2018A&A...616L..17S -
Astronomy and Astrophysics, volume 616, L17-17 (2018/8-1)
XMM-Newton detection of the 2.1 ms coherent pulsations from IGR J17379-3747.
SANNA A., BOZZO E., PAPITTO A., RIGGIO A., FERRIGNO C., DI SALVO T., IARIA R., MAZZOLA S.M., D'AMICO N. and BURDERI L.
Abstract (from CDS):
We report the detection of X-ray pulsations at 2.1ms from the known X-ray burster IGR J17379-3747 using XMM-Newton. The coherent signal shows a clear Doppler modulation from which we estimate an orbital period of ∼1.9h and a projected semi-major axis of ∼8lt-ms. Taking into account the lack of eclipses (inclination angle of <75°) and assuming a neutron star mass of 1.4M☉, we have estimated a minimum companion star of ∼0.06M☉. Considerations on the probability distribution of the binary inclination angle make the hypothesis of a main-sequence companion star less likely. On the other hand, the close correspondence with the orbital parameters of the accreting millisecond pulsar SAX J1808.4-3658 suggests the presence of a bloated brown dwarf. The energy spectrum of the source is well described by a soft disk black-body component (kT∼0.45keV) plus a Comptonisation spectrum with photon index ∼1.9. No sign of emission lines or reflection components are significantly detected. Finally, combining the source ephemerides estimated from the observed outbursts, we obtained a first constraint on the long-term orbital evolution of the order of Porb=(-2.5±2.3)x10–12s/s.
Abstract Copyright:
© ESO 2018
Journal keyword(s):
binaries: general - stars: neutron - X-rays: binaries - accretion, accretion disks
Simbad objects:
8
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