Abstract
We present preliminary results from a Chandra 30 ks observation of the atoll sourco 4U 1705 44. In particular we concentrate on the study of the iron Kα line, using the HEG spectrometer. The iron Kα line at ~ 6.6 keV is found to be intrinsically broad (FWHM ~ 1.7 keV); its width can be explained by reflection from a cold accretion disk extending down to ~ 17 km from the neutron star center or by Compton broadening in the hotter (~ 3 – 4 keV) corona.
Highlights
We present preliminary results from a Chan dra 30 ks observation of the atoll source 4U 1705—44
Broad emission lines (FWHM up to ~ 1 keV) at energies in the range 6.4 6.7 keV are often observed in the sp('ct,ra, of low-mass X-ray binaries hosting an old accreting neutron star
These features are powerful tools to investigate the structure of the accretion flow close to the central source; in particular, important information can be obtained from the detailed spec troscopy of t h(' iron K a emission line and absorption edge, since they are determined by the ionization state, geometry and velocity field of the reprocessing plasma. 4U 1705 44 is an atoll source which shows type-I X-ray bursts
Summary
We present preliminary results from a Chan dra 30 ks observation of the atoll source 4U 1705—44. Broad emission lines (FWHM up to ~ 1 keV) at energies in the range 6.4 6.7 keV are often observed in the sp('ct,ra, of low-mass X-ray binaries hosting an old accreting neutron star. These lines are identi fied with the Ko radiative transitions of iron at dif ferent ionization states. These features are powerful tools to investigate the structure of the accretion flow close to the central source; in particular, important information can be obtained from the detailed spec troscopy of t h(' iron K a emission line and absorption edge, since they are determined by the ionization state, geometry and velocity field of the reprocessing plasma.
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