4 research outputs found
Performance Testing of a Large-Format Reflection Grating Prototype for a Suborbital Rocket Payload
The soft X-ray grating spectrometer on board the Off-plane Grating Rocket
Experiment (OGRE) hopes to achieve the highest resolution soft X-ray spectrum
of an astrophysical object when it is launched via suborbital rocket. Paramount
to the success of the spectrometer are the performance of the reflection
gratings populating its reflection grating assembly. To test current grating
fabrication capabilities, a grating prototype for the payload was fabricated
via electron-beam lithography at The Pennsylvania State University's Materials
Research Institute and was subsequently tested for performance at Max Planck
Institute for Extraterrestrial Physics' PANTER X-ray Test Facility. Bayesian
modeling of the resulting data via Markov chain Monte Carlo (MCMC) sampling
indicated that the grating achieved the OGRE single-grating resolution
requirement of at the 94% confidence level.
The resulting posterior probability distribution suggests that this
confidence level is likely a conservative estimate though, since only a finite
parameter space was sampled and the model could not constrain the upper
bound of to less than infinity. Raytrace simulations of the system found
that the observed data can be reproduced with a grating performing at
. It is therefore postulated that the behavior of the obtained
posterior probability distribution can be explained by a finite
measurement limit of the system and not a finite limit on . Implications
of these results and improvements to the test setup are discussed.Comment: 25 pages, 16 figures, preprint of an article accepted for publication
in the Journal of Astronomical Instrumentation \copyright 2020 [copyright
World Scientific Publishing Company]
[https://www.worldscientific.com/worldscinet/jai
Calibration of X-ray telescope prototypes at PANTER
We report a ground X-ray calibration of two X-ray telescope prototypes at the
PANTER X-ray Test Facility, of the Max-Planck-Institute for Extraterrestrial
Physics, in Neuried, Germany. The X-ray telescope prototypes were developed by
the Institute of Precision Optical Engineering (IPOE) of Tongji University, in
a conical Wolter-I configuration, using thermal glass slumping technology.
Prototype #1 with 3 layers and Prototype #2 with 21 layers were tested to
assess the prototypes' on-axis imaging performance. The measurement of
Prototype #1 indicates a Half Power Diameter (HPD) of 82" at 1.49 keV. As for
Prototype #2, we performed more comprehensive measurements of on-axis angular
resolution and effective area at several energies ranging from 0.5-10 keV. The
HPD and effective area are 111" and 39 cm^2 at 1.49 keV, respectively, at which
energy the on-axis performance of the prototypes is our greatest concern.Comment: 11 pages, 9 figure
X-ray analysis of local mid-infrared selected Compton-thick AGN candidates
Cosmic X-ray background synthesis models (Gilli 2007) require a significant fraction of obscured AGN, some of which are expected to be heavily obscured (Compton-thick), but the number density of observationally found obscured sources is still an open issue (Vignali 2010, 2014). This thesis work takes advantage of recent NuSTAR data and is based on a multiwavelength research approach. Gruppioni et al. 2016 compared the AGN bolometric luminosity, for a sample of local 12 micron Seyfert galaxies, derived from the SED decomposition to the same quantity obtained by the 2-10 keV luminosity (IPAC-NED). A difference up to two orders of magnitude resulted between these quantities for some sources. Thus, the intrinsic X-ray luminosity obtained correcting for the obscuration may be underestimated. In this thesis we have tested this hypothesis by re-analysing the X-ray spectra of three of the sources (UGC05101, NGC1194 and NGC3079), for which observations from NuSTAR and Chandra and/or XMM-Newton were available. This is meant to extend our analysis to energies above 10 keV and thus estimate the AGN column density as reliable as possible. For spectral fitting we made use of both the commonly used XSPEC package and the two very recent MYtorus and BNtorus physical models. The available wide bandpass allowed us to achieve new and more solid insights into the X-ray spectral properties of these sources. The measured absorption column densities are highly suggestive of heavy obscuration. Once corrected the X-ray AGN luminosity for the obscuration estimated through our spectral analysis, we compared the L(X) values in the 2-10 keV band with those derived from the MIR band, by means of the relation by Gandhi, 2009. As expected, the values derived from this relation are in good agreement with those we measured, indicating that the column densities were underestimated in the previous literature works