A5015952275- Radio Astronomy Observations and Technology
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Sensor Technology
- Astrophysical Phenomena and Observations
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Advanced Frequency and Time Standards
- Astronomical Observations and Instrumentation
- Superconducting and THz Device Technology
- Astronomy and Astrophysical Research
- Geomagnetism and Paleomagnetism Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Radio Wave Propagation Studies
- Antenna Design and Optimization
- Statistical and numerical algorithms
- Scientific Measurement and Uncertainty Evaluation
- GNSS positioning and interference
- Precipitation Measurement and Analysis
- Particle Accelerators and Free-Electron Lasers
- Advanced Physical and Chemical Molecular Interactions
Astronomy and Space
2017-2025
Commonwealth Scientific and Industrial Research Organisation
2017-2025
International Centre for Radio Astronomy Research
2017-2019
Curtin University
2017-2019
Netherlands Institute for Radio Astronomy
2014-2019
Max Planck Institute for Radio Astronomy
2011-2018
Max Planck Society
2013-2015
Max Planck Innovation
2013-2015
Max Planck Institute for Astrophysics
2012
Abstract We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. is a high-gain ( ${\sim}2.8\,\mbox{K Jy}^{-1}$ ) low-system temperature ${\sim}18\,\mbox{K at }20\,\mbox{cm}$ array that currently operates 580–1 670 MHz can produce tied-array beams suitable observations. This paper presents MeerTime Large Survey Project commissioning with PTUSE. Highlights include...
Aims. This work provides an update to existing reconstructions of the Galactic Faraday rotation sky by processing almost all data sets available at end year 2020. Observations extra-Galactic sources in recent years have further illuminated previously underconstrained southern celestial sky, as well parts inner disc Milky Way, along with other regions. has culminated all-sky set 55 190 points, thereby comprising a significant expansion on 41 330 used previous works. At same time, this novelty...
Faraday rotation measurements using the current and next generation of low-frequency radio telescopes will provide a powerful probe astronomical magnetic fields. However, achieving full potential these requires accurate removal time-variable ionospheric contribution. We present ionFR, code that calculates amount for specific epoch, geographic location, line-of-sight. ionFR uses number publicly available, GPS-derived total electron content maps most recent release International Geomagnetic...
Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out edges of magnetosphere. Detecting correlated mode changes in multi-wavelength emission is therefore key understanding physical relationship between these sites. Through simultaneous observations, we have detected synchronous switching and X-ray properties PSR B0943+10. When pulsar a sustained 'bright' mode, X-rays show only an un-pulsed, non-thermal component. Conversely,...
We present the Multifrequency Snapshot Sky Survey (MSSS), first northern-sky LOFAR imaging survey. In this introductory paper, we describe in detail motivation and design of Compared to previous radio surveys, MSSS is exceptional due its intrinsic multifrequency nature providing information about spectral properties detected sources over more than two octaves (from 30 160 MHz). The broadband frequency coverage, together with fast survey speed generated by LOFAR's multibeaming capabilities,...
We present the discovery of PSR J0250+5854, a radio pulsar with spin period 23.5 s. This is slowest-spinning known. J0250+5854 was discovered by LOFAR Tied-Array All-Sky Survey (LOTAAS), an all-northern-sky survey for pulsars and fast transients at central observing frequency 135 MHz. subsequently detected pulsations from in interferometric images Two-meter Sky Survey, allowing subarcsecond localization. This, along pre-discovery detection 2 years prior, allowed us to measure spin-period...
We report the detection of 48 millisecond pulsars (MSPs) out 75 observed thus far using LOFAR in frequency range 110-188 MHz. have also detected three MSPs nine 38-77 This is largest sample ever at these low frequencies, and half were for first time frequencies below 200 present average pulse profiles MSPs, their effective widths, flux densities compare with higher observing frequencies. The flux-calibrated, multifrequency are publicly available via EPN Database Pulsar Profiles. values...
Fast radio bursts (FRBs) are millisecond signals that exhibit dispersion larger than what the Galactic electron density can account for. We have conducted a 1446 h survey for FRBs at 145 MHz, covering total of 4193 deg2 on sky. used UK station low frequency array (LOFAR) telescope – Rawlings Array accompanied majority time by LOFAR Nançay, observing same fields frequency. Our real-time search backend, Advanced Radio Transient Event Monitor and Identification System artemis, utilizes graphics...
We present an overview of the LOFAR Tied-Array All-Sky Survey (LOTAAS) for radio pulsars and fast transients. The survey uses high-band antennas Superterp, dense inner part core, to northern sky (dec > 0 deg) at a central observing frequency 135 MHz. A total 219 tied-array beams (coherent summation station signals, covering 12 square degrees), as well three incoherent (covering 67 degrees) are formed in each pointing. For ofthe 222 beams, intensity is recorded 491.52 us time resolution. Each...
We determined Faraday rotation measures (RMs) towards 137 pulsars in the northern sky, using Low-Frequency Array (LOFAR) observations at 110-190 MHz. This low-frequency RM catalogue, largest to date, improves precision of existing measurements on average by a factor 20 - due low frequency and wide bandwidth data, aided synthesis method. report RMs 25 for first time. The were corrected ionospheric increase accuracy our catalogue approximately 0.1 rad m$^{\rm -2}$. correction is currently...
The smooth spin-down of young pulsars is perturbed by two non-deterministic phenomenon, glitches and timing noise. Although the noise provides insights into nuclear plasma physics at extreme densities, it acts as a barrier to high-precision pulsar experiments. An improved methodology based on Bayesian inference developed simultaneously model stochastic deterministic parameters for sample 85 high-$\dot{E}$ radio observed $\sim$ 10 years with 64-m Parkes telescope. Timing known be red process...
A Faraday rotation measure (RM) catalogue, or RM Grid, is a valuable resource for the study of cosmic magnetism. Using second data release (DR2) from LOFAR Two-metre Sky Survey (LoTSS), we have produced catalogue 2461 extragalactic high-precision values across 5720 deg$^{2}$ sky (corresponding to polarized source areal number density $\sim$0.43 deg$^{-2}$). The linear polarization and properties were derived using synthesis Stokes $Q$ $U$ channel images at an angular resolution 20''...
M87 is a giant elliptical galaxy located in the centre of Virgo cluster, which harbours supermassive black hole mass 6.4x10^9 M_sun, whose activity responsible for extended (80 kpc) radio lobes that surround galaxy. The energy generated by matter falling onto central ejected and transferred to intra-cluster medium via relativistic jet morphologically complex systems buoyant bubbles, rise towards edges halo. Here we present first observations made with new Low-Frequency Array (LOFAR) at...
The low frequency array (LOFAR), is the first radio telescope designed with capability to measure emission from cosmic-ray induced air showers in parallel interferometric observations. In $\sim 2\,\mathrm{years}$ of observing, 405 events energy range $10^{16} - 10^{18}\,\mathrm{eV}$ have been detected band $30 80\,\mathrm{MHz}$. Each these registered up $\sim1000$ independent antennas resulting measurements unprecedented detail. This article describes dataset, as well analysis pipeline, and...
The characteristic outer scale of turbulence and the ratio random to ordered components magnetic field are key parameters characterise in interstellar gas, which affects propagation cosmic rays within Galaxy. We provide new constraints those two parameters. use LOw Frequency ARray (LOFAR) image diffuse continuum emission Fan region at (l,b) (137.0,+7.0) 80"x70" resolution range [146,174] MHz. detect multi-scale fluctuations Galactic synchrotron compute their power spectrum. Applying...
Dispersion in the interstellar medium is a well known phenomenon that follows simple relationship, which has been used to predict time delay of dispersed radio pulses since late 1960s. We performed wide-band simultaneous observations four pulsars with LOFAR (at 40-190 MHz), 76-m Lovell Telescope 1400 MHz) and Effelsberg 100-m 8000 test accuracy dispersion law over broad frequency range. In this paper we present results these show accurate better than 1 part 100000 across our observing band....
We present first results from a LOFAR census of non-recycled pulsars. The includes almost all such pulsars known (194 sources) at declinations ${\rm Dec}> 8^\circ$ and Galactic latitudes $|{\rm Gb}| > 3^\circ$, regardless their expected flux densities scattering times. Each pulsar was observed for $\geq 20$ minutes in the contiguous frequency range 110--188 MHz. Full-Stokes data were recorded. dispersion measures, densities, calibrated total intensity profiles 158 detected sample. median...
We present the highest-quality polarisation profiles to date of 16 non-recycled pulsars and four millisecond pulsars, observed below 200 MHz with LOFAR high-band antennas. Based on profiles, we perform an initial investigation expected observational effects resulting from propagation polarised emission in pulsar magnetosphere interstellar medium. The predictions magnetospheric birefringence have been tested using spectra pulse width fractional multifrequency data. derived offer only partial...
We have conducted two pilot surveys for radio pulsars and fast transients with the Low-Frequency Array (LOFAR) around 140 MHz here report on first low-frequency fast-radio burst limit discovery of new pulsars. The survey, LOFAR Pilot Pulsar Survey (LPPS), observed a large fraction northern sky, ~1.4 x 10^4 sq. deg, 1-hr dwell times. Each observation covered ~75 deg using 7 independent fields formed by incoherently summing high-band antenna fields. second Tied-Array (LOTAS), spanned ~600...
Magnetic fields pervade the interstellar medium (ISM), but are difficult to detect and characterize. The new generation of low-frequency radio telescopes, such as Low Frequency Array (LOFAR: a Square Kilometre Array-low pathfinder), provides advancements in our capability probing Galactic magnetism through polarimetry. Maps diffuse polarized emission associated Faraday rotation can be used infer properties of, trace structure in, magnetic ISM. However, date very little sky has been probed at...
Aims. This paper discusses the spectral occupancy for performing radio astronomy with Low-Frequency Array (LOFAR), a focus on imaging observations.
We measure the effects of interstellar scattering on average pulse profiles from 13 radio pulsars with simple shapes. use data LOFAR High Band Antennas, at frequencies between 110 and 190~MHz. apply a forward fitting technique, simultaneously determine intrinsic shape, assuming single Gaussian component profiles. find that constant $\tau$, associated by thin screen, has power-law dependence frequency $\tau \propto \nu^{-\alpha}$, indices ranging $\alpha = 1.50$ to $4.0$, despite simplest...