripción
We study the accretion/ejection processes (i.e. disc/jet coupling) in
the neutron star X-ray binary Aquila X-1 via a multiwavelength approach.
We use in the radio band the publicly available Very Large Array archive
containing observations of the object between 1986 and 2005, in the
X-ray band the archival Rossi X-ray Timing Explorer data (Proportional
Counter Array and High Energy X-ray Timing Experiment) between 1997 and
2008, and in optical (R band) observations with the Small and Moderate
Aperture Research Telescope System recorded between 1998 and 2007. In
the combined data set, we find three outbursts for which
quasi-simultaneous radio, optical (R band) and X-ray data exist and
focus on them to some extent. We provide evidence that the disc/jet
coupling in Aquila X-1 is similar to what has been observed in black
hole X-ray binaries, at least from the point of view of the behaviour in
the hardness-intensity diagrams (the hysteresis effect included), when
the phenomenology of the jet is taken into account. Although based on a
very small number of observations, a radio/X-ray correlation seems to
exist for this system, with a slope of α = 0.40 +/- 0.07
(Fradio ~ FαX), which is
different than the slope of α = 1.40 +/- 0.25 found for another
atoll source, 4U 1728-34, but interestingly enough is relatively close
to the values obtained for several black hole X-ray binaries. No
significant correlation is found between the radio and optical (R-band)
emissions. We also report a significant drop in the radio flux from
Aquila X-1 above an X-ray flux of ~5 × 10-9 erg
cm-2 s-1. This behaviour, also reported in the
neutron star X-ray binary 4U 1728-34, may be analogous to the
suppression of radio emission in black hole X-ray binaries in bright,
soft X-ray states. It suggests that from this point of view neutron star
X-ray binaries can mimic the behaviour of black hole X-ray binaries in
suppressing the jet in soft/disc-dominated X-ray states.