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Discovery of ABSORPTION LINES in Low Mass X-ray Binaries: MXB 1659-298 and GX13+1

L. Sidoli (IASF, Milano) A.N. Parmar T. Oosterbroek D. Lumb & C. Erd (ESA/ESTEC, Noordwijk,The Netherlands). Discovery of ABSORPTION LINES in Low Mass X-ray Binaries: MXB 1659-298 and GX13+1. Private data (PI: A.N. Parmar) observation performed in 2001 Feb.

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Discovery of ABSORPTION LINES in Low Mass X-ray Binaries: MXB 1659-298 and GX13+1

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  1. L. Sidoli (IASF, Milano) A.N. Parmar T. Oosterbroek D. Lumb & C. Erd (ESA/ESTEC, Noordwijk,The Netherlands) Discovery of ABSORPTION LINES in Low Mass X-ray Binaries: MXB 1659-298 and GX13+1

  2. Private data (PI: A.N. Parmar) observation performed in 2001 Feb. PV data (3 observations) Rev. 56 & 57 observations performed in Mar.-Apr. 2000 Summary of the XMM observations • MXB 1659-298 (Sidoli et al. 2001, A&A 379, 540) • GX 13+1 (Sidoli et al. 2002, A&A 385, 940)

  3. Two Low Mass X-ray Binaries

  4. GX 13+1 • Bright and persistent LMXB • Radio & infrared counterparts • It displays a 15% modulation with a period of ~25 days, probably orbital (but not confirmed yet) • @ ~ 7 kpc distance • Absorption Fe lines discovered with ASCA (Ueda et al. 2001)

  5. MXB 1659-298 EPIC lightcurve

  6. MXB1659-298 Persistent Spectrum • L (2-10 keV) = 1.6E37 erg/s (@ 15 kpc) • Column Density ~ 0.35 E22 cm-2 • Fe emission line ~ 6.5 keV (EW ~ 160 eV) • Fe absorption lines: • Fe xxv E=6.64 keV, EW= 33 eV • Fe xxvi E=6.9 keV, EW = 42 eV

  7. Fe XXV Fe XXVI MXB 1659-298

  8. Orbital Dependence of the IRON Absorption Lines MXB 1659-298

  9. MXB1659-298 RGS Spectrum

  10. MXB1659-298 RGS Spectrum

  11. GX13+1 XMM-Newton Observation • 3 on-axis PV observations • MOS full frame, pile-up problems • PN Timing Mode data have been considered • Exposure Times = 2.5 ks (obs.0101), 2.1 ks (obs. 0901), 2.3 ks (obs. 1001) • Continuum modeled with the ASCA model (Ueda et al. 2001): absorbed BBody + diskBB

  12. GX13+1 PN Spectrum

  13. GX13+1 PN Spectrum

  14. Summary of the GX13+1 features • Absorption line @ 4.1 keV (EW~7 eV) likely due to CaXX • Absorption lines @ 6.7 & 7 keV (EWs ~ 20 & 50 eV respectively) produced by Fe XXV Kalpha and Fe XXVI Kalpha absorption • Absorption lines @ 7.8 & 8.3 keV (EW ~ 30 & 40 eV respectively), probably due to Fe XXV Kbeta and Fe XXVI Kbeta absorption • Fe xxv edge @ 8.83 keV • Fe xxvi edge @ 9.28 keV • Fe broad emission line @ 6.3 keV

  15. CONCLUSIONS • MXB 1659-298: • Ovii, Ne X, Fe XXV, Fe XXVI narrow absorption lines mean highly ionized plasma & anisotropy • No orbital dependence • Absorption in persistent spectrum implies absorption NOT due to the same matter producing absorption DIPS • Flattened geometry of the absorbing matter above the accretion disk, around the central source

  16. CONCLUSIONS 2 • GX13+1: • Orbital period is not known yet, so the orbital dependence cannot be studied. In any case, if 25 days is the real orbital period, the XMM obs. cover only a fraction of it • No evidence for any velocity shifts in the line centroids • Narrow lines • The EWs of the Fe Kalpha lines are consistent with those measured with ASCA few years before. This means a STABLE GEOMETRYof the ABSORBING PLASMA

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