Swift confirm renewed activity of the transient neutron star X-ray binary Aql X-1
ATel #6286; A. Meshcheryakov (IKI; Moscow, Russia), S. Tsygankov (FINCA; Tuorla Observatory, Finland)
on 1 Jul 2014; 18:56 UT
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Subjects: X-ray, Neutron Star, Transient
Following the recent report of the brightening of the optical counterpart of the
transient neutron star X-ray binary Aql X-1 between June 28 and 29 (ATel #6280),
we observed the source with Swift on June 30 and July 01.
XRT instrument was operated mainly in the photon counting mode with total exposure
time 3.9 ks. The source is clearly seen in our observation. The X-ray
spectrum of the source can be described by an absorbed power-law model with
a hydrogen column density of N_H = (1.0 +/- 0.16)E22 cm-2 and a photon index
of 2.34 +/-0.18. The inferred 0.3-10 keV unabsorbed flux is
Fx=(1.23+/-0.32)E-10 erg/cm2/s, which translates into an isotropic
luminosity of Lx ~ 3.7E35 erg/s for a distance of 5 kpc. This is about two
orders of magnitude above the quiescent level of the source (~4e33erg/s).
The Swift observations confirm a renewed accretion activity in Aql X-1.
We thank Neil Gehrels and the Swift science team for making these
observations possible. Analysis of the XRT data was performed utilizing the
methods described by Evans et al. (2009, MNRAS, 397, 1177) and Evans et
al. (2007, A&A, 469, 379).
Further observations of Aql X-1 during accretion outburst in
X-ray,UV,Optical,IR and Radio bands are highly encouraged.