A study by the Group for Advanced Receiver Development (GARD, Sweden) to develop new fabrication technology for sub-micron size Aluminium Nitride (AlN) barrier Superconductor Insulator Superconductor (SIS) junctions has been successfully completed. These SIS junctions are at the core of most ALMA receivers where the sky signal is mixed with the Local Oscillator to tune the receivers to the desired frequency.
A development study aimed to validate and improve the current atmospheric radiative transfer model implemented for ALMA (atmospheric transmission model, ATM) has been successfully completed. The model is important for both planning and helping in the calibration of ground-based observations at millimeter and submillimeter wavelengths.
First ever European ALMA School takes place in Manchester
Last month, the first ever European ALMA School took place at The University of Manchester, UK. Organised by the European ARC Network, this event offered extensive training on various aspects of ALMA. Participants learned about interferometry basics, data calibration and imaging, data visualisation and analysis, the ALMA Science Archive, proposal preparation and observations, and the future of ALMA.
Thank you to everyone who attended and contributed to making this event a success! All talks and links to tutorial materials are available on the meeting webpage:https://sites.google.com/view/eu-alma-school-2024/home
Introducing the Wideband Sensitivity Upgrade (WSU) to the user community
Over 150 researchers and engineers participated in the ESO workshop "The Promises and Challenges of the ALMA Wideband Sensitivity Upgrade" held in Garching from 24 to 28 June 2024. This workshop was the first event dedicated to introduce all details of this ambitious upgrade project to the user community. The event touched on a wide range of challenges that need to be addressed by the WSU to deliver an increased bandwidth of up to four times the current one at full spectra resolution and improved sensitivity. The technical presentations included the new Advanced Technology ALMA Correlator (ATAC) offering a much more flexible setup than the current one, the new digitizers which will allow to cover IF ranges from 2 to 20 GHz with increased digitization efficiency, new cryogenic Low Noise Amplifiers to allow increased bandwidth in several of the receivers, as well as dedicated presentations of all receivers to be upgraded. The increased data rates by over an order of magnitude pose a significant challenge to the data processing and archive, which were addressed by several presentations.
Mixed throughout these technical talks, the workshop also presented the promises of the WSU for the full ALMA user community ranging from the Sun, the solar system, planet-forming disks, star formation and evolution, astrochemistry, the interstellar medium, nearby galaxies, AGN, galaxy clusters, the distant Universe, as well as special modes such as time domain science, polarimetry and VLBI. These topics all benefit from the range of increased capabilities offered by the WSU, and it was enlightening to see how the technological advances promise to translate into new science. The workshop programme included eight discussion sessions, where the engineers and astronomers directly interacted with each other to understand the challenges and importance of the new capabilities. The meeting ended with a brief outlook to the future of ALMA in the 2040s.
ALMA science highlight
ALMA high-resolution observations unveil planet formation shaping molecular emission in the PDS 70 disk
Overview of ALMA observations of the PDS 70 disk. Central panel: ALMA band 7 continuum observations (Benisty et al., 2021), together with the marginal localized signature near PDS 70 b in a formaldehyde line (in blue). All around the central panel, the spatial distribution of the line emission of the various molecules covered by ALMA band 6 observations (program ID 2019.1.01619.S) is presented, and compared to the bright ring in the continuum emission (white contours), and the two planets' position (white dots).
While a rich demography of exoplanets has been recently collected, the formation pathway of planets in their protoplanetary disks is still largely unconstrained. Directly detecting faint protoplanets still embedded in their natal environment is challenging even at sensitivities and spatial resolutions provided by ALMA. The transition disk around PDS 70 is the only source with a multiwavelength direct detection of two protoplanets, including ALMA continuum observations, which revealed a circumplanetary disk around PDS 70c. This makes PDS 70 the best source where to study the interplay between forming planets and their natal environment and unveil the conditions under which the two planets are building their atmospheres.
Rampinelli et al. (2024) presented an overview of high-resolution and deep-sensitivity ALMA line emission observations of a rich molecular inventory in the PDS 70 disk. They show that most of the molecular tracers present a peak of the emission at the disk cavity wall, because of the efficient irradiation favoured by the large dust cavity carved by the two protoplanets. This reveals how planet formation can shape the line emission morphology. On the other hand, a protoplanet is also expected to result in local signatures of accretion in line emission observations: Rampinelli et al. (2024) detected possible evidence of planetary accretion heating near PDS 70b, in the asymmetric emission of a higher energetic formaldehyde line.
ALMA WSU highlight
The ALMA Wideband Sensitivity Upgrade is not taking a summer break. Instead, all activities around the WSU are going full steam ahead. The years 2024 and 2025 are characterized by a series of important reviews, ranging from preliminary design reviews (PDRs) of the individual subsystems that together constitute the WSU, to system-wide reviews addressing the scheduling, technical and financial aspects of the WSU. PDRs are an important step in the lifecycle of development projects and examine whether requirements and external interfaces are identified, that the proposed baseline design meets these requirements, and that risks are identified and mitigated.
Two such PDR reviews were held in June, for the new correlator (ATAC) and OSF Correlator Room (OCRO). Both projects metthe review criteria with no significant issues identified and with a recommendation that they both proceed to the criticaldesign phase. The ATAC correlator will initially be able to ingest 4x the current ALMA system bandwidth (32 GHz per polarization) and process up to 2x the current bandwidth (16 GHz per polarization). The processing hardware can be readily expanded to the full 4x bandwidth in a future upgrade. ATAC will be located at the OSF Technical Building at 2,900m for reasons of power efficiency, ease of operations and maintenance, and to allow it to be commissioned without interference with the operation of the baseline correlator, located at the Array Operations Site at 5,000m elevation.
Early July, the WSU underwent an important external review in Santiago, known as the delta-System Requirement Review and Initial Program Plan Review. This completed a two-year effort to perform a major update of the system technical requirements. The panel also assessed the technical and operational feasibility, and the completeness of the major WSU systems and subsystem design concepts.
Later this year, one of the European critical contributions to the WSU – the Digitizer/DSPOT project - will undergo the PDR phase. Around that time, we will provide more details on this project.
Imagine a crack team of just 12 performers stationed at the European Southern Observatory (ESO). They aren't your average garage band; they are the ALMA Regional Centre (ARC), attending to the cosmic songs played by ALMA.
Their Mission: Conduct a Radio Astronomy Remix
Masterminds of the Observing Tool: ARC wizards, the Subsystem Scientists, wield the Observing Tool (OT) to ensure ALMA observations are conducted with pinpoint precision. They're basically the mixers of the data flow console.
Phase 2 Scheduling Block Curators: Think of them as cosmic traffic controllers. The Phase 2 Group meticulously concoct observation blocks for all approved ALMA projects, making sure European-led programs get their time in the celestial spotlight.
Calibrated Measurement Set Deliverers: Need high-fidelity recordings of the cosmos? The ARC delivers Calibrated Measurement Sets upon request, like a celestial record store fulfilling orders for all ALMA observations since Cycle 1.
European User Orchestra Conductors: The ESO ARC acts as a Maestro, conducting a network of ARC nodes across Europe. Together, they tune in the European astronomy community to the faint cosmic whispers with ALMA.
(Meta)Data DJs: The ARC stars help unleash the power of ALMA's cosmic Archive for groundbreaking research.
Their Special Skills: Unlocking the Secrets of the Universe
High-Frequency, Long-Baseline Observation Masters: These ARC sharpshooters know exactly how to capture ethereal murmurs of the cosmos.
Interferometric Data Impresarios: They can decipher the complex rhythms of interferometric data, untangling the secrets hidden within.
Advanced Imaging Algorithm Composers: Think of them as the engineers who design the tools to create stunning cosmic portraits from raw data.
Helpdesk Heroes: The ALMA Helpdesk is the first line of defense for any European astronomer facing data reduction woes (using CASA, the cosmic radio data processor), hitting an archive sour note or encountering other misfortunes. They're basically the data herders and user support cheerleaders, all rolled into one.
So, the next time you tune into the Universe through radio astronomy, remember the ARC at ESO. They are there for you, to help you decode the cosmic whispers and to ensure you have the tools and support to unravel the mysteries of the Universe. Tune in with the ARC and unravel the cosmic mysteries yourself!
