A5086641325- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Planetary Science and Exploration
- Galaxies: Formation, Evolution, Phenomena
- Space Satellite Systems and Control
- Astronomy and Astrophysical Research
- Ionosphere and magnetosphere dynamics
- Adaptive optics and wavefront sensing
- GNSS positioning and interference
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Advanced Optical Sensing Technologies
- Electromagnetic Compatibility and Measurements
- Ultra-Wideband Communications Technology
- Stellar, planetary, and galactic studies
- Advanced Data Compression Techniques
- Computational Physics and Python Applications
University of Amsterdam
2016-2022
Astronomical Institute of the Slovak Academy of Sciences
2021
Leiden University
2017
The mass assembly history of the Milky Way can inform both theory galaxy formation and underlying cosmological model. Thus, observational constraints on properties its baryonic dark matter contents are sought. Here, we show that hypervelocity stars (HVSs) in principle provide such constraints. We model observed velocity distribution HVSs, produced by tidal break-up stellar binaries caused Sgr A*. Considering a Galactic Centre (GC) binary population consistent with inferred more...
The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted traditional astrophysical models. If genuine, a deeper may lead to fluctuations on signal degree scales (up 1~Kelvin in rms), allowing these be detectable nearly 50~times shorter integration compared previous predictions. We commenced "AARTFAAC Cosmic Explorer" (ACE) program, employs AARTFAAC wide-field imager, measure or set limits power spectrum of redshift range $z = 17.9-18.6$...
The Amsterdam–ASTRON Radio Transients Facility and Analysis Center (AARTFAAC) all-sky monitor is a sensitive, real-time transient detector based on the Low Frequency Array (LOFAR). It generates images of low frequency radio sky with spatial resolution tens arcmin, MHz bandwidths, time cadence few seconds, while simultaneously but independently observing LOFAR. image timeseries then monitored for short bright transients. On detection transient, latency trigger will be generated LOFAR, which...
The nature of the central engines gamma-ray bursts (GRBs) and composition their relativistic jets are still under debate. If Poynting flux dominated rather than baryon dominated, a coherent radio flare from magnetic re-connection events might be expected with prompt emission. There two competing models for GRBs; black hole or newly formed milli-second magnetar. engine is magnetar it predicted to produce emission as persistent flaring activity. In this paper, we present deepest limits date...
We report on the detection of extreme giant pulses (GPs) from one oldest-known pulsars, highly variable PSR B0950+08, with Amsterdam-ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC), a parallel transient instrument operating as subsystem LOw Frequency ARray (LOFAR). During processing our Northern Hemisphere survey for low-frequency radio transients, sample 275 fluences ranging 42 to 177 kJy ms were detected in one-second snapshot images. The brightest are an order magnitude...
We present a method for calibrating the flux density scale images generated by Amsterdam ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC). AARTFAAC produces stream of all-sky at rate one second in order to survey Northern Hemisphere short duration, low frequency transients, such as prompt EM counterpart gravitational wave events, magnetar flares, blazars, and other yet unobserved phenomena. Therefore, an independent scaling solution per image is calculated via bootstrapping,...
We report the experimental setup and overall results of AARTFAAC wide-field radio survey, which consists observing sky within 50$^\circ$ Zenith, with a bandwidth 3.2$\,$MHz, at cadence 1$\,$s, for 545$\,$h. This yielded nearly 4 million snapshots, two per second, on average 4800 square degrees sensitivity around 60$\,$Jy. find populations transient events, one originating from PSR$\,$B0950$+$08 strong ionospheric lensing as well single candidate an extragalactic transient, peak flux density...
Aims: Contamination from bright diffuse Galactic thermal and non-thermal radio emission poses crucial challenges in experiments aiming to measure the 21-cm signal of neutral hydrogen Cosmic Dawn Epoch Reionization. If not included calibration, this can severely impact analysis extraction experiments. We examine large-scale at 122~MHz, around North Celestial Pole, using AARTFAAC-HBA system. Methods: In pilot project, we present first-ever wide-field image produced with a single sub-band data...
We report the discovery of bright, fast, radio flashes lasting tens seconds with AARTFAAC high-cadence all-sky survey at 60 MHz. The vast majority these coincide known, bright sources that brighten by factors up to 100 during such an event. attribute them magnification events induced plasma near Earth, most likely in densest parts ionosphere. They can occur both relative isolation, otherwise quiescent ionospheric conditions, and large clusters more turbulent conditions. Using a toy model, we...
We present a methodology for automated real-time analysis of radio image data stream with the goal to find transient sources. Contrary previous works, transients we are interested in occur on time-scale where dispersion starts play role, so must search higher-dimensional space and yet work fast enough keep up real time. The approach consists five main steps: quality control, source detection, association, flux measurement, physical parameter inference. parallelized methods based convolutions...
We report on simultaneous 30 - 60 MHz LOFAR / AARTFAAC12 radio observations and CAMS low-light video of +4 to -10 magnitude meteors at the peak Perseid meteor shower August 12/13, 2020. 204 trains were imaged in both optical domain. Aside from scattered artificial sources, we identify broadband emission many persistent trains, one which lingered for up 6 minutes. Unexpectedly, fewer recorded when experiment was repeated during 2020 Geminids 2021 Quadrantids. Intrinsic reported earlier by...
The Amsterdam-ASTRON Radio Transients Facility And Analysis Center (AARTFAAC) all sky monitor is a sensitive, real time transient detector based on the Low Frequency Array (LOFAR). It generates images of low frequency radio with spatial resolution 10s arcmin, MHz bandwidths, and cadence few seconds, while simultaneously but independently observing LOFAR. image timeseries then monitored for short bright transients. On detection transient, latency trigger will be generated LOFAR, which can...
Dense aperture arrays provide key benefits in modern astrophysical research. They are flexible, employing cheap receivers, while relying on the ever more sophisticated compute back-end to deal with complexities of signal processing required for optimal use. Their advantage is that they offer very large fields view and readily scalable any size, all other things being equal. Since represent "software telescopes", science cases these can be applied quite broad. Here, we describe calibration...
We present a methodology for automated real-time analysis of radio image data stream with the goal to find transient sources. Contrary previous works, transients we are interested in occur on time-scale where dispersion starts play role, so must search higher-dimensional space and yet work fast enough keep up real time. The approach consists five main steps: quality control, source detection, association, flux measurement, physical parameter inference. parallelized methods based convolutions...
Radio astronomy has entered an era of fast-cadence imaging [Prasad and Wijnholds, 2012]. Among others, this allows for transient hunting in the long-wavelength regime. For example, fast radio bursts [Petroff et al., 2019] have yet to be discovered frequencies that LOFAR's AARTFAAC [van Haarlem 2013, Prasad 2012] is operational in. Searching such events gained much interest recent years. a sensitive all-sky transients program with spatial resolution 10s arcmin at low (30-80 MHz). It was...