Comparison of giant radio pulses in young pulsars and millisecond pulsars

Pulse-to-pulse intensity variations are a common property of pulsar radio emission. For some of the objects single pulses are often 10-times stronger than their average pulse. The most dramatic events are so-called giant radio pulses (GRPs). They can be thousand times stronger than the regular single pulses from the pulsar. Giant pulses are a rare phenomenon, occurring in very few pulsars which split into two groups. The first group contains very young and energetic pulsars like the Crab pulsar, and its twin (PSR B0540-69) in the Large Magellanic Cloud (LMC), while the second group is represented by old, recycled millisecond pulsars like PSR B1937+21, PSR B1821-24, PSR B1957+20 and PSR J0218+4232 (the only millisecond pulsar detected in gamma-rays). We compare the characteristics of GRPs for these two pulsar groups. Moreover, our latest findings of new features in the Crab GRPs are presented. Analysis of our Effelsberg data at 8.35 GHz shows that GRPs do occur in all phases of its ordinary radio emission, including the phases of the two high frequency components (HFCs) visible only between 5 and 9 GHz.Comment: Proceedings of the 363. WE-Heraeus Seminar on: Neutron Stars and Pulsars (Posters and contributed talks) Physikzentrum Bad Honnef, Germany, May.14-19, 2006, eds. W.Becker, H.H.Huang, MPE Report 291, pp.64-6

Polarization characteristics of the Crab pulsar's giant radio pulses at HFCs phases

We discuss our recent discovery of the giant radio emission from the Crab pulsar at its high frequency components (HFCs) phases and show the polarization characteristic of these pulses. This leads us to a suggestion that there is no difference in the emission mechanism of the main pulse (MP), interpulse (IP) and HFCs. We briefly review the size distributions of the Crab giant radio pulses (GRPs) and discuss general characteristics of the GRP phenomenon in the Crab and other pulsars.Comment: AIP Conference Proceedings "Astrophysical Sources of High Energy Particles and Radiation", eds. T. Bulik et al. (NY:AIP), Volume 801, 2005, pp. 324-32

Spectrum management and compatibility studies with Python

We developed the pycraf Python package, which provides functions and procedures for various tasks related to spectrum-management compatibility studies. This includes an implementation of ITU-R Rec. P.452, which allows to calculate the path attenuation arising from the distance and terrain properties between an interferer and the victim service. A typical example would be the calculation of interference levels at a radio telescope produced from a radio broadcasting tower. Furthermore, pycraf provides functionality to calculate atmospheric attenuation as proposed in ITU-R Rec. P.676. Using the rich ecosystem of scientific Python libraries and our pycraf package, we performed a large number of compatibility studies. Here, we will highlight a recent case study, where we analysed the potential harm that the next-generation cell-phone standard 5G could bring to observations at a radio observatory. For this we implemented a Monte-Carlo simulation to deal with the quasi-statistical spatial distribution of base stations and user devices around the radio astronomy station.Comment: 17 pages, 21 figures, to appear in Advances in Radio Science, in pres

Flux-density spectral analysis for several pulsars and two newly-identified gigahertz-peaked spectra

In this paper we present results from flux density measurements for 21 pulsars over a wide frequency range, using the Giant Metrewave Radio Telescope (GMRT) and the Effelsberg telescope. Our sample was a set of mostly newly discovered pulsars from the selection of candidates for gigahertz-peaked spectra (GPS) pulsars. Using the results of our observations along with previously published data, we identify two new GPS pulsars. One of them, PSR J1740+1000, with dispersion measure of 24 pc cm$^{-3}$, is the first GPS pulsar with such a low DM value.We also selected several strong candidates for objects with high frequency turnover in their spectra which require further investigation.We also revisit our source selection criteria for future searches for GPS pulsars.Comment: 10 pages, 2 tables, 9 figures, accepted for publication in MNRA

Giant Radio Pulses from the Crab Pulsar

Individual giant radio pulses (GRPs) from the Crab pulsar last only a few microseconds. However, during that time they rank among the brightest objects in the radio sky reaching peak flux densities of up to 1500 Jy even at high radio frequencies. Our observations show that GRPs can be found in all phases of ordinary radio emission including the two high frequency components (HFCs) visible only between 5 and 9 GHz (Moffett & Hankins, 1996). This leads us to believe that there is no difference in the emission mechanism of the main pulse (MP), inter pulse (IP) and HFCs. High resolution dynamic spectra from our recent observations of giant pulses with the Effelsberg telescope at a center frequency of 8.35 GHz show distinct spectral maxima within our observational bandwidth of 500 MHz for individual pulses. Their narrow band components appear to be brighter at higher frequencies (8.6 GHz) than at lower ones (8.1 GHz). Moreover, there is an evidence for spectral evolution within and between those structures. High frequency features occur earlier than low frequency ones. Strong plasma turbulence might be a feasible mechanism for the creation of the high energy densities of ~6.7 x 10^4 erg cm^-3 and brightness temperatures of 10^31 K.Comment: accepted by Advances in Space Research, to appear in the 35th COSPAR assembly proceeding