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The huge potential of VLBI at submm/mm wavelengths is that it enables the highest resolution imaging currently possible at any wavelength in astronomy. Using ALMA as a phased array to form part of a global VLBI network will offer unprecedented sensitivity at very high angular resolution, making one order of magnitude weaker sources accessible to μas-resolution studies and greatly improving image fidelity for the brighter objects . Moreover, it will allow the shadow of a black hole, test of general relativity near black holes, investigate jet launch and collimation from AGN and microquasars, pulsar and magnetar emission processes, the chemical history of the universe and the evolution of fundamental constants across cosmic time, maser science, and astrometry.


VLBI inherently requires many telescopes to operate together. Existing activities at 3 mm (the Very Long Baseline Array and the Global Millimeter VLBI Array) and at 1 mm (the Event Horizon Telescope project) have laid the ground work for future coordinated observations. An international consortium is presently constructing a beamformer for the ALMA that will be available as a facility instrument providing substantial improvements to existing VLBI arrays in Bands 1 and 3 (7 and 3 mm).

Nov 2012: the Alma Phasing Project has successfully passed its preliminary design review.

2015: initial ALMA phasing tests.

2016: first ALMA phasing observations

2019 April 10th: first image of a black hole with EHT (including ALMA)

Italian ARC contribution

We start to get involved in mm-VLBI with ALMA from 2013, making use of our extensive in-house experience with (radio frequency) VLBI. From January 2018, we are members of the BlackHoleCam and Event Horizon Telescope Consortium where we are contributing in

  • Calibration and Error working group developing an innovative CASA pipeline for the data reduction of EHT (and VLBI in general) observations.
  • Time Domain analysis working group to reveal possible periodicities in the data.

The 2019 April 10th we took part at the EHT press release of the first image of a black hole organizing the national press conference in Rome.

In the following months, we were invited at several conferences and tv interviews to present the groundbreaking EHT results which direct confirm for the first time the validity of the general relativity theory in extreme gravitational field.

Work is now focusing to provide the first movie of a black hole which will give important information on how the material is falling into the central massive black hole.

Related publications:

EHT related papers

From ADS (last update 2020 Jan 23rd)

White papers

  • High-Angular-Resolution and High-Sensitivity Science Enabled by Beamformed ALMA, Fish et al. 2013, arXiv:1309.3519.

  • Future mmVLBI Research with ALMA: A European vision, Tilanus et al. 2014

ESO Upgrade Proposal

Phased ALMA as an Element of the Global Millimetre VLBI Array, August 2013

Contact persons

Elisabetta Liuzzo, Kazi Rygl, Nicola Marchili, Marcella Massrdi

Related links

The Global Millimeter Array (GMVA)

Event Horizon Telescope