Are the relativistic Fe lines really relativistic Traineeship

Are the relativistic Fe lines really relativistic? Traineeship 2009 : A systematic analysis of the Fe K line from inner region of accretion disk of Neutron star LMXB with XMM-Newton Cherry Ng September 25 th 2009 1 Supervisors: • Maria Diaz-Trigo • Marion Cadolle • Simone Migliari

Outline 1. Objectives Fe K emission line Inner region of the accretion disk 2. Data analysis Importance of pile-up treatment 3. Results Relativistic Fe K line ? 4. Conclusion 2 Outline

Neutron Star Low-mass X-ray binaries (NS LMXB) Cackett et al (2008) Ap. J 674: 415 -420 Roche-lobe overflow Low-mass star Weakly magnetized NS Accretion disk • Fe K emission line • Typical energy : ~ 6. 5 ke. V 3 Objectives

Neutron Star Low-mass X-ray binaries (NS LMXB) • Systematic analysis • All publicly available bright Neutron Star LMXB • XMM-Newton 26 observations 17 sources 4 Objectives

Treatment of Pile-up No. of counts normalized to 1 Single & Double-px event pattern plot of Ser X 1 Comparison of Ser X 1 spectra before and after pile-up removal Single-px event Excess emission Double-px event Before pile-up removal After pile-up removal • Common problem of bright sources • 2 photons of lower energy read as 1 photon of higher energy • Distortion of spectra 5 Data analysis

Evolution of spectrum fit abs ( gaussian +diskbbody+bbodyrad + Fe K line ) +gaussian calib 1. 84 ke. V calib 2. 28 ke. V Emission 1 ke. V 6 Data analysis

Gaussian & Laor comparison on 4 U 1543 -62 Gaussian Laor Energy : Sigma : 0. 33± 0. 13 Laor index : 0. 97 Inclination : EW : Reduced X² : Rin: EW : Reduced X² : 32 ± 9 e. V 0. 96 • Narrow line width • Large inner radius • Similar X² • Insignificant evidence of asymmetric profile 7 Data analysis

Comparing results with published data Result from Cackett et al (2009) Result from my project 8 Results

Statistics on equivalent width Correlation between EW and n° of counts Correlation between EW and error • Broad line – result of bad statistics • Unlikely to be due to broadening mechanism of relativistic effect 9 Results

Conclusion • Relativistic origin for the broadening of Fe cannot be claimed • Further higher resolution spectroscopic data needed to place better constraints on possible contribution to the line emission from various parts of disk Thank you ! 10 Conclusion

Distribution of energy and sigma Distribution of energy of centroid of Fe line Distribution of sigma of Fe line

Background figure 35: Background spectrum for the pn camera during an observation with the filter wheel in the CLOSED position (top: single events, bottom: double events) in the energy range 0. 2 -18 ke. V. The prominent features around 1. 5 ke. V are Al-K, at 5. 5 ke. V Cr. K, at 8 ke. V Ni-K, Cu-K, Zn-K and at 17. 5 ke. V (only in doubles) Mo-K fluorescence lines. The rise of the spectrum below 0. 3 ke. V is due to the detector noise. The relative line strengths depend on the (variable) incident particle spectrum.