12 research outputs found
Cyclotron lines in X-ray pulsars as a probe of relativistic plasmas in superstrong magnetic fields
The systematic search for the presence of cyclotron lines in the spectra of
accreting X-ray pulsars is being carried on with the BeppoSAX satellite since
the beginning of the mission. These highly successful observations allowed the
detection of cyclotron lines in many of the accreting X-ray pulsars observed.
Some correlations between the different measured parameters were found. We
present these correlations and discuss them in the framework of the current
theoretical scenario for the X-ray emission from these sources.Comment: 5 pages, 2 figures, uses aipproc.sty, to appear in Proceeding of
Fifth Compton Symposiu
The pulse phase-dependent spectrum of the anomalous X-ray pulsar 1RXS J170849-400910
We report on the results of a 50ks BeppoSAX observation of 1RXS
J170849-400910, one of the five (plus a candidate) known anomalous X-ray
pulsars. The BeppoSAX data are consistent with a power-law plus blackbody
spectral decomposition, making 1RXS J170849-400910 the fourth source of this
class for which such a spectral decomposition was found. The inferred power-law
slope and blackbody temperature are Gamma~2.6 and kT_BB~0.46keV, respectively.
We found significant energy-dependence of the pulse profile, a remarkable
feature for an AXP. By using the power-law plus blackbody decomposition we
detected a significant variation in at least one spectral parameter, the
power-law photon index, as a function of the pulse phase. This is the first
significant detection of spectral parameter variation in an AXP. The
implications of these results are briefly discussed.Comment: 5 pages. Accepted for publication on ApJ Letters. emulateapj5.sty
macro use
Evidence of a cyclotron feature in the spectrum of the anomalous X-ray pulsar 1RXS J170849-400910
We report the results of a long observation of the anomalous X-ray pulsar
1RXS J170849-400910 obtained with the BeppoSAX satellite in August 2001. The
best-fit phase-averaged spectrum was an absorbed power law plus blackbody
model, with photon index Gamma~2.4 and a blackbody temperature of kT_bb~0.4
keV. We confirm the presence of significant spectral variations with the
rotational phase of the pulsar. In the spectrum corresponding to the rising
part of the pulse we found an absorption-like feature at ~8.1 keV (a
significance of 4 sigma), most likely due to cyclotron resonant scattering. The
centroid energy converts to a magnetic field of 9x10^11 G and 1.6x10^15 G in
the case of electrons and protons, respectively. If confirmed, this would be
the first detection of a cyclotron feature in the spectrum of an anomalous
X-ray pulsar.Comment: 5 pages, 5 figures. Accepted for publication on ApJ Letter
Silicon pore optics mirror modules for inner and outer radii
Athena (Advanced Telescope for High Energy Astrophysics) is an x-ray observatory using a Silicon Pore Optics telescope and was selected as ESA's second L-class science mission for a launch in 2028. The x-ray telescope consists of several hundreds of mirror modules distributed over about 15-20 radial rings. The radius of curvature and the module sizes vary among the different radial positions of the rings resulting in different technical challenges for mirror modules for inner and outer radii. We present first results of demonstrating Silicon Pore Optics for the extreme radial positions of the Athena telescope. For the inner most radii (0.25 m) a new mirror plate design is shown which overcomes the challenges of larger curvatures, higher stress values and bigger plates. Preliminary designs for the mounting system and its mechanical properties are discussed for mirror modules covering all other radial positions up to the most outer radius of the Athena telescope