Karl G. Jansky Very Large Array

Résumé

Le Karl G. Jansky Very Large Array (le « Très grand réseau Karl-G.-Jansky »), à l'origine le Very Large Array ou VLA (le « Très grand réseau »), est un radiotélescope situé dans la plaine de San Augustin au Nouveau-Mexique (États-Unis). Rattaché au National Radio Astronomy Observatory, il est formé de paraboliques identiques, larges de chacune, qui se déplacent sur des voies de chemin de fer disposées selon un tracé formant un immense Y (deux branches de et un pied de ). Les ont chacune leur propre récepteur, les signaux de chaque récepteur étant transmis à un site central où ils sont combinés : l'image haute résolution ainsi obtenue équivaut à celle d'un très grand radiotélescope, dont le diamètre serait égal à la distance maximale séparant les antennes. La résolution angulaire maximale pouvant être atteinte est d'environ d'arc. Le Very Large Array a été rebaptisé du nom de Karl Jansky en , à la suite du vote d'internautes. Filmographie

2010 : L'Année du premier

Source officielle

https://fr.wikipedia.org/wiki/Karl_G._Jansky_Very_Large_Array

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The e-MERGE Survey (e-MERLIN Galaxy Evolution Survey): overview and survey description

Jean-Paul Richard Kneib, Mark Thomas Sargent, Cole Stewart Simpson

We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising similar to 140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and similar to 40 h with the Very Large Array (VLA). We combine the long baselines of e-MERLIN (providing high angular resolution) with the relatively closely packed antennas of the VLA (providing excellent surface brightness sensitivity) to produce a deep 1.5-GHz radio survey with the sensitivity (similar to 1.5 mu Jy beam(-1)), angular resolution (0.2-0.7 arcsec) and field-of-view (similar to 15x15 arcmin(2)) to detect and spatially resolve star-forming galaxies and active galactic nucleus (AGN) at z greater than or similar to 1. The goal of e-MERGE is to provide new constraints on the deep, sub-arcsecond radio sky which will be surveyed by SKA1-mid. In this initial publication, we discuss our data analysis techniques, including steps taken to model in-beam source variability over an similar to 20-yr baseline and the development of newpoint spread function/primary beam models to seamlessly merge e-MERLIN and VLA data in the uv plane. We present early science results, including measurements of the luminosities and/or linear sizes of similar to 500 galaxies selected at 1.5 GHz. In combination with deep Hubble Space Telescope observations, we measure a mean radio-to-optical size ratio of r(e-MERGE)/r(HST) similar to 1.02 +/- 0.03, suggesting that in most high-redshift galaxies, the similar to GHz continuum emission traces the stellar light seen in optical imaging. This is the first in a series of papers that will explore the similar to kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e-MERGE DR1.

OXFORD UNIV PRESS2020

Chargement

We report broadband spin-wave spectroscopy on kagome artificial spin ices (KASIs) made of large arrays of disconnected Ni81Fe19 400-nm-long nanobars. We observed spin wave spectra that varied characteristically upon the separation between neighboring nanobars. The dipolar coupling within the KASI is analyzed in terms of a configuration-dependent bias field. It varies between about 30 and 40 mT for nearest-neighbor separations of 300 and 60 nm, respectively. Similarly to interconnected KASIs, we reprogram the spin wave spectra by means of a specific field protocol. The disconnected KASIs are promising for reprogramable spin wave guiding in underlayers.

2021

Chargement

Angle-dependent magnetization dynamics with mirror-symmetric excitations in artificial quasicrystalline nanomagnet lattices

Vinayak Shantaram Bhat, Dirk Grundler

We report angle-dependent spin-wave spectroscopy on aperiodic quasicrystalline magnetic lattices, i.e., Ammann, Penrose P2 and P3 lattices made of large arrays of interconnected Ni80Fe20 nanobars. Spin-wave spectra obtained in the nearly saturated state contain distinct sets of resonances with characteristic angular dependencies for applied in-plane magnetic fields. Micromagnetic simulations allow us to attribute detected resonances to mode profiles with specific mirror symmetries. Spectra in the reversal regime show systematic emergence and disappearance of spin-wave modes indicating reprogrammable magnonic characteristics.

2018

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The e-MERGE Survey (e-MERLIN Galaxy Evolution Survey): overview and survey description

Jean-Paul Richard Kneib, Mark Thomas Sargent, Cole Stewart Simpson

OXFORD UNIV PRESS2020