Are the relativistic Fe lines really relativistic? 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 Supervisors: Maria Diaz-Trigo Marion Cadolle Simone Migliari 1 Traineeship 2009 :

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

Weakly magnetized NS Accretion disk Roche-lobe overflow Low-mass star Fe K emission line Typical energy : ~ 6.5 keV Cackett et al (2008) ApJ 674: Objectives 3 Neutron Star Low-mass X-ray binaries (NS LMXB)‏

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

No. of counts normalized to 1 Comparison of Ser X1 spectra before and after pile-up removalSingle & Double-px event pattern plot of Ser X1 Common problem of bright sources 2 photons of lower energy read as 1 photon of higher energy Distortion of spectra Single-px event Double-px event Before pile-up removal Excess emission 5 Treatment of Pile-up Data analysis

( + + ) + gaussiandiskbbody+bbodyradFe K linegaussian+gaussian Emission 1keV calib 1.84keV calib 2.28keV abs 6 Evolution of spectrum fit Data analysis

Energy : Laor index : Rin: Inclination : EW : 32 ± 9 eV Reduced X² : 0.96 Energy : Sigma : 0.33±0.13 EW : Reduced X² : Gaussian & Laor comparison on 4U GaussianLaor Narrow line width Large inner radius Similar X² Insignificant evidence of asymmetric profile Data analysis

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

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

10 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 Conclusion Thank you ! Thank you !

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

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 keV. The prominent features around 1.5 keV are Al-K, at 5.5 keV Cr- K, at 8 keV Ni-K, Cu-K, Zn-K and at 17.5 keV (only in doubles) Mo-K fluorescence lines. The rise of the spectrum below 0.3 keV is due to the detector noise. The relative line strengths depend on the (variable) incident particle spectrum.