Bibcode
Armas Padilla, M.; Ponti, G.; De Marco, B.; Muñoz-Darias, T.; Haberl, F.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 3, p.3789-3795
Fecha de publicación:
1
2018
Número de citas
8
Número de citas referidas
8
Descripción
We report on a detailed study of the spectral and temporal properties of
the neutron star low-mass X-ray binary SLX 1737-282, which is located
only ∼1° away from Sgr A*. The system is expected to have a
short orbital period, even within the ultracompact regime, given its
persistent nature at low X-ray luminosities and the long duration
thermonuclear burst that it has displayed. We have analysed a Suzaku (18
ks) observation and an XMM-Newton (39 ks) observation taken 7 yr apart.
We infer (0.5-10 keV) X-ray luminosities in the range of 3-6 ×
1035ergs-1, in agreement with previous findings.
The spectra are well described by a relatively cool (kTbb =
0.5 keV) blackbody component plus a Comptonized emission component with
Γ ∼ 1.5-1.7. These values are consistent with the source being
in a faint hard state, as confirmed by the ∼20 per cent fractional
root-mean-square amplitude of the fast variability (0.1-7 Hz) inferred
from the XMM-Newton data. The electron temperature of the corona is
≳7 keV for the Suzaku observation, but it is measured to be as low
as ∼2 keV in the XMM-Newton data at higher flux. The latter is
significantly lower than expected for systems in the hard state. We
searched for X-ray pulsations and imposed an upper limit to their
semi-amplitude of 2 per cent (0.001-7 Hz). Finally, we investigated the
origin of the low-frequency variability emission present in the
XMM-Newton data and ruled out an absorption dip origin. This constraint
the orbital inclination of the system to ≲65° unless the
orbital period is longer than 11 h (i.e. the length of the XMM-Newton
observation).
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Montserrat
Armas Padilla