The South African Radio Astronomy Observatory (SARAO) is a national facility that is responsible for radio astronomy research and infrastructure development in South Africa. It manages key projects such as the MeerKAT telescope which is a precursor to the Square Kilometre Array (SKA)-mid telescope. The Receivers Team at SARAO is primarily responsible for the production of Digitsers units for...
In this report, we present our recent study of the acceleration and collimation of the two-sided jets in the nearby low-luminosity AGN NGC 4261. We robustly identify a parabolic-to-conical structural transition in both the jet and counterjet, with the transition occurring on (sub)parsec scales. Based on the jet-to-counterjet brightness, we derive the jet velocity field at distances of ∼ (10^3...
In this report, we present our recent study of the acceleration and collimation of the two-sided jets in the nearby low-luminosity AGN NGC 4261. We robustly identify a parabolic-to-conical structural transition in both the jet and counterjet, with the transition occurring on (sub)parsec scales. Based on the jet-to-counterjet brightness, we derive the jet velocity field at distances of ∼ (10^3...
Gravitational lensing is one of the most powerful tools to investigate the dark Universe (dark energy via gravitational time delays and dark matter (via low mass lenses). Nevertheless, these fundamental cosmological studies are limited by the paucity of lensing systems known to date. Finding novel and effective ways to identify strong lenses represent, therefore, a new challenge that has to be...
In this talk, we will briefly introduce recent FPT/SFPR-related activities with the M2FINDERS project, which aims at mapping the magnetic field at the event horizon scale of SMBHs.
First, a recent single-baseline test between APEX and IRAM 30-m RT has successfully demonstrated the FPT method up to 258 GHz, which extends the 258 GHz coherence time from 10 seconds to ~ 1 minute (90% coherence...
This talk summarizes our progress of our HINOTORI (Hybrid Integration Project in Nobeyama, Triple-band Oriented) since 2016, which now enables us to simultaneously observe in 22/43/86-GHz bands in single-dish mode. The HINOTORI system just employs combination of perforated frequency-band selection filter plates installed in the quasi-optics of the Nobeyama 45 m radio telescope with the...
The Thai National Radio Astronomy Observatory (TNRO), established in Chiang Mai in 2017 by the National Astronomical Research Institute of Thailand (NARIT, Public Organization), advances radio astronomy and geodesy infrastructure in Thailand. Its centerpiece, the 40-meter Thai National Radio Telescope (TNRT) that is designed as an enhanced version of the 40-meter Yebes Radio Telescope,...
The launching mechanism of jets remains one of the fundamental challenges in astrophysics. We are presently carrying on a campaign of 22 GHz water maser VLBI observations to prove on a robust statistical ground that magnetohydrodynamic disk winds represent the common launching mechanism of protostellar jets. Several methanol maser transitions can provide complementary information to the 22 GHz...
The Global Millimetre VLBI Array (GMVA) is a high-sensitivity global millimetre VLBI instrument that operates at wavelengths of 3 mm and 7 mm. Recent enhancements, such as the inclusion of phased ALMA and the upgrade of the NOEMA observatory, have significantly improved the array’s sensitivity and imaging capabilities. The GMVA now plays a central role in enabling high-resolution studies of...
Simultaneous multi-band receiving system enables the detection of weak targets with mm-VLBI through the frequency phase transfer (FPT) or source-frequency phase-referencing (SFPR) technique. This provides great advantages both for imaging and astrometry. In this talk, I will report some observations with SFPR on weak targets including supermassive black holes and binaries. We successfully...
The African Millimeter Telescope (AMT) is now poised to become a reality in less than half-a-decade. In anticipation of the arrival of the AMT, a number of simulations have been carried out to explore the possible improvement in UV-coverage of various VLBI networks and the Event Horizon Project. In this talk, I will present some of the results of the simulations to show the significant impact...
We present new VLBI results on PKS 1540−077, a GHz-Peaked Spectrum (GPS) source and a strong candidate for a parsec-scale dual supermassive black hole (SMBH) system. Previous VLBA observations at 5 and 8 GHz revealed two compact, flat-spectrum components separated by ~130 pc, with no significant relative motion, inconsistent with typical jet dynamics. Our recent 22 GHz EAVN observation...
Abstract: As a part of a major infrastructure upgrade, Aalto
University Metsähovi Radio Observatory will renew the receivers and
data acquisition systems of its 14-metre radio telescope. A key part
of this upgrade is a new ultra-wide-bandwidth triple-band receiver
that is able to simultaneously observe at 18-26, 34-50 and 80-116
GHz. The dual-beam, gain-stabilized receiver will have more...
The K-Q-W band receiver, a crucial component for advanced radio astronomy observations, was successfully delivered at the end of 2022. This acquisition was made possible through funding from the Ministry of Research, as part of the PON "Innovation 20-24" program. Upon the definition of the receiver's operational requirements (first stages of PON project), a comprehensive plan was initiated to...
Very long baseline interferometry (VLBI) observations provide high sensitivity and high resolution, allowing us to resolve relativistic jets from active galactic nuclei (AGNs) into several knot-like features. In addition, spectral analysis of such resolved plasma populations can be performed when combined with (quasi-)simultaneous multi-frequency observations. In particular, high-frequency...
Direct detection of supermassive black hole binaries (SMBHBs)—via resolved imaging of dual sources and precise orbital tracking—demands extreme astrometric precision (~1 μas/yr). Linking SMBHB evolution (from ≲10 kpc dynamical friction to ≲0.01 pc gravitational-wave stages) with observational capabilities, we estimate detectability: For AGNs with 5% SMBHB occurrence, a 86 GHz VLBI system...
The discovery of high-energy TeV/PeV neutrinos (HENs) by the IceCube Neutrino Observatory has motivated extensive efforts to identify their astrophysical origins. Blazars, a subclass of active galactic nuclei with relativistic jets aimed toward Earth, have emerged as promising HEN candidates, especially after the association of a HEN event with the blazar TXS 0506+056. However, the origin of...
Thanks to their ability to escape dense astrophysical environments and their straight-line propagation over cosmological distances, neutrinos provide a unique probe of the high-energy Universe. Neutrino astronomy, initiated by pioneering experiments such as ANTARES and IceCube, is now evolving rapidly, with a new generation of detectors coming into play.
Among these, KM3NeT is expected to...
This study explores the scientific motivation and feasibility of observing water megamasers at 183 GHz using VLBI techniques. To date, more than a dozen extragalactic 183 GHz megamasers have been detected, with a high detection rate achieved through ALMA observations targeting known 22 GHz megamaser sources. Compared to the 22 GHz masers,
183 GHz millimeter-wave megamasers suffer less...
Astrometry at the very highest of frequencies is an unexplored frontier for VLBI observations. Astrometry is equally vital to connect observations at different times and different frequencies. The former is used for measuring proper motions and parallaxes to derive distances to the targets - and thus their physical characteristics.
The latter is to reference two images at different...
With the recent and ongoing upgrades of the VLBI INAF antennas of Medicina (Bologna) and Noto (Siracusa), together with the implementation of the Compact Tri-band Korean Receivers, all the Italian facilities, including the Sardinia Radio Telescope (SRT), are ready for performing millimeter-wave observations up to W-band (about 110 GHz). Because of the receiver bands available, around 18 GHz,...
We present the sub-pc scale molecular absorption studies in the circumnuclear region of the radio galaxy NGC 1052. Utilizing the KVN multi-frequency receiving system and the FPT technique, our KVN observations at mm bands spatially have resolved the molecular absorptions against a two-sided nuclear structure. The absorbing molecular clouds are concentrated on the receding jet and the nuclear...
The Tianma Telescope is currently developing a K/Q/W triple-band cryogenic receiver. The entire system comprises a microwave quasi-optical system, a cryogenic electronics unit, a warm frequency conversion unit, and a power & control unit. The microwave quasi-optical system is being developed in collaboration with Osaka Metropolitan University (OMU) in Japan. OMU is responsible for the...
The blazar 3C 66A is known for its optical flux periodicity and complex jet kinematics. Using 22/43 GHz KaVa (KVN and VERA array) observations and 43 GHz VLBA (Very Long Baseline Array) archival data, we have found that its pc-scale jet has a twisted structure and that the inner jet undergoes periodic swings every 13 years. In this talk, we will describe the peculiar characteristics of 3C 66A...
The Yebes Observatory, operated by the National Geographic Institute of Spain (IGN), hosts a state-of-the-art 40-meter radio telescope equipped with a broad range of frequency receivers from S-band to W-band (2–90 GHz), all designed and mostly built in-house. All of them can be used in single-dish and VLBI observations. The ultra-wide K-, Q-, and W-band frontends are mounted on a single...
We present results from long-baseline VLBI test observations evaluating the performance of Frequency Phase Transfer (FPT) and Source/Frequency Phase Referencing (SFPR) at 22, 43, and 86 GHz using the Korean VLBI Network (KVN) and the Yebes-40m telescope in Spain (~9,000 km baseline). The ultimate goal is to monitor the orbital motion of supermassive black hole binaries (SMBHBs) using...
The new K/Q/W tri-band receivers cover a number of important maser transitions
of methanol, water, SiO and other molecules. Many of these transitions are
excited in the vicinity of massive young stellar objects (MYSOs). Different
molecules and transitions have different excitation mechanisms and may originate
in different parts of the MYSO's environment, such as the circumstellar...
In this presentation, the status of the tri-band receivers acquired, within the PON-SRT program, for the SRT, Medicina and Noto radio telescopes will be shown. Then, I will proceed with a description on the laboratory tests, integration into radio telescopes and first light.
