Karl-Heinz Kampert

CRPropa 2.0 -- a Public Framework for Propagating High Energy Nuclei, Secondary Gamma Rays and Neutrinos

Version 2.0 of CRPropa 1 is public software to model the extra-galactic propagation of ultra-high energy nuclei of atomic number Z 26 through structured magnetic fields and ambient photon backgrounds taking into account all relevant particle interactions. CRPropa covers the energy range 6 10 16 < E=eV < A 10 22 where A is the nuclear mass number. CRPropa can also be used to track secondary -rays and neutrinos which allows the study of their link with the charged primary nuclei ‐ the so called multi-messenger connection. After a general introduction we present several sample applications of current interest concerning the physics of extragalactic ultra-high energy radiation.

Radio galaxies of the local universe - All-sky catalog, luminosity functions, and clustering

To understand the feedback of black holes on their environment or the acceleration of ultra-high energy cosmic rays in the present cosmic epoch, a systematic, all-sky inventory of radio galaxies in the local universe is needed. Here we present the first catalog of radio-emitting galaxies that meets this requirement. Our catalog allows the selection of volume-limited subsamples containing all low-power radio galaxies, similar to the prototypical low-power radio galaxies Cen A or M87, within some hundred Mpc. It is constructed by matching radio emission from the NVSS and SUMSS surveys to galaxies of the 2MASS Redshift Survey (2MRS) using an image-level algorithm that properly treats the extended structure of radio sources. The sample contains 575 radio-emitting galaxies with a flux greater than 213 mJy at 1.4 GHz. Over 30% of the galaxies in our catalog are not contained in existing large-area extra-galactic radio samples. We compute the optical and radio luminosity functions and the fraction of radio galaxies as a function of galaxy luminosity. We find that the galaxy density around radio galaxies is significantly higher than around non-radio galaxies of the same luminosity and morphology. This enhanced clustering suggests a causal relation between external galaxy properties, such as environment or merger history, and the formation of powerful jets in the present universe. Since the enhancement is observed with respect to galaxies of the same luminosity and Hubble type, it is not primarily driven by black hole mass. Our automated matching procedure is found to select radio-emitting galaxies with high efficiency (99%) and purity (91%), which is key for future processing of deeper, larger samples.

CRPropa 3-a public astrophysical simulation framework for propagating extraterrestrial ultra-high energy particles

We present the simulation framework CRPropa version 3 designed for efficient development of astrophysical predictions for ultra-high energy particles. Users can assemble modules of the most relevant propagation effects in galactic and extragalactic space, include their own physics modules with new features, and receive on output primary and secondary cosmic messengers including nuclei, neutrinos and photons. In extension to the propagation physics contained in a previous CRPropa version, the new version facilitates high-performance computing and comprises new physical features such as an interface for galactic propagation using lensing techniques, an improved photonuclear interaction calculation, and propagation in time dependent environments to take into account cosmic evolution effects in anisotropy studies and variable sources. First applications using highlighted features are presented as well.

FPGA Based Signal-Processing for Radio Detection of Cosmic Rays

For the observation of ultra high-energy cosmic rays (UHECRs) by the detection of their coherent radio emission an FPGA based trigger and radio frequency interference (RFI) filter was developed. Using radio detection, the electromagnetic part of an air shower in the atmosphere may be studied in detail, thus providing information complementary to that obtained by water Cherenkov detectors which are predominantly sensitive to the muonic content of an air shower at ground. For an extensive radio detector array, due to the limited communication data rate, a sophisticated self trigger is necessary. However, radio signals in the frequency range of 30-80 MHz are significantly contaminated by RFI and human made distortions. The digitized signals are converted from the time to frequency domain by a FFT procedure, then a deconvolution and RFI-filters are applied to correct the frequency response and to suppress the RFI. Finally the filtered data is transformed back into the time domain by an iFFT, also generating an envelope as a base for the final self-trigger. To avoid leakage effect and to create an overlap of successive data blocks, trapezoidal windowing is applied with internal overclocking. The algorithms for two polarization channels have been successfully implemented in a single FPGA and tested in a prototype board with 180 MHz sampling rate, 16-bit dynamic range, and 12-bit resolution.

An FPGA based trigger and RFI filter for radio detection of cosmic rays

For the observation of UHECRs by the detection of their coherent radio emission an FPGA based trigger and RFI filter was developed. Using radio detection, the electromagnetic part of an air shower in the atmosphere may be studied in detail, thus providing information complementary to that obtained by water Cherenkov detectors which are predominantly sensitive to the muonic content of an air shower at ground. For an extensive radio detector array, due to the limited communication data rate, a sophisticated self trigger is necessary. However, radio signals in the frequency range of 30–80MHz are significantly contaminated by radio frequency interferences (RFI) and human made distortions. The digitized signals are converted from the time to frequency domain by a FFT procedure, then deconvolution and RFI-filters are applied to correct the frequency response and to suppress the RFI. Finally the filtered data is transformed back into the time domain by an iFFT, also generating an envelope as a base for the final self-trigger. To avoid leakage effects and to create an overlap of successive data blocks, trapezoidal windowing is applied with internal overclocking. The algorithms for two polarization channels have been successfully implemented in a single Altera® Cyclone III FPGA chip EP3C80F780C6 and tested in a prototype board with an 180 MHz sampling rate, 16 bit dynamic range, and 12-bit resolution.

A fast embedded system for radio detection of cosmic rays

For the detection of radio signals from ultra high energy (> 1017 eV) cosmic rays in the frequency range up to 80 MHz an embedded system was designed, built, and tested. A steep band-pass filter in the range of 30 to 80 MHz suppresses the main source of radio frequency interferences. To fulfill the data acquisition (DAQ) task, four 180 MHz twelve bit ADCs have to be read-out by a FPGA into a two gigabyte buffer memory. Furthermore the FPGA contains the trigger and a Altera NIOS II soft-core processor for data management. A GPS receiver controls the timing of the system. For the read-out an Ethernet-link and a CAN interface to a WLAN communication board is foreseen. The architecture of the system and the measured performance of the DAQ-board are described.