We introduce a new space VLBI project, the Second VLBI Space Observatory Program (VSOP2), following the success of the VLBI Space Observatory Program (VSOP1). VSOP2 has 10 times higher angular resolution, up to about 40 micro arcseconds, 10 times higher frequency up to 43 GHz, and 10 times higher sensitivity compared to VSOP1. Then VSOP2 should become a most powerful tool to observe innermost r...

Recent millimeter-VLBI observations of Sagittarius A* (Sgr A*) have, for the first time, directly probed distances comparable to the horizon scale of a black hole. This provides unprecedented access to the environment immediately around the horizon of an accreting black hole. We leverage both existing spectral and polarization measurements and our present understanding of accretion theory to pr...

The GLT project is deploying a new submillimeter (submm) VLBI station in Greenland. Our primary scientific goal is to image a shadow of the supermassive black hole (SMBH) of six billion solar masses in M87 at the center of the Virgo cluster of galaxies. The expected SMBH shadow size of 40-50 μas requires superbly high angular resolution, suggesting that the submm VLBI would be the only way to o...

As the shock and expanding shell of a supernova plow out through the circumstellar material at thousands of km s −1 , radio emission is generated. VLBI observations of this radio emission are presently the only means to directly image the expanding shell of any supernova much farther away than SN 1987A. The last decade has seen great progress in VLBI imaging of radio supernovae. In particular, ...

Here we report on the VLBI discovery of solar-like extended streamers anchored on the two weak-line T Tauri stars of the binary system V773 Tau A. Covering the interbinary distance the ∼ 20 stellar radii extended streamers enter in collision during each stellar rotation with consequent occurrence of magnetic reconnection. Thermal electrons confined in the streamers become accelerated to relativ...

We 1 summarize previous VLBI observations of Sgr A* at millimeter wavelengths and present new results from VLBI observations at 86 GHz and at 215 GHz. At 86 GHz the measured closure phase is close to zero, consistent with a point-like or symmetric structure of 190±30 µas size. At 215 GHz we have (for the first time) detected Sgr A* with a signal-to-noise ratio of 6. This yields a tentative size...

Global millimetre VLBI allows detailed studies of the most central jet regions of AGN with unprecedent spatial resolution of a few 100–1000 Schwartzschild radii to be made. Study of these regions will help to answer the question how the highly relativistic AGN jets are launched and collimated. Since the early 1990s, bright mm-sources have been observed with global 3 mm VLBI. Here we present new...

86 GHz Very Long Baseline Polarimetry probes magnetic field structures within the cores of Active Galactic Nuclei at higher angular resolutions and a spectral octave higher than previously achievable. Observations of 3C 273 and 3C 279 taken in April 2000 with the Coordinated Millimeter VLBI Array have resulted in the first total intensity (Stokes I) and linear polarization VLBI images reported ...

The high radio frequency polarization imaging of non-thermal emission from active galactic nuclei (AGN) is a direct way to probe the magnetic field strength and structure in the immediate vicinity of supermassive black holes (SMBHs) and is crucial in testing the jet-launching scenario. To explore the the magnetic field configuration at the base of jets in blazars, we took advantage of the full ...