European ARC Newsletter
01 Oct 2020

Welcome to the European ALMA Regional Centre Newsletter!  

This Newsletter is a compilation of recent European ALMA Regional Centre Announcement items. The newsletter appears on a bimonthly basis. In addition to these Announcements the Newsletter provides an inside look into ALMA operations, showcases some of the exciting science carried out with ALMA by our European colleagues, as well as informs you about ALMA or ALMA-related meetings.

Up-to-date information about weather, configuration and scheduling can be found on the ALMA Status page.

European ARC Announcements

ALMA starts the process of recovering the telescope array

01 Oct 2020:

Dear colleagues,

The past several months have been an extraordinary period as a result of the global coronavirus pandemic. Everyone at ALMA hopes that you and your families are safe and healthy, and we extend our thoughts to those who have been directly affected by the pandemic.

For six months, almost the whole ALMA site has been shut down – power, water treatment, and running water - with only a single piece of key equipment (the hydrogen maser) still powered and checked daily as one of the tasks of the ALMA Caretaker Teams  - the teams who have ensured the safety and security of the ALMA Observatory through the shutdown.   

With the improving pandemic situation in Chile, ALMA is now scheduled to begin the long process of recovering the telescope array in the Atacama on October 1st, 2020, starting with preparation of the ALMA Operations Support Facility (OSF) at 2900 metres for the return of staff and contractors.

The road to recovery of operations, and ultimately science observations – a milestone that will not take place this year - has been carefully planned. It is difficult to predict the exact timeline since several aspects of the plan depend on prevailing conditions not under our control. However, the following describes the current plan of activities and schedule for the return of ALMA to science operations.

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ALMA Regional Centre Community Assembly

01 Oct 2020:

The European ALMA Regional Centre invites all European ALMA users to a short virtual community assembly on October 8 at 10:00 CEST. After a long period of suspended science observing, there is now a path towards getting back on sky and collecting science data with ALMA again. At this community meeting, we will update you on the time line for recovery and can answer any questions you may have on your ALMA projects and support from the European ARC network.

Reserve the date: 8 October at 10:00 CEST. The meeting can be accessed at this link. Looking forward to seeing you then!

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ALMA is redesigning its user experience - be part of it!

21 Sep 2020:

It has been a while since ALMA antennas have pointed towards the sky. Many of you have used this time to mine the ALMA archive, do great science, think of future projects and contemplate about your past experience with ALMA data and the services, tools and user support offered since Cycle 0.

While the antennas are taking an unanticipated break, ALMA is launching a new global project to Redesign the User eXperience (RedUX). As part of RedUX we will establish focus groups to discuss specific aspects of the ALMA user experience. By volunteering to join a focus group, you can help shape the future of ALMA. If you are interested in contributing to RedUX (and in receiving a small gift at the end of the exercise, as a token of our appreciation for your contribution), please fill in this form. The form is not anonymous, as we need your contact details in order to be able to get in touch with you.

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Data delivery of the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS)

20 Sep 2020:

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) is a 3D survey of gas and dust in distant galaxies. It focuses on the best-studied cosmological deep field, the iconic Hubble Ultra Deep Field. Capitalizing on the unparalleled sensitivity of ALMA the ASPECS data unveil reservoirs of molecular gas and dust in galaxies up to redshifts z~4, when the Universe was only 1/8th of today's age. This interstellar medium constitutes the matter out of which stars form, and it is thus a prerequisite of the star formation process, and thus a key driver for galaxy evolution. The ASPECS data - that can be obtained from this page - provide the most sensitive image of the sky at 1.2 mm available to date, disclosing the emission of dust, which is heated up by the star formation.

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Comparing B2B and In-Band phase referencing and Calibrator separation angles.

20 Sep 2020:

Based on Extension of Capabilities (EOC) observations made in late 2017, the high-frequency long-baseline (HF-LB) team have recently published work detailing their extensive tests (please see the full article here). The main aim of the work was to compare standard phase referencing, defined as In-Band, with the band-to-band (B2B) technique. The latter technique allows the observatory to calibrate data using a phase calibrator observed at a lower frequency than the target source. The practical reason for B2B is that at higher and higher observing frequencies, quasars, used as phase calibrators become weaker and therefore a sufficiently bright one will often be at a large separation from the science target. This can result in less optimal calibration and imaging, something the team also aimed to clarify. To achieve their aims, the HF-LB team made observations in the In-Band and B2B modes where the modes shared the same close calibrators (within 2 deg of the targets), but also in cases where the In-Band calibrators were chosen to be further away, up to a maximal value of ~11 deg.

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ALMA science highlights


1. Complex stellar winds from evolved stars

Gallery of AGB stellar winds of 12 oxygen-rich AGB stars in 12CO J=2-1 emission. For each star, one spectral channel that is redshifted with respect to the local standard of rest velocity is shown in red, blueshifted in blue, and rest velocity in white. The scale bars have an angular extent of 1".

Binary interaction may explain the evolution of a spherical wind from an asymptotic giant branch (AGB) star into aspherical planetary nebula (PN). In a recent Science paper, Decin et al. (2020) present ALMA observations of a sample of AGB stars as part of the ATOMIUM Large Program, showing a range of non-spherical morphologies that are similar to those commonly observed in PNe. With the excellent sensitivity of ALMA, it is possible to classify the dominant wind morphology of an AGB star. A correlation is identified between the mass-loss rate and the prevailing geometry. Complex equatorial density enhancements are often found in AGB stars with low mass-loss rates while bipolar or spiral-like structures are found towards stars with higher mass-loss rates, suggesting that the shaping mechanism of AGB stellar winds depends on the mass-loss rate. The ATOMIUM Large Program would not have succeeded without the additional help by ESO Garching staff in making sure that the pipeline products met the requirements.


2. Revealing the intermediate-mass black hole at the heart of NGC 404

Left: Colour composite Hubble Space Telescope image of the centre of NGC 404. Right: ALMA CO (2-1) integrated intensity map of this same region, revealing the distribution of the molecular gas in the centre of this object with 0.7 pc resolution.

The co-evolution of supermassive black holes and galaxies is a crucial component of our modern galaxy formation paradigm. Understanding the underlying correlations between galaxies and black holes is still difficult, however, especially in low mass galaxies. In a recent MNRAS paper, Davis et al. (2020) present new ALMA observations of NGC 404, a nearby dwarf elliptical galaxy. They achieve an angular resolution of less than a parsec, resolving the molecular clouds which form flocculent ring/arm structures in the centre of this system. They use both the rotation of the central molecular disc/torus material, and the stellar kinematics to independently measure a mass of 5.5 x 105 Msun for NGC 404's intermediate-mass black hole. This lays to rest a decade of conflicting measurements of the central BH mass. They show these contradictory results arose due to the presence of the previously neglected molecular material in the core of this galaxy, which only ALMA is sensitive enough to reveal.


Upcoming ALMA or ALMA-related Meetings

Our understanding of planet formation has been significantly challenged by recent observations during the last years. Recent high-resolution observations by ALMA and SPHERE/VLT have found compelling evidence of planet signatures much earlier than what was typically assumed, questioning the time at which planet formation takes place. This ESO/NRAO workshop aims to discuss the emerging new paradigm of planet formation. The program will offer a broad view of the field, covering from the early stages of disks still embedded in their parental envelope to the times when full planetary systems are formed and only a few remnants of the progenitor disk are left. The conference will take place virtually from 7 to 11 December 2020 (more information can be found here).