Three-dimensional Nanosecond Radio Imaging of Cosmic Rays and Other Things

Contains fulltext : 72444.pdf (publisher's version ) (Closed access)Frontiers of Astrophysics: A Celebration of NRAO's 50th Anniversary,, 18 juni 200

Lofar und die Epoche der Reionisation

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LOFAR- The Low Frequency Array

LOFAR is an innovative radio telescope in the frequency range of 10-240 MHz, realized as a phased array. It will become the largest radio telescope in the world in the time frame 2006-2010, located in Northern Europe. LOFAR is being implemented as a Wide Area Sensor Network which connects thousands of cheap sensors spread throughout the country to a central super computer using an ultra-broadband, synchronized data network. As the central processor IBM has provided its Blue Gene/L supercomputer. It will process streaming data with about 0.5 Terabit per second. Many simple radio antennas connected to the network turn it into a huge radio telescope for cosmological studies. In addition, geophones will turn LOFAR into an earthquake monitoring system and infrasound and meteorology sensors will turn LOFAR into a real-time weather monitoring array for agricultural applications. LOFAR is the first radio telescopes that can listen to radio signals from the entire sky overhead, on all time scales, at a large range of frequencies, and even look back in time for a couple of seconds. The main strength of LOFAR are surveys. One goal is to detect the first generation of black holes and galaxies in the universe during the epoch of reionization and study hydrogen formed after the big bang. LOFAR is also an ideal system to discover transient and sporadic radio signals. Likely transient sources to be discovered with LOFAR are bursting stars and Jupiter-like planets, gamma-ray bursts, radio outbursts from black holes, but also lightning on Earth and even radio flashes from ultra-high energy cosmic particles hitting the Earth atmosphere. Some LOFAR prototypes have recently been built. They have produced the first instantaneous all-sky maps and discovered the radio emission from cosmic particle air showers

Vliegende sterrenstelsels

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LOFAR- The Low Frequency Array

Item does not contain fulltextLOFAR is an innovative radio telescope in the frequency range of 10-240 MHz, realized as a phased array. It will become the largest radio telescope in the world in the time frame 2006-2010, located in Northern Europe. LOFAR is being implemented as a Wide Area Sensor Network which connects thousands of cheap sensors spread throughout the country to a central super computer using an ultra-broadband, synchronized data network. As the central processor IBM has provided its Blue Gene/L supercomputer. It will process streaming data with about 0.5 Terabit per second. Many simple radio antennas connected to the network turn it into a huge radio telescope for cosmological studies. In addition, geophones will turn LOFAR into an earthquake monitoring system and infrasound and meteorology sensors will turn LOFAR into a real-time weather monitoring array for agricultural applications. LOFAR is the first radio telescopes that can listen to radio signals from the entire sky overhead, on all time scales, at a large range of frequencies, and even look back in time for a couple of seconds. The main strength of LOFAR are surveys. One goal is to detect the first generation of black holes and galaxies in the universe during the epoch of reionization and study hydrogen formed after the big bang. LOFAR is also an ideal system to discover transient and sporadic radio signals. Likely transient sources to be discovered with LOFAR are bursting stars and Jupiter-like planets, gamma-ray bursts, radio outbursts from black holes, but also lightning on Earth and even radio flashes from ultra-high energy cosmic particles hitting the Earth atmosphere. Some LOFAR prototypes have recently been built. They have produced the first instantaneous all-sky maps and discovered the radio emission from cosmic particle air showers

Radio Detection of Cosmic Particles with LOFAR

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Atmosphere-Corrected Phase-Referencing

Contains fulltext : 33252.pdf ( ) (Open Access)One major problem of phase-referencing VLBI observations are phase errors due to the unknown tropospheric zenith delay at each antenna. These errors degrade the quality of the phase-referenced image and limit the achievable astrometric accuracy. We will present and compare two independent methods to estimate the zenith delay offset at each antenna. The zenith delay offsets can then be used to correct the data. These corrections improve the quality of the phase-referenced image and an astrometric accuracy of 10 muas can be achieved. With this accuracy, measurements of proper motions in the Local Group become feasible

The Radio/X-Ray Correlation and the Unification of Low Power Black Holes

Contains fulltext : 32296.pdf (publisher's version ) (Open Access)We present a unification scheme for active galactic nuclei (AGN) and black hole X-ray binaries (XRBs) using a symbiotic disk/jet model. Scale invariance and energy conservation are used to derive analytical scaling laws for the emission of a jet and allow us to identify the main parameters of the system: the mass of the central black hole and the accretion rate. The developed model can be used to argue for a unifying view of all weakly accreting black holes: a unification of XRBs and AGN. We classify the zoo of AGN in jet and disk dominated sources and test the unification scheme of weakly accreting sources by establishing a universal radio/X-ray correlation for XRBs and AGN. We briefly discuss jets in highly accreting systems

Report on the ESO Workshop ''mm-wave VLBI with ALMA and Radio Telescopes around the World''

Contains fulltext : 103694.pdf (publisher's version ) (Open Access