scholarly journals High time resolution and polarization properties of ASKAP-localized fast radio bursts

2020 ◽  
Vol 497 (3) ◽  
pp. 3335-3350 ◽  
Author(s):  
Cherie K Day ◽  
Adam T Deller ◽  
Ryan M Shannon ◽  
Hao Qiu(邱昊) ◽  
Keith W Bannister ◽  
...  
Keyword(s):  
Time Resolution ◽  
Local Environment ◽  
High Time ◽  
Frequency Resolution ◽  
Host Galaxy ◽  
High Time Resolution ◽  
Radio Bursts ◽  
Diverse Range ◽  
Scattering Time ◽  
The Impact

ABSTRACT Combining high time and frequency resolution full-polarization spectra of fast radio bursts (FRBs) with knowledge of their host galaxy properties provides an opportunity to study both the emission mechanism generating them and the impact of their propagation through their local environment, host galaxy, and the intergalactic medium. The Australian Square Kilometre Array Pathfinder (ASKAP) telescope has provided the first ensemble of bursts with this information. In this paper, we present the high time and spectral resolution, full polarization observations of five localized FRBs to complement the results published for the previously studied ASKAP FRB 181112. We find that every FRB is highly polarized, with polarization fractions ranging from 80 to 100 per cent, and that they are generally dominated by linear polarization. While some FRBs in our sample exhibit properties associated with an emerging archetype (i.e. repeating or apparently non-repeating), others exhibit characteristic features of both, implying the existence of a continuum of FRB properties. When examined at high time resolution, we find that all FRBs in our sample have evidence for multiple subcomponents and for scattering at a level greater than expected from the Milky Way. We find no correlation between the diverse range of FRB properties (e.g. scattering time, intrinsic width, and rotation measure) and any global property of their host galaxy. The most heavily scattered bursts reside in the outskirts of their host galaxies, suggesting that the source-local environment rather than the host interstellar medium is likely the dominant origin of the scattering in our sample.

scholarly journals The High Time and Frequency Resolution Capabilities of the Murchison Widefield Array

2015 ◽  
Vol 32 ◽  
Author(s):  
S. E. Tremblay ◽  
S. M. Ord ◽  
N. D. R. Bhat ◽  
S. J. Tingay ◽  
B. Crosse ◽  
...  
Keyword(s):  
Radio Emission ◽  
Time Resolution ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Radio Bursts ◽  
Radio Telescopes ◽  
Initial Design ◽  
Imaging Telescope ◽  
Murchison Widefield Array

AbstractThe science cases for incorporating high time resolution capabilities into modern radio telescopes are as numerous as they are compelling. Science targets range from exotic sources such as pulsars, to our Sun, to recently detected possible extragalactic bursts of radio emission, the so-called fast radio bursts (FRBs). Originally conceived purely as an imaging telescope, the initial design of the Murchison Widefield Array (MWA) did not include the ability to access high time and frequency resolution voltage data. However, the flexibility of the MWA’s software correlator allowed an off-the-shelf solution for adding this capability. This paper describes the system that records the 100 μs and 10 kHz resolution voltage data from the MWA. Example science applications, where this capability is critical, are presented, as well as accompanying commissioning results from this mode to demonstrate verification.

High Time-Resolution Studies of Jupiter's Radio Bursts

1967 ◽  
Vol 148 ◽  
pp. 511 ◽  
Author(s):  
M. A. Gordon ◽  
J. W. Warwick
Keyword(s):  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Radio Bursts

scholarly journals Fourier Analysis of Radio Bursts Observed with Very High Time Resolution

Solar Physics ◽  
2014 ◽  
Vol 290 (1) ◽  
pp. 169-180 ◽  
Author(s):  
B. P. Da̧browski ◽  
M. Karlický ◽  
P. Rudawy
Keyword(s):  
Fourier Analysis ◽  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Radio Bursts ◽  
Very High

scholarly journals The High Time Resolution Universe surveys for pulsars and fast transients

2012 ◽  
Vol 8 (S291) ◽  
pp. 29-34 ◽  
Author(s):  
Michael J. Keith
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
Gamma Ray ◽  
Galactic Plane ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Galactic Latitude ◽  
Millisecond Pulsars ◽  
Bank System

AbstractThe High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

scholarly journals The impact of cloudiness and cloud type on the atmospheric heating rate of black and brown carbon

2020 ◽  
Author(s):  
Luca Ferrero ◽  
Asta Gregorič ◽  
Griša Močnik ◽  
Martin Rigler ◽  
Sergio Cogliati ◽  
...  
Keyword(s):  
Time Resolution ◽  
Direct Determination ◽  
High Time ◽  
High Time Resolution ◽  
Cloud Type ◽  
Heating Rates ◽  
Brown Carbon ◽  
Clear Sky ◽  
Sky Conditions ◽  
The Impact

Abstract. We experimentally quantified the impact of cloud fraction and cloud type on the heating rates (HRs) of black and brown carbon (HRBC and HRBrC).In particular, in this work, we examine in more detail the average cloud effect (Ferrero et al., 2018) using high time-resolution measurements of aerosol absorption at multiple-wavelengths coupled with spectral measurements of the direct, diffuse and surface reflected radiation and lidar data in the Po Valley. The experimental set-up allowed a direct determination of HRBC and HRBrC in any sky condition. The highest values of total HR were found in the middle of the winter (1.43 ± 0.05 K day−1) while the lowest in spring (0.54 ± 0.02 K day−1) Overall the HRBrC accounted for 13.7 ± 0.2 % of the total HR, the BrC being characterized by an AAE of 3.49 ± 0.01. Simultaneously, sky conditions were classified (from clear-sky to cloudy) in terms of fraction of sky covered by clouds (oktas) and cloud types. Cloud types were grouped as a function of altitude into the following classes: 1) low level ( 7 km) cirrus, cirrocumulus-cirrostratus. Measurements carried out in different sky conditions at high-time resolution showed a constant decrease of HR with increasing cloudiness of the atmosphere enabling us to quantify for the first time the bias (in %) in the aerosol HR introduced by improperly assuming clear-sky conditions in radiative transfer calculations. In fact, during the campaign, clear sky conditions were only present 23 % of the time while the remaining time (77 %) was characterized by cloudy conditions. Our results show that, by incorrectly assuming clear-sky conditions, the HR of light absorbing aerosol can be largely overestimated (by 50 % in low cloudiness, oktas = 1–2), up to over 400 % (in complete overcast conditions, i.e., oktas = 7–8). The impact of different cloud types on the HR compared to a clear sky condition was also investigated. Cirrus were found to have a modest impact, decreasing the HRBC and HRBrC by −1– −5 %. Cumulus decreased the HRBC and HRBrC by −31 ± 12 and −26 ± 7 %, respectively, while cirrocumulus-cirrostratus by −60 ± 8 and −54 ± 4 %, which was comparable to the impact of altocumulus (−60 ± 6 and −46 ± 4 %). A high impact on HRBC and HRBrC was found for stratocumulus (−63 ± 6 and −58 ± 4 %, respectively) and altostratus (−78 ± 5 and −73 ± 4 %, respectively), although the highest impact was found to be associated to stratus that suppressed the HRBC and HRBrC by −85 ± 5 and −83 ± 3 %, respectively. Additionally, the cloud influence on the radiation spectrum that interacts with the absorbing aerosol was investigated. Black and brown carbon (BC and BrC) have different spectral responses (a different absorption Angstrom exponent, AAE) and our results show that the presence of clouds causes a greater decrease for the HRBC with respect to to HRBrC going clear sky to complete overcast conditions; the observed the difference is 12 ± 6 %. This means that, compared to BC, BrC is more efficient in heating the surrounding atmosphere in cloudy conditions than in clear sky. Overall, this study extends the results of a previous work (Ferrero et al., 2018), highlighting the need to take into account both the role of cloudiness and of different cloud types to better estimate the HR associated to both BC and BrC, and in turn decrease the uncertainties associated to the quantification of the impact of these species on radiation and climate.

Searching for fast radio bursts with the high time resolution universe: North survey

2017 ◽  
Author(s):  
Laura G. Spitler ◽  
Marina Berezina ◽  
David J. Champion ◽  
Ralph Eatough ◽  
Heino Falke ◽  
...  
Keyword(s):  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Radio Bursts

scholarly journals Microsecond polarimetry of the repeating FRB 20180916B

2020 ◽  
Author(s):  
Kenzie Nimmo ◽  
Jason Hessels ◽  
Aard Keimpema ◽  
Anne Archibald ◽  
James Cordes ◽  
...  
Keyword(s):  
Time Resolution ◽  
Position Angle ◽  
High Time ◽  
Dispersion Measure ◽  
High Time Resolution ◽  
Radio Bursts ◽  
Signal To Noise ◽  
Propagation Effects ◽  
Local Medium ◽  
Very High

Abstract Fast radio bursts (FRBs) exhibit a wide variety of spectral, temporal and polarimetric properties, which can unveil clues into their emission physics and propagation effects in the local medium. FRBs are challenging to study at very high time resolution due to the precision needed to constrain the dispersion measure, signal-to-noise limitations, and also scattering from the intervening medium. Here we present the high-time-resolution (down to 1 μs) polarimetric properties of four 1.7-GHz bursts from the repeating FRB 20180916B, which were detected in voltage data during observations with the European VLBI Network. In these bursts we observe a range of emission timescales spanning three orders of magnitude, the shortest component width reaching 3-4 μs (below which we are limited by scattering). We demonstrate that all four bursts are highly linearly polarised (≥ 80%), show no evidence for significant circular polarisation (≤ 15%), and exhibit a constant polarisation position angle during and between bursts. On short timescales (≤ 100 μs), however, there appear to be subtle (few degree) polarisation position angle variations across the burst profiles. These observational results are most naturally explained in an FRB model where the emission is magnetospheric in origin, as opposed to models where the emission originates at larger distances in a relativistic shock.

scholarly journals A DMA-train for precision measurement of sub 10-nm aerosol dynamics

2016 ◽  
Author(s):  
Dominik Stolzenburg ◽  
Gerhard Steiner ◽  
Paul M. Winkler
Keyword(s):  
Particle Size ◽  
Time Resolution ◽  
Transfer Functions ◽  
Particle Formation ◽  
High Time ◽  
High Time Resolution ◽  
New Particle Formation ◽  
Aerosol Dynamics ◽  
Water Based ◽  
The Impact

Abstract. Measurements of aerosol dynamics in the sub-10 nm size range are crucially important for quantifying the impact of new particle formation onto the global budget of cloud condensation nuclei. Here we present the development and characterization of a differential mobility analyzer – train (DMA-train), operating six DMAs in parallel for high time-resolution particle size-distribution measurements below 10 nm. The DMAs are operated at six different but fixed voltages and hence sizes, together with six state-of-the-art condensation particle counters. Two Airmodus A 10 particle size magnifiers (PSM) are used for channels below 2.5 nm while sizes above 2.5 nm are detected by TSI 3776 butanol or TSI 3788 water based CPCs. We report the transfer functions and characteristics of six identical Grimm S-DMAs as well as the calibration of a butanol-based TSI model 3776 CPC, a water-based TSI model 3788 CPC and an Aimodus A10 PSM. We find cut-off diameters similar to those reported in the literature. The performance of the DMA-train is tested with a rapidly changing aerosol of a tungsten oxide particle generator during warm-up. Additionally we report a measurement of new particle formation taken during a nucleation event in the CLOUD chamber experiment at CERN. We find that the DMA-train is able to bridge the gap between currently well-established measurement techniques in the cluster-particle transition regime, providing high time-resolution and accurate size information of neutral and charged particles even at atmospheric particle concentrations.

scholarly journals LOFT-e: Localisation Of Fast Transients with e-MERLIN

2017 ◽  
Vol 13 (S337) ◽  
pp. 422-423
Author(s):  
C. R. H. Walker ◽  
R. P. Breton ◽  
P. A. Harrison ◽  
A. Holloway ◽  
M. J. Keith ◽  
...  
Keyword(s):  
Full Advantage ◽  
Real Time ◽  
Time Resolution ◽  
Observation Time ◽  
Field Of View ◽  
High Time ◽  
High Time Resolution ◽  
Radio Bursts ◽  
Raw Data ◽  
Fast Transients

AbstractThe majority of fast radio bursts (FRBs) are poorly localised, hindering their potential scientific yield as galactic, intergalactic, and cosmological probes. LOFT-e, a digital backend for the U.K.’s e-MERLIN seven-telescope interferometer will provide commensal search and real-time detection of FRBs, taking full advantage of its field of view (FoV), sensitivity, and observation time. Upon burst detection, LOFT-e will store raw data offline, enabling the sub-arcsecond localisation provided by e-MERLIN and expanding the pool of localised FRBs. The high-time resolution backend will additionally introduce pulsar observing capabilities to e-MERLIN.

scholarly journals Conducting the deepest all-sky pulsar survey ever: the all-sky High Time Resolution Universe survey

2012 ◽  
Vol 8 (S291) ◽  
pp. 53-56
Author(s):  
Cherry Ng ◽  
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
Binary Systems ◽  
Galactic Plane ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Similar System ◽  
Black Hole Binaries ◽  
The Uk

AbstractThe extreme conditions found in and around pulsars make them fantastic natural laboratories, providing insights to a rich variety of fundamental physics and astronomy. To discover more pulsars we have begun the High Time Resolution Universe (HTRU) survey: a blind survey of the northern sky with the 100-m Effelsberg radio telescope in Germany and a twin survey of the southern sky with the 64-m Parkes radio telescope in Australia. The HTRU is an international collaboration with expertise shared among the MPIfR in Germany, ATNF/CASS and Swinburne University of Technology in Australia, University of Manchester in the UK and INAF in Italy. The HTRU survey uses multi-beam receivers and backends constructed with recent advancements in technology, providing unprecedentedly high time and frequency resolution, allowing us to probe deeper into the Galaxy than ever before. While a general overview of HTRU has been given by Keith at this conference, here we focus on three further aspects of HTRU discoveries and highlights. These include the ‘Diamond-planet pulsar’ binary J1719-1438 and a second similar system recently discovered. In addition, we provide specifications of the HTRU-North survey and an update of its status. In the last section we give an overview of the search for highly-accelerated binaries in the Galactic plane region. We discuss the computational challenges arising from the processing of the petabyte-sized HTRU survey data. We present an innovative segmented search technique which aims to increase our chances of discovering highly accelerated relativistic binary systems, potentially including pulsar-black-hole binaries.

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