arXiv subjects

Fabian Kislat

Publications and source records attributed to Fabian Kislat.

76 records · Page 5Linked to original sources

arXiv2014

An Unfolding Method for X-ray Spectro-Polarimetry

X-ray polarimetry has great scientific potential and new experiments, such as X-Calibur, PoGOLite, XIPE, and GEMS, will not only be orders of magnitude more sensitive than previous missions, but also provide the capability to measure polarization over a wide energy range. However, the measured spectra depend on the collection area, detector responses, and, in case of balloon-borne experiments, the absorption of X-rays in the atmosphere, all of which are energy dependent. Combined with the typically steep source spectra, this leads to significant biases that need to be taken into account to correctly reconstruct energy-resolved polarization properties. In this paper, we present a method based on an iterative unfolding algorithm that makes it possible to simultaneously reconstruct the energy spectrum and the polarization properties as a function of true photon energy. We apply the method to a simulated X-Calibur data set and show that it is able to recover both the energy spectrum and the energy-dependent polarization fraction.

astro-ph.IM↗

arXiv2013

Tests of the Lorentz and CPT Symmetries at the Planck Energy Scale with X-Ray and Gamma-Ray Observations

X-ray and gamma-ray observations of astrophysical objects at cosmological distances can be used to probe the energy dependence of the speed of light with high accuracy and to search for violations of Lorentz invariance and CPT symmetry at the Planck energy scale. In this conference contribution, we discuss these searches in the theoretical framework of the Standard-Model Extension. We present new limits on the dispersion relation governed by operators of mass dimension d=5 and d=6, and we discuss avenues for future progress.

astro-ph.CO↗

arXiv2012

Optimization of the Design of the Hard X-ray Polarimeter X-Calibur

We report on the optimization of the hard X-ray polarimeter X-Calibur for a high-altitude balloon-flight in the focal plane of the InFOCμS X-ray telescope from Fort Sumner (NM) in Fall 2013. X-Calibur combines a low-Z scintillator slab to Compton-scatter photons with a high-Z Cadmium Zinc Telluride (CZT) detector assembly to photo-absorb the scattered photons. The detector makes use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation. X-Calibur achieves a high detection efficiency of order unity and reaches a sensitivity close to the best theoretically possible. In this paper, we discuss the optimization of the design of the instrument based on Monte Carlo simulations of polarized and unpolarized X-ray beams and of the most important background components. We calculate the sensitivity of the polarimeter for the upcoming balloon flight from Fort Sumner and for additional longer balloon flights with higher throughput mirrors. We conclude by emphasizing that Compton polarimeters on satellite borne missions can be used down to energies of a few keV.

astro-ph.IM↗

arXiv2012

Status of the IceTop air shower array at the South Pole

The IceTop air shower array is the surface component of the IceCube Neutrino Observatory at the geographic South Pole. The combination of IceTop and IceCube provides a new and powerful tool to measure cosmic ray composition in the energy range between about 300 TeV and 1 EeV by detecting the electromagnetic component at the surface in coincidence with the muon bundle in the deep underground detector. The paper will give an overview of the current status of the detector and the first physics results will be presented.

astro-ph.HE↗