High fidelity spectroscopic imaging at low radio frequencies to estimate plasma parameters of solar coronal mass ejections at higher coronal heights

2021 ◽  
Author(s):  
Devojyoti Kansabanik ◽  
Surajit Mondal ◽  
Divya Oberoi ◽  
Angelos Vourlidas
Keyword(s):  
Radio Emission ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Physical Parameters ◽  
Plasma Parameters ◽  
Radio Imaging ◽  
Gyrosynchrotron Emission ◽  
Murchison Widefield Array

<p>Coronal Mass Ejections (CMEs) are large-scale explosive eruptions of magnetised plasma from the Sun into the Heliosphere. Measuring the physical parameters of CMEs is crucial for understanding their physics and for assessing their geo-effectiveness. Radio observations offer the most direct means for estimating these plasma parameters when gyrosynchrotron (GS) emission is detected from the CME plasma. However, since the first detection by Bastian et al.2001, only a handful of studies have successfully detected GS emission from CME plasma. This is usually attributed to the challenges involved in obtaining the high dynamic range imaging required for observing this faint gyrosynchrotron emission in the vicinity of active solar emissions.</p><p>The newly developed imaging pipeline (Mondal et al., 2019) designed for the data from Murchison Widefield Array (MWA) marks a significant improvement in metrewave solar radio imaging. Our work suggests that we should now be able to routinely detect GS emission from CME plasma. We present an example where we have successfully detected radio emission from CME plasma and modelled it as GS emission, leading to reliable estimates of CME magnetic field as well as the distribution of energetic electrons (Mondal et al. 2020). In a different example we are able to detect the radio emission from the CME plasma out to as far as 8.3 solar radii. We find that the observed spectra are not always consistent with simple GS models. This highlights that more complicated physics might be at play and points to the need for building more detailed models for interpreting these emissions. We hope that with the availability of polarimetric imaging capability, which we are in the process of developing, this technique will provide a robust way to routinely measure CME magnetic fields along with its other physical parameters. We note that these are the weakest detections of GS emissions from CME plasma reported yet.</p>

scholarly journals Modular operation of microfluidic chips for highly parallelized cell culture and liquid dosing via a fluidic circuit board

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
A. R. Vollertsen ◽  
D. de Boer ◽  
S. Dekker ◽  
B. A. M. Wesselink ◽  
R. Haverkate ◽  
...  
Keyword(s):  
Cell Culture ◽  
Large Scale ◽  
Dynamic Range ◽  
Umbilical Vein ◽  
Building Blocks ◽  
High Dynamic Range ◽  
Microfluidic System ◽  
Circuit Board ◽  
Microfluidic Chips ◽  
Umbilical Vein Endothelial Cells

AbstractMicrofluidic systems enable automated and highly parallelized cell culture with low volumes and defined liquid dosing. To achieve this, systems typically integrate all functions into a single, monolithic device as a “one size fits all” solution. However, this approach limits the end users’ (re)design flexibility and complicates the addition of new functions to the system. To address this challenge, we propose and demonstrate a modular and standardized plug-and-play fluidic circuit board (FCB) for operating microfluidic building blocks (MFBBs), whereby both the FCB and the MFBBs contain integrated valves. A single FCB can parallelize up to three MFBBs of the same design or operate MFBBs with entirely different architectures. The operation of the MFBBs through the FCB is fully automated and does not incur the cost of an extra external footprint. We use this modular platform to control three microfluidic large-scale integration (mLSI) MFBBs, each of which features 64 microchambers suitable for cell culturing with high spatiotemporal control. We show as a proof of principle that we can culture human umbilical vein endothelial cells (HUVECs) for multiple days in the chambers of this MFBB. Moreover, we also use the same FCB to control an MFBB for liquid dosing with a high dynamic range. Our results demonstrate that MFBBs with different designs can be controlled and combined on a single FCB. Our novel modular approach to operating an automated microfluidic system for parallelized cell culture will enable greater experimental flexibility and facilitate the cooperation of different chips from different labs.

scholarly journals The Sun at the VLA's Metric and Decimetric Wavelengths

1990 ◽  
Vol 142 ◽  
pp. 523-524
Author(s):  
S. M. White ◽  
M. R. Kundu ◽  
N. Gopalswamy ◽  
E. J. Schmahl
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Active Regions ◽  
High Dynamic Range ◽  
The Sun ◽  
Large Array ◽  
Very Large Array ◽  
Preliminary Results ◽  
High Dynamic ◽  
Coronal Structures

During September 1988 (International Solar Month) we observed the Sun with the Very Large Array on 4 days in the period Sep. 11-17. The VLA was in its most compact configuration, which is ideal for studying large-scale coronal structures. Here we summarize some preliminary results of the observations at 0.333 and 1.5 GHz. Despite the presence of numerous active regions the Sun was actually very quiet, with no flares during our observing, and this allowed us to make high-dynamic-range maps.

A calibration and imaging strategy at 300 MHz with the Murchison Widefield Array (MWA)

2021 ◽  
Vol 38 ◽  
Author(s):  
Jaiden H. Cook ◽  
Nicholas Seymour ◽  
Marcin Sokolowski
Keyword(s):  
Dynamic Range ◽  
Low Frequency ◽  
High Dynamic Range ◽  
Primary Beam ◽  
Main Lobe ◽  
Beam Model ◽  
Highly Sensitive ◽  
Imaging Strategy ◽  
Murchison Widefield Array ◽  
Beam Patterns

Abstract At relatively high frequencies, highly sensitive grating sidelobes occur in the primary beam patterns of low frequency aperture arrays (LFAA) such as the Murchison Widefield Array (MWA). This occurs when the observing wavelength becomes comparable to the dipole separation for LFAA tiles, which for the MWA occurs at ${\sim}300$ MHz. The presence of these grating sidelobes has made calibration and image processing for 300 MHz MWA observations difficult. This work presents a new calibration and imaging strategy which employs existing techniques to process two example 300 MHz MWA observations. Observations are initially calibrated using a new 300 MHz sky-model which has been interpolated from low frequency and high frequency all-sky surveys. Using this 300 MHz model in conjunction with the accurate MWA tile primary beam model, we perform sky-model calibration for the two example observations. After initial calibration a self-calibration loop is performed by all-sky imaging each observation. We mask the main lobe of the all-sky image, and perform a sky-subtraction by estimating the masked image visibilities. We then image the main lobe of the sky-subtracted visibilities, which results in high dynamic range images of the two example observations. These images have been convolved with a Gaussian to a resolution of $2.4$ arcminutes, with a maximum sensitivity of ${{\sim}}31\,\textrm{mJy/beam}$ . The calibration and imaging strategy demonstrated in this work opens the door to performing science at 300 MHz with the MWA, which was previously an inaccessible domain. With this paper we release the code described below and the cross-matched catalogue along with the code to produce a sky-model in the range 70–1 400 MHz.

The Anza array: A high-dynamic-range, broadband, digitally radiotelemetered seismic array

1984 ◽  
Vol 74 (4) ◽  
pp. 1469-1481
Author(s):  
Jon Berger ◽  
L. M. Baker ◽  
J. N. Brune ◽  
J. B. Fletcher ◽  
T. C. Hanks ◽  
...  
Keyword(s):  
Large Scale ◽  
Scaling Laws ◽  
Dynamic Range ◽  
Body Wave ◽  
Sampling Rate ◽  
Digital Transmission ◽  
High Dynamic Range ◽  
Seismic Array ◽  
High Rate ◽  
Small Aperture

Abstract A small aperture seismic array has been deployed along a 30-km stretch of the San Jacinto fault in the vicinity of the town of Anza, California. The array was installed to study specifically the scaling laws of body-wave spectra, the character of high-frequency ground motion, the physical interpretation of seismic stress drops, and the interaction of earthquakes. This region was chosen for these studies due to its high rate of seismic activity in the 2 ≦ M ≦ 4.5 range, the likelihood of a M > 6 event in the next decade, and the existence of the Southern California Batholith on either side of the fault, reducing problems associated with attenuation and large scale anisotropy. These studies employ an instrument package with a frequency response of 100 Hz, a dynamic range of 138 dB, a sampling rate of 250 times per second per component, and a 16-bit A/D converter. The array consists of 10 three-component stations, telemetered via digital VHF radio to a nearby mountain peak and thence via a microwave link to La Jolla, California. A minicomputer system monitors the array's performance, detects events, and records data upon demand. Initial results demonstrate the feasibility of digital transmission with an inherent increase in data quality over analog systems.

85-1: Visually Lossless Compression of High Dynamic Range Images: A Large-Scale Evaluation

2018 ◽  
Vol 49 (1) ◽  
pp. 1151-1154 ◽  
Author(s):  
Aishwarya Sudhama ◽  
Matthew D. Cutone ◽  
Yuqian Hou ◽  
James Goel ◽  
Dale Stolitzka ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Lossless Compression ◽  
High Dynamic Range ◽  
Range Images ◽  
Scale Evaluation ◽  
High Dynamic

scholarly journals DAYENU: a simple filter of smooth foregrounds for intensity mapping power spectra

2020 ◽  
Vol 500 (4) ◽  
pp. 5195-5213
Author(s):  
Aaron Ewall-Wice ◽  
Nicholas Kern ◽  
Joshua S Dillon ◽  
Adrian Liu ◽  
Aaron Parsons ◽  
...  
Keyword(s):  
Large Scale ◽  
Dynamic Range ◽  
Fourier Transforms ◽  
Power Spectra ◽  
High Dynamic Range ◽  
Spectrum Estimation ◽  
Sampled Data ◽  
Optimal Basis ◽  
Intensity Mapping ◽  
Band Limited

ABSTRACT We introduce DPSS Approximate lazY filtEriNg of foregroUnds (dayenu), a linear, spectral filter for H i intensity mapping that achieves the desirable foreground mitigation and error minimization properties of inverse co-variance weighting with minimal modelling of the underlying data. Beyond 21-cm power-spectrum estimation, our filter is suitable for any analysis where high dynamic-range removal of spectrally smooth foregrounds in irregularly (or regularly) sampled data is required, something required by many other intensity mapping techniques. Our filtering matrix is diagonalized by Discrete Prolate Spheroidal Sequences which are an optimal basis to model band-limited foregrounds in 21-cm intensity mapping experiments in the sense that they maximally concentrate power within a finite region of Fourier space. We show that dayenu enables the access of large-scale line-of-sight modes that are inaccessible to tapered discrete Fourier transform estimators. Since these modes have the largest SNRs,dayenu significantly increases the sensitivity of 21-cm analyses over tapered Fourier transforms. Slight modifications allow us to use dayenu as a linear replacement for iterative delay clean ing (dayenurest). We refer readers to the Code section at the end of this paper for links to examples and code.

scholarly journals Australian square kilometre array pathfinder: I. system description

2021 ◽  
Vol 38 ◽  
Author(s):  
A. W. Hotan ◽  
J. D. Bunton ◽  
A. P. Chippendale ◽  
M. Whiting ◽  
J. Tuthill ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Radio Telescopes ◽  
System Description ◽  
Square Kilometre Array ◽  
Science Operations ◽  
High Dynamic ◽  
Radio Transients

Abstract In this paper, we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers $31\,\textrm{deg}^{2}$ at $800\,\textrm{MHz}$ . As a two-dimensional array of 36 $\times$ 12 m antennas, with baselines ranging from 22 m to 6 km, ASKAP also has excellent snapshot imaging capability and 10 arcsec resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 and $1800\,\textrm{MHz}$ and is expected to facilitate great advances in our understanding of galaxy formation, cosmology, and radio transients while opening new parameter space for discovery of the unknown.

scholarly journals The radio/gamma-ray connection from 120 MHz to 230 GHz

2016 ◽  
Author(s):  
Marcello Giroletti ◽  
Filippo D'Ammando ◽  
Monica Orienti ◽  
Rocco Lico
Keyword(s):  
Radio Emission ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Low Frequency ◽  
High Energy ◽  
Physical Parameters ◽  
Radiation Emission ◽  
Spatial Features ◽  
Murchison Widefield Array ◽  
Radio Band

Radio loud active galactic nuclei are composed of different spatial features, each one characterized by different spectral properties in the radio band. Among them, blazars are the most common class of sources detected at gamma-rays by \fermi, and their radio emission is dominated by the flat spectrum compact core. In this contribution, we explore the connection between emission at high energy revealed by \fermi\ and at radio frequency. Taking as a reference the strong and very highly significant correlation found between gamma rays and cm-$\lambda$ radio emission, we explore different behaviours found as we change the energy range in gamma rays and in radio, therefore changing the physical parameters of the zones involved in the radiation emission. We find that the correlation weakens when we consider (1) gamma rays of energy above 10 GeV (except for high synchrotron peaked blazars) or (2) low frequency radio data taken by the Murchison Widefield Array; on the other hand, the correlation strengthens when we consider mm-$\lambda$ data taken by ALMA.

scholarly journals BAT AGN spectroscopic survey - XV: the high frequency radio cores of ultra-hard X-ray selected AGN

2020 ◽  
Vol 492 (3) ◽  
pp. 4216-4234 ◽  
Author(s):  
Krista Lynne Smith ◽  
Richard F Mushotzky ◽  
Michael Koss ◽  
Benny Trakhtenbrot ◽  
Claudio Ricci ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Radio Emission ◽  
High Frequency ◽  
Physical Parameters ◽  
X Ray ◽  
Radio Imaging ◽  
Significant Difference ◽  
The Relationship ◽  
Radio Power

ABSTRACT We have conducted 22 GHz radio imaging at 1 arcsec resolution of 100 low-redshift AGN selected at 14–195 keV by the Swift-BAT. We find a radio core detection fraction of 96 per cent, much higher than lower frequency radio surveys. Of the 96 radio-detected AGN, 55 have compact morphologies, 30 have morphologies consistent with nuclear star formation, and 11 have sub-kpc to kpc-scale jets. We find that the total radio power does not distinguish between nuclear star formation and jets as the origin of the radio emission. For 87 objects, we use optical spectroscopy to test whether AGN physical parameters are distinct between radio morphological types. We find that X-ray luminosities tend to be higher if the 22 GHz morphology is jet-like, but find no significant difference in other physical parameters. We find that the relationship between the X-ray and core radio luminosities is consistent with the LR/LX ∼ 10−5 of coronally active stars. We further find that the canonical fundamental planes of black hole activity systematically overpredict our radio luminosities, particularly for objects with star formation morphologies.

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