Marcel Loose

The Apertif Radio Transient System (ARTS): Design, commissioning, data release, and detection of the first five fast radio bursts

Astronomy & Astrophysics

Fast radio bursts (FRBs) must be powered by uniquely energetic emission mechanisms. This requirem... more Fast radio bursts (FRBs) must be powered by uniquely energetic emission mechanisms. This requirement has eliminated a number of possible source types, but several remain. Identifying the physical nature of FRB emitters arguably requires good localisation of more detections, as well as broad-band studies enabled by real-time alerting. In this paper, we present the Apertif Radio Transient System (ARTS), a supercomputing radio-telescope instrument that performs real-time FRB detection and localisation on the Westerbork Synthesis Radio Telescope (WSRT) interferometer. It reaches coherent-addition sensitivity over the entire field of the view of the primary-dish beam. After commissioning results verified that the system performed as planned, we initiated the Apertif FRB survey (ALERT). Over the first 5 weeks we observed at design sensitivity in 2019, we detected five new FRBs, and interferometrically localised each of them to 0.4–10 sq. arcmin. All detections are broad band, very narrow,...

Download

The Apertif Radio Transient System (ARTS): Design, Commissioning, Data Release, and Detection of the first 5 Fast Radio Bursts

Fast Radio Bursts must be powered by uniquely energetic emission mechanisms. This requirement has... more Fast Radio Bursts must be powered by uniquely energetic emission mechanisms. This requirement has eliminated a number of possible source types, but several remain. Identifying the physical nature of Fast Radio Burst (FRB) emitters arguably requires good localisation of more detections, and broadband studies enabled by real-time alerting. We here present the Apertif Radio Transient System (ARTS), a supercomputing radio-telescope instrument that performs real-time FRB detection and localisation on the Westerbork Synthesis Radio Telescope (WSRT) interferometer. It reaches coherent-addition sensitivity over the entire field of the view of the primarydish beam. After commissioning results verified the system performed as planned, we initiated the Apertif FRB survey (ALERT). Over the first 5 weeks we observed at design sensitivity in 2019, we detected 5 new FRBs, and interferometrically localised each of these to 0.4−10 sq. arcmin. All detections are broad band and very narrow, of order 1 ms duration, and unscattered. Dispersion measures are generally high. Only through the very high time and frequency resolution of ARTS are these hard-to-find FRBs detected, producing an unbiased view of the intrinsic population properties. Most localisation regions are small enough to rule out the presence of associated persistent radio sources. Three FRBs cut through the halos of M31 and M33. We demonstrate that Apertif can localise one-off FRBs with an accuracy that maps magneto-ionic material along well-defined lines of sight. The rate of 1 every ∼7 days next ensures a considerable number of new sources are detected for such study. The combination of detection rate and localisation accuracy exemplified by the 5 first ARTS FRBs thus marks a new phase in which a growing number of bursts can be used to probe our Universe.

Download

Apertif view of the OH megamaser IRAS 10597+5926: OH 18 cm satellite lines in wide-area H I surveys

Astronomy & Astrophysics, 2021

We present the serendipitous detection of the two main OH maser lines at 1667 and 1665 MHz associ... more We present the serendipitous detection of the two main OH maser lines at 1667 and 1665 MHz associated with IRAS 10597+5926 at z⊙ = 0.19612 in the untargeted Apertif Wide-area Extragalactic imaging Survey (AWES), and the subsequent measurement of the OH 1612 MHz satellite line in the same source. With a total OH luminosity of log(L/L⊙) = 3.90 ± 0.03, IRAS 10597+5926 is the fourth brightest OH megamaser (OHM) known. We measure a lower limit for the 1667/1612 ratio of R1612 > 45.9, which is the highest limiting ratio measured for the 1612 MHz OH satellite line to date. OH satellite line measurements provide a potentially valuable constraint by which to compare detailed models of OH maser pumping mechanisms. Optical imaging shows that the galaxy is likely a late-stage merger. Based on published infrared and far ultraviolet fluxes, we find that the galaxy is an ultra-luminous infrared galaxy (ULIRG) with log(LTIR/L⊙) = 12.24 that is undergoing a starburst with an estimated star format...

Download

Chromatic periodic activity down to 120 MHz in a Fast Radio Burst

arXiv: High Energy Astrophysical Phenomena, 2020

Fast radio bursts (FRBs) are extragalactic astrophysical transients whose brightness requires emi... more Fast radio bursts (FRBs) are extragalactic astrophysical transients whose brightness requires emitters that are highly energetic, yet compact enough to produce the short, millisecond-duration bursts. FRBs have thus far been detected between 300 MHz and 8 GHz, but lower-frequency emission has remained elusive. A subset of FRBs is known to repeat, and one of those sources, FRB 20180916B, does so with a 16.3 day activity period. Using simultaneous Apertif and LOFAR data, we show that FRB 20180916B emits down to 120 MHz, and that its activity window is both narrower and earlier at higher frequencies. Binary wind interaction models predict a narrower periodic activity window at lower frequencies, which is the opposite of our observations. Our detections establish that low-frequency FRB emission can escape the local medium. For bursts of the same fluence, FRB 20180916B is more active below 200 MHz than at 1.4 GHz. Combining our results with previous upper-limits on the all-sky FRB rate at...

Download

Optimized trigger for ultra-high-energy cosmic-ray and neutrino observations with the low frequency radio array

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2012

When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency puls... more

Download

A fast radio burst with sub-millisecond quasi-periodic structure

Context. Fast radio bursts (FRBs) are extragalactic radio transients of extraordinary luminosity.... more Context. Fast radio bursts (FRBs) are extragalactic radio transients of extraordinary luminosity. Studying the diverse temporal and spectral behaviour recently observed in a number of FRBs may help determine the nature of the entire class. For example, a fast spinning or highly magnetised neutron star might generate the rotation-powered acceleration required to explain the bright emission. Periodic, sub-second components, suggesting such rotation, were recently reported in one FRB, and potentially in two more. Aims. Here we report the discovery of FRB 20201020A with Apertif, an FRB that shows five components regularly spaced by 0.415 ms. This sub-millisecond structure in FRB 20201020A carries important clues about the progenitor of this FRB specifically, and potentially about that of FRBs in general. We thus contrast its features to the predictions of the main FRB source models. Methods. We perform a timing analysis of the FRB 20201020A components to determine the significance of th...

Download

SKA WP 2.6.1 Software Engineering and Architecture Development: Lessons learned and status report

Presentation delivered jointly with Marcel Loose and Ronald Nijboer (with input from Tim Cornwell... more

Chromatic periodic activity down to 120 MHz in a Fast Radio Burst

arXiv: High Energy Astrophysical Phenomena, 2020

Fast radio bursts (FRBs) are extragalactic astrophysical transients whose brightness requires emi... more Fast radio bursts (FRBs) are extragalactic astrophysical transients whose brightness requires emitters that are highly energetic, yet compact enough to produce the short, millisecond-duration bursts. FRBs have thus far been detected between 300 MHz and 8 GHz, but lower-frequency emission has remained elusive. A subset of FRBs is known to repeat, and one of those sources, FRB 20180916B, does so with a 16.3 day activity period. Using simultaneous Apertif and LOFAR data, we show that FRB 20180916B emits down to 120 MHz, and that its activity window is both narrower and earlier at higher frequencies. Binary wind interaction models predict a narrower periodic activity window at lower frequencies, which is the opposite of our observations. Our detections establish that low-frequency FRB emission can escape the local medium. For bursts of the same fluence, FRB 20180916B is more active below 200 MHz than at 1.4 GHz. Combining our results with previous upper-limits on the all-sky FRB rate at...

Download

Chromatic periodic activity down to 120 megahertz in a fast radio burst

Nature

A bright, high rotation-measure FRB that skewers the M33 halo

Monthly Notices of the Royal Astronomical Society

We report the detection of a bright fast radio burst, FRB 191108, with Apertif on the Westerbork ... more We report the detection of a bright fast radio burst, FRB 191108, with Apertif on the Westerbork Synthesis Radio Telescope. The interferometer allows us to localize the FRB to a narrow 5 arcsec × 7 arcmin ellipse by employing both multibeam information within the Apertif phased-array feed beam pattern, and across different tied-array beams. The resulting sightline passes close to Local Group galaxy M33, with an impact parameter of only 18 kpc with respect to the core. It also traverses the much larger circumgalactic medium (CGM) of M31, the Andromeda Galaxy. We find that the shared plasma of the Local Group galaxies could contribute ∼10 per cent of its dispersion measure of 588 pc cm−3. FRB 191108 has a Faraday rotation measure (RM) of +474 $\pm \, 3$ rad m−2, which is too large to be explained by either the Milky Way or the intergalactic medium. Based on the more moderate RMs of other extragalactic sources that traverse the halo of M33, we conclude that the dense magnetized plasma ...

Cobalt: A GPU-based correlator and beamformer for LOFAR

Astronomy and Computing

For low-frequency radio astronomy, software correlation and beamforming on general purpose hardwa... more For low-frequency radio astronomy, software correlation and beamforming on general purpose hardware is a viable alternative to custom designed hardware. LOFAR, a newgeneration radio telescope centered in the Netherlands with international stations in Germany, France, Ireland, Poland, Sweden and the UK, has successfully used software real-time processors based on IBM Blue Gene technology since 2004. Since then, developments in technology have allowed us to build a system based on commercial off-the-shelf components that combines the same capabilities with lower operational cost. In this paper we describe the design and implementation of a GPU-based correlator and beamformer with the same capabilities as the Blue Gene based systems. We focus on the design approach taken, and show the challenges faced in selecting an appropriate system. The design, implementation and verification of the software system shows the value of a modern test-driven development approach. Operational experience, based on three years of operations, demonstrates that a general purpose system is a good alternative to the previous supercomputer-based system or custom-designed hardware.

Download

Optimized trigger for ultra-high-energy cosmic-ray and neutrino observations with the low frequency radio array

by Ger Van Diepen, Matthias Steinmetz, A. Gunst, and Marcel Loose

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2012

When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency puls... more When an ultra-high energy neutrino or cosmic ray strikes the Lunar surface a radio-frequency pulse is emitted. We plan to use the LOFAR radio telescope to detect these pulses. In this work we propose an efficient trigger implementation for LOFAR optimized for the observation of short radio pulses. 95.55.Jz, 95.75.Wx, 95.85.Bh, 95.85.Ry

Download

<title>Strategies for end-to-end modeling of next-generation mm- and radio telescopes</title>

by Ger Van Diepen and Marcel Loose

Integrated Modeling of Telescopes, 2002

The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulatio... more The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulation of the physical telescope structures and geometries. The complexity of the RF and IF chains, the digital signal processing systems and the increasing importance of data-processing pipelines forces us to model the full dataflow through the system. This is true is particular for telescopes based on phased array technology, where the physical antenna structure is static and relatively simple. This paper distinguishes between various categories of modeling and simulation. In functional modeling the full functional breakdown of the system is simulated. This allows for the identification of bottlenecks in the flow, gives options for failure mode analysis, for the study of control topologies and real-time responsiveness and for the verification of interfaces and functional behavior. In fact a proper functional model is a virtual mockup of the entire system. This immediately points at a limita...

Data Analysis in the LOFAR Long Term Archive

by Fokke Dijkstra, Ger Van Diepen, Dennis H van Dok, and Marcel Loose

The LOFAR Long Term Archive (LTA) is a distributed information system that provides integrated se... more The LOFAR Long Term Archive (LTA) is a distributed information system that provides integrated services for data analysis as well as long term preservation of astronomical datasets and their provenance. The data analysis capabilities are provided by a federated system that integrates a central catalog and client user interfaces provided by Astro-Wise with processing pipelines running on Grid based and University HPC clusters. The framework used for data analysis ensures that proper authorization and access rules are applied and that generated data products are ingested into the storage part of the Long Term Archive. The ingest process includes information about data provenance. This paper presents the architecture of the processing framework of the LTA.

LOFAR Self-Calibration Using a Blackboard Software Architecture

One of the major challenges for the self-calibration of the new generation of radio telescopes is... more One of the major challenges for the self-calibration of the new generation of radio telescopes is to handle the sheer amount of observational data. For LOFAR, an average observation consists of several tens of terabytes of data. Fortunately, many operations can be done in parallel on only part of the data. So, one way to take up this challenge is to employ a large cluster of computers and to distribute both data and computing power. This paper focuses on the architectural design of the LOFAR self-calibration system, which is loosely based on the Blackboard architectural pattern. Key design consideration was to provide maximum scalability by complete separation of the global controller---issuing sequences of commands---on the one side; and the local controllers---controlling the so-called `kernels' that execute the commands---on the other side. In between, resides a database system that acts as a shared memory for the global and local controllers by storing the commands and the r...

Workshop on Integrated Modeling of Telescopes

The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulatio... more The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulation of the physical telescope structures and geometries. The complexity of the RF and IF chains, the digital signal processing systems and the increasing importance of data-processing pipelines forces us to model the full dataflow through the system. This is true is particular for telescopes based on phased array technology, where the physical antenna structure is static and relatively simple. This paper distinguishes between various categories of modeling and simulation. In functional modeling the full functional breakdown of the system is simulated. This allows for the identification of bottlenecks in the flow, gives options for failure mode analysis, for the study of control topologies and real-time responsiveness and for the verification of interfaces and functional behavior. In fact a proper functional model is a virtual mockup of the entire system. This immediately points at a limita...

<title>Strategies for end-to-end modeling of next-generation mm- and radio telescopes</title>

Integrated Modeling of Telescopes, 2002

The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulatio... more The functional end-to-end modeling of large mm- and radio-telescopes extends beyond the simulation of the physical telescope structures and geometries. The complexity of the RF and IF chains, the digital signal processing systems and the increasing importance of data-processing pipelines forces us to model the full dataflow through the system. This is true is particular for telescopes based on phased array technology, where the physical antenna structure is static and relatively simple. This paper distinguishes between various categories of modeling and simulation. In functional modeling the full functional breakdown of the system is simulated. This allows for the identification of bottlenecks in the flow, gives options for failure mode analysis, for the study of control topologies and real-time responsiveness and for the verification of interfaces and functional behavior. In fact a proper functional model is a virtual mockup of the entire system. This immediately points at a limita...

Data Analysis in the LOFAR Long Term Archive

The LOFAR Long Term Archive (LTA) is a distributed information system that provides integrated se... more The LOFAR Long Term Archive (LTA) is a distributed information system that provides integrated services for data analysis as well as long term preservation of astronomical datasets and their provenance. The data analysis capabilities are provided by a federated system that integrates a central catalog and client user interfaces provided by Astro-Wise with processing pipelines running on Grid based and University HPC clusters. The framework used for data analysis ensures that proper authorization and access rules are applied and that generated data products are ingested into the storage part of the Long Term Archive. The ingest process includes information about data provenance. This paper presents the architecture of the processing framework of the LTA.

Related Authors

Uploads

Papers by Marcel Loose

Log In