English
Related papers

Related papers: The latest results from the Global mm-VLBI Array

200 papers

We present continent-scale VLBI - obtained with the European VLBI Network (EVN) at a wavelength of 18cm - of six distant, luminous submm-selected galaxies (SMGs). Our images have a synthesized beam width of ~30 milliarcsec FWHM - three…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 A. D. Biggs , J. D. Younger , R. J. Ivison

We are leading a comprehensive multi-waveband monitoring program of 34 gamma-ray bright blazars designed to locate the emission regions of blazars from radio to gamma-ray frequencies. The "maps" are anchored by sequences of images in both…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Alan Marscher , Svetlana G. Jorstad , Valeri M. Larionov , Margo F. Aller , Anne Lahteenmaki

The ngVLA is a new interferometric radio astronomy facility with transformative capabilities, being developed by the National Radio Astronomy Observatory. It combines two orders of magnitude in frequency coverage, over 1.2 - 116 GHz, with…

Instrumentation and Methods for Astrophysics · Physics 2025-04-22 T. K. Sridharan , S. Bhatnagar , P. Jagannathan , K. Golap

We discuss the technique of Wide-field imaging as it applies to Very Long Baseline Interferometry (VLBI). In the past VLBI data sets were usually averaged so severely that the field-of-view was typically restricted to regions extending a…

Astrophysics · Physics 2009-10-31 M. A. Garrett , R. W. Porcas , A. Pedlar , T. W. B. Muxlow , S. T. Garrington

The generalized maximum entropy method (GMEM) is a special modification of the standard maximum entropy method (MEM) which seeks solutions in the space of complex functions. In this work a reduced version of the GMEM intended for…

Astrophysics · Physics 2015-06-24 Anisa T. Bajkova

Ever since the discovery by the Fermi mission that active galactic nuclei (AGN) produce copious amounts of high-energy emission, its origin has remained elusive. Using high-frequency radio interferometry (VLBI) polarization imaging, we…

High Energy Astrophysical Phenomena · Physics 2018-05-15 B. Rani , S. G. Jorstad , A. P. Marscher

An international consortium is presently constructing a beamformer for the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile that will be available as a facility instrument. The beamformer will aggregate the entire collecting…

Very long baseline interferometry (VLBI) makes it possible to recover images of astronomical sources with extremely high angular resolution. Most recently, the Event Horizon Telescope (EHT) has extended VLBI to short millimeter wavelengths…

Instrumentation and Methods for Astrophysics · Physics 2018-02-05 Katherine L. Bouman , Michael D. Johnson , Adrian V. Dalca , Andrew A. Chael , Freek Roelofs , Sheperd S. Doeleman , William T. Freeman

The Atacama Large Millimeter/submillimeter Array remains the largest mm radio interferometer observatory world-wide. It is now conducting its 11th observing cycle. In our previous paper presented at this conference series in 2020, we…

Instrumentation and Methods for Astrophysics · Physics 2024-08-09 Dirk Petry , María Díaz Trigo , Rüdiger Kneissl , Ignacio Toledo , Atsushi Miyazaki , Toshinobu Takagi , Ashley Barnes , Francesca Bonanomi

Millimetre-VLBI is an important tool in AGN astrophysics, but it is limited by short atmospheric coherence times and poor receiver and antenna performance. We demonstrate a new kind of phase referencing for the VLBA, enabling us to increase…

Astrophysics · Physics 2007-05-23 E. Middelberg , A. L. Roy , R. C. Walker , H. Falcke , T. P. Krichbaum

The European VLBI Network is a collaboration of the major radio astronomical institutes in Europe, Asia, South Africa and Puerto Rico. Established four decades ago, since then it has constantly improved its performance in terms made using…

Instrumentation and Methods for Astrophysics · Physics 2015-01-22 J. A. Zensus , E. Ros

The Very Large Array (VLA) Low-frequency Sky Survey (VLSS) has imaged 95% of the 3*pi sr of sky north of declination = -30 degrees at a frequency of 74 MHz (4 meter wavelength). The resolution is 80" (FWHM) throughout, and the typical RMS…

Very Long Baseline Interferometry (VLBI) combines the signals of telescopes distributed across thousands of kilometres to provide some of the highest angular resolution images of astrophysical phenomena. Due to computational expense,…

Instrumentation and Methods for Astrophysics · Physics 2025-04-30 Jack F. Radcliffe , J. P. McKean , C. Herbé-George , L. Coetzer , T. Matsepane

Simultaneous observations at multiple frequency bands have the potential to overcome the fundamental limitation imposed by the atmospheric propagation in mm-VLBI observations. The propagation effects place a severe limit in the sensitivity…

Instrumentation and Methods for Astrophysics · Physics 2015-12-23 Maria J. Rioja , Richard Dodson , Taehyun Jung , Bong Won Sohn

The Korean VLBI Network (KVN) is a new mm-VLBI dedicated array with capability for simultaneous observations at multiple frequencies, up to 129 GHz. The innovative multi-channel receivers present significant benefits for astrometric…

In this paper, we conduct a multi-frequency analysis of the gamma-ray bright blazar 1308+326 from February 2013 to March 2020, using the Korean VLBI Network at 22 and 43 GHz and gamma-ray data from the Fermi Large Area Telescope (LAT). Our…

High Energy Astrophysical Phenomena · Physics 2024-04-12 Shan Li , Sang-Sung Lee , Whee Yeon Cheong

We report on recent technical developments in the front- and back-ends for the four 20 m radio telescopes of the Japanese Very-Long-Baseline Interferometry (VLBI) project, VLBI Exploration of Radio Astrometry (VERA). We present a brief…

Instrumentation and Methods for Astrophysics · Physics 2022-12-21 Yoshiaki Hagiwara , Kazuhiro Hada , Mieko Takamura , Tomoaki Oyama , Aya Yamauchi , Syunsaku Suzuki

Context. Blazars are among the most energetic objects in the Universe. In 2008 August, Fermi/LAT detected the blazar PKS 1502+106 showing a rapid and strong gamma-ray outburst followed by high and variable flux over the next months. This…

High Energy Astrophysical Phenomena · Physics 2016-01-27 V. Karamanavis , L. Fuhrmann , T. P. Krichbaum , E. Angelakis , J. Hodgson , I. Nestoras , I. Myserlis , J. A. Zensus , A. Sievers , S. Ciprini

The Fermi Gamma-ray Space Telescope, as an all-sky survey and monitoring mission, is producing daily/weekly sampled gamma-ray light curves for dozens of blazars and other high-energy sources. Highlights on MeV-GeV gamma-ray variability…

High Energy Astrophysical Phenomena · Physics 2011-12-13 Stefano Ciprini