Science highlight: Tracing galaxy mass loss via OH absorption at high redshift

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Mass loss from high-redshift galaxies is crucial in quenching star formation and enriching the intergalactic medium. Only limited information is available on the gas mass loss of galaxies at z>6. Using ALMA observations of OH 119 μm doublet toward a small sample of high-redshift unobscured QSO host galaxies, Butler et al. (2023, ApJ 944, 134) trace the outflows blueshifted absorption. Estimating the mass loss rate, the authors conclude that the mass loss is likely driven by star formation alone, with only a small contribution from the AGN. Viewing geometry and coverage factor are important factors in the interpretation of the absorption lines and inference of the mass loss rates. Higher resolution follow-up observations with ALMA, and data on a larger sample, will further strengthen the presented results. This work included contributions from astronomers from Leiden, Delft, Heidelberg and Bologna.

Above Figure: ALMA continuum (left) and OH absorption (right) observations of one of the unobscured QSO host galaxies studied by Butler et al. (2023). Blueshifted OH 119 μm absorption traces star-formation driven mass-loss from this z=6 galaxy.

Meeting of ALMA Young Astronomers 2023

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March 10th marked the successful completion of the second Meeting of ALMA Young Astronomers, MAYA 2023. The goal of MAYA is to provide a platform where early career astronomers can present their recent ALMA work, and to facilitate new collaborations and projects through the interaction with other participants and staff working in the ARC nodes.

Work presented at MAYA showcased some of the most exciting research done by early-career astronomers who are interested in ALMA. This week-long virtual conference included participants from around the world who gave talks on topics ranging from protoplanetary disks to high redshift galaxies. The conference had a total of 192 registrants, with 69 abstracts submitted. There were 51 talks on the final MAYA 2023 program, and the majority of these talks have been recorded and will be available shortly on the YouTube channel of the European ALMA Regional Centre Network. The full program can be found on the MAYA 2023 webpage, along with an abstract booklet, and PDFs of the three invited talks (Astronomer on Duty, the ALMA Science Archive, and the Future of ALMA).

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ALMA Data Reduction Training Day: Dec 9, 2022

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Following the 6th Netherlands ALMA Science Day, on Thursday, December 8, 2022, we will host an ALMA Data Reduction Training Day in-person in HL 111.

The training will begin at 9:30 AM and continue into the afternoon with coffee breaks and an hour lunch break. The Allegro team will be presenting a series of talks that cover the following topics: how to go from the archive to obtaining calibrated visibilities, calibration, imaging, self-calibration, and analysis tools. There will be a short Question & Answer session at the end of each talk (approximately five minutes).

Several of the talks will include a hands-on component that participants can follow along with. Information on how to connect to the Allegro workstations will be provided prior to the training day.

Program* December 9, 2022
9:15-9:30 Welcome
9:30-10:15 Aida Ahmadi ALMA data: From the archive to calibrated visibilities
10:15-11:00 Andrés Pérez-Sánchez Calibration
11:00-11:20 Coffee break
11:20-12:20 Ashley Bemis Imaging & tclean
12:20-12:50 Andrés Pérez-Sánchez Self-calibration
12:50-14:30 Lunch break
14:30-15:30 Alex Hygate Analysis Tools
15:30-16:30 Aida Ahmadi Intro to CARTA

* Note that this is a rough schedule as we plan to dedicate plenty of time for questions after each session.

Directions to Leiden Observatory

Note that this is not the old observatory in the center of Leiden. Instructions on how to get to Leiden Observatory, including transportation from Schiphol Airport or the central trains station, can be found here. Note that these instructions specify the route to the Lorentz Center, which is in the building on the right in the photo below (Oort building). The event will be held in the joining taller building –  Huygens building. Leiden Observatory is located on the 4-5th floors of both buildings, and the Allegro offices are located on the 11th floor of the Huygens building.

Locations inside the building

Workspaces reserved for the ALMA Data Reduction Training Day on December 9, 2022 are located in room HL-111 on the 1st floor of the Huygens building. There is a reception at the entrance of the building where they can provide you with directions.

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6th Netherlands ALMA Science Day: Dec. 8, 2022

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Allegro announces the 6th Netherlands ALMA Science Day, that will take place in person at Leiden Observatory on Thursday, December 8, 2022. At the Science Day, we will highlight the latest scientific results obtained with ALMA by the Netherlands astronomical community. The meeting will also allow ample time to discuss user experiences and other ALMA related topics. Registration for contributed talks is now open (deadline: Nov. 25, 2022) and we welcome contributions in all science areas. 

Following the Science Day, on Friday, December 9, 2022, we will also host an introductory ALMA Data Reduction Training Day. At this workshop, Allegro fellows will introduce CASA and ALMA data reduction techniques, share tips & tricks, and offer hands-on training in exploring the ALMA archive, self-calibration, imaging, and data analysis.

 

6th Netherlands ALMA Science Day
Dec. 8, 2022
Session I (Chair: Ashley Bemis)
1000-1005 Welcome (Allegro)
1005-1020 Joshua Butterworth (Leiden) Understanding if molecular ratios can be used as diagnostics of AGN and starburst activity: The case of NGC 1068
1020-1035 Ko-Yun (Monica) Huang (Leiden) Reconstruct shock history in NGC 253 with ALCHEMI
1035-1050 Mathilde Bouvier (Leiden) Sulphur-bearing species in NGC 253: what do they trace?
1050-1105 Ian Roberts (Leiden) Gas Compression from Ram Pressure in Nearby Cluster Galaxies
1105-1120 Raffaella Morganti (ASTRON, Groningen) On-going feeding of the radio galaxy 3C84
1120-1145 Gergö Popping (ESO) The latest from ALMA
1145-1205 ALMA Q&A and discussion
1205-1300 Lunch
Session II (Chair: Alex Hygate)
1300-1330 Rychard Bouwens (Leiden) The REBELS Large Program
1330-1345 Ivana van Leeuwen (Leiden) Dust-obscured star formation at z ∼ 6 from [CII] selected companion galaxies
1345-1400 Violeta Gamez Rosas (Leiden) Kinematics of the molecular torus in NGC 1068
1400-1415 Di Wen (Groningen) Testing Primordial Black Hole Dark Matter with ALMA Observations of Strong Gravitational Lensing
1415-1430 Hector Olivares (Nijmegen) Black hole physics and the Event Horizon Telescope
1430-1445 Short break
Session III (Chair: Aida Ahmadi)
1445-1500 Margot Leemker (Leiden) Hot or cold: finding the temperatures in transition disks using ALMA
1500-1515 Logan Francis (Leiden) Accretion Burst Echoes as Probes of Protostellar Environments and Episodic Mass Assembly
1515-1530 Milou Temmink (Leiden) Investigating the Cold Chemistry in the Asymmetric Disk of HD 142527
1530-1545 Lucas Stapper (Leiden) Herbig disks: flat vs flared, really?
1600 End of meeting
Directions to Leiden Observatory

The address of Leiden Observatory is Niels Bohrweg 2, 2333 CA Leiden. Note that this is not the old observatory in the center of Leiden. Instructions on how to get to Leiden Observatory, including transportation from Schiphol Airport or the central trains station, can be found here. Leiden Observatory is located on the 4-5th floors of the Oort building (seen on the right in the photo below), and the Huygens building (the taller building seen on the left in the photo below). Allegro offices are located on the 11th floor of the Huygens building.

The Science Day will take place in room HL 414 on the 4th floor of the Huygens building. We will have signs and there is also a reception at the entrance of the building where they can provide you with directions.

For those joining us online, connection details will be sent to you by email before the start of the event.

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Instructions from CASSIS cookbook

Allegro releases CASSIS cookbook

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Allegro has developed a simple cookbook that describes how to use CASSIS, a free interactive spectrum analyser. It is a powerful and user-friendly software to efficiently analyse spectral lines, for example to determine physical conditions like column densities and excitation temperatures of different molecules.

The cookbook material can be downloaded from the Allegro website. It describes how to use CASSIS with a special emphasis on ALMA observations, including instructions on how to extract a spectrum from ALMA data in a format that can be read by CASSIS. The document comes with hands-on practice material that can be downloaded as well. The material contains a copy of the cookbook, scripts, an ALMA dataset that can be used to extract a spectrum from, a spectrum formatted for CASSIS, and a folder with codes and files relevant for scripting CASSIS. Detailed instructions on how to install and use CASSIS can be found on the CASSIS website.

Don’t hesitate to e-mail us if you would like to use CASSIS on the Allegro computing nodes or if you encounter any issues using the cookbook.

Enjoy CASSIS in the ALMA era!

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Allegro launches Friends of Allegro 2023 program

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Allegro is looking for applicants for its Friends of Allegro 2023 program, which aims to expand and facilitate connections across the ALMA community in the Netherlands. This program is open to Ph.D. students and Postdoctoral Researchers at Dutch research institutes and universities. Members of the Friends of Allegro program will be given opportunities to develop ALMA-related skills and expertise further. They will also help Allegro spread relevant ALMA-related communications within their institutes.

If you are interested in participating in this program, please fill out this form. We will contact successful applicants near the end of December for participation in 2023. If you are interested in learning more, don’t hesitate to contact us at alma@strw.leidenuniv.nl.

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Self-calibration and improving image fidelity for ALMA and other interferometers

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The high quality of ALMA calibrated data sets allows researchers to tune the imaging parameters to their preferences, and to produce images ready for publication in few steps.
Sometimes the exploratory analysis of calibrated datasets can also show the need for post-calibration processing. Identifying and/or diagnosing imaging problems from structured artifacts, or to identify errors induced from the observations and/or prior calibration, could save valuable time when researchers deal with challenging datasets.

Although there is extensive documentation out there for experts, a document accessible for researchers less experienced with radio interferometry was still missing. Recently, Anita Richards et al. published an internal ALMA memo (620), also available in the ArXiv, with the title “Self-calibration and improving image fidelity for ALMA and other interferometers”.

This document is an up-to-date manual with practical explanations of the errors normally found in interferometric data, and corrections that can be applied.
The main topic is self-calibration, in particular with ALMA data. However, the concepts explained are also relevant for other long-baseline interferometers.
The document includes examples and a quick-start guide for continuum self-calibration, as well as special cases.

Complementary to the ALMA Memo is the I-Train tutorial on self-calibration. In this tutorial, Anita Richards, Emily Moravec, Carmen Toribio, and Andrés Pérez explain and show examples of self-calibration.

Images from Bouwens et al. and Brunken et al.

ALMA probes atoms and molecules, near and far

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ALMA’s supreme capabilities to detect spectral lines across the Universe are beautifully illustrated in two recently published papers by astronomers in the Netherlands. Bouwens et al. (2022, ApJ 931, 160) give an overview of the design and results of the ALMA Large Program REBELS. Using an efficient selection scheme, REBELS detects no less than 18 star-forming galaxies with bright [CII] 158 µm ISM cooling lines, out of a sample of 40 z>6.5 systems. This makes ALMA [CII] searches as efficient as Lyα to find high-redshift star-forming galaxies. Brunken et al. (2022, A&A 659, A29) stay closer to home and detect Complex Organic Molecules (COMs) in the highly asymmetric planet-forming disk around the young star IRS48. The disk around this star has a very pronounced ‘dust and ice trap’ where material accumulates, and future planet(esimals) may form. Brunken et al. report the first detection of dimethyl ether (CH3OCH3) vapor in a planet-forming disk, and a tentative detection of methyl formate (CH3OCHO) vapor. The presence of these molecules shows that a wide variety of oxygen-carrying COMs are present in the birth environment of planets. As these two papers show, wherever ALMA turns its ‘eye’, atoms and molecules leap out at us.

ALMA Proposal Preparation Day 2022

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The Allegro ARC Node would like to invite you to attend a proposal preparation workshop on March 28, 2022. The aim of this workshop is to assist you in making the most out of ALMA’s new capabilities, getting an overview of the new modes offered, and proposal preparation through the ALMA Observing Tool (OT). We will also offer guidance with writing double-anonymous proposals and in the new stages of proposal writing and reviewing (the “distributed proposal review process”) that has been in use from Cycle 8 2021. An overview of important dates and what’s offered in Cycle 9 will be released with the Call for Proposals on March 24, 2022.

The workshop will consist of:

  1. an in-person event with the Allegro team on March 28th with a few presentations and an extensive Q&A session. The workshop will take place at Leiden Observatory, but we will organise streaming for those unable to travel.
  2. individual 1-1 support that can be booked at any time (e-mail us)

You can register to attend the workshop using this registration form. Deadline for registration: March 20, 2022

Program March 28, 2022
before 11:00 Arrival to Allegro offices (HL 1122)
11:00-11:30 Welcome coffee/tea & cookies (HL 11th floor)
11:30-12:00 ALMA science overview Katharina Immer & Aida Ahmadi
12:00-12:20 ALMA Call for proposals & capabilities in Cycle 9 Violette Impellizzeri
12:20-13:15 Lunch
13:15-13:35 Distributed peer review Katharina Immer
13:35-13:50 Dual anonymous proposal review Andrés Pérez-Sánchez
13:50-14:15 How to write an ALMA proposal Violette Impellizzeri
14:15-14:35 Break
14:35-15:10 The ALMA Observing Tool Ashley Bemis
15:10-15:30 Simulating ALMA observations Alex Hygate
15:30-15:50 Mining the ALMA archive Aida Ahmadi
15:50-16:10 Break
16:10-16:30 Open Q&A session
 
Registered participants

Michiel Hogerheijde Leiden Observatory
Violette Impellizzeri Leiden Observatory
Alex Hygate Leiden Observatory
Andrés Pérez-Sánchez Leiden Observatory
Ashley Bemis Leiden Observatory
Aida Ahmadi Leiden Observatory
Katharina Immer Leiden Observatory
Marco Grossi Observatório do Valongo, UFRJ
Sander Schouws Leiden Observatory
Maren Hempel Universidad Andres Bello , Chile
Veronica Allen University of Groningen
Wuji Wang Center for Astronomy of Heidelberg University
Pooneh Nazari Leiden Observatory
Simin Tong Leiden Observatory
Thomas Steinmetz Nicolaus Copernicus Center for Astronomy (Torun)
Di Wen Kapteyn Astronomical Institute
Agnieszka Kobak Nicolaus Copernicus Center for Astronomy (Torun)
Alice Booth Leiden Observatory
Lucas Stapper Leiden Observatory
Margot Leemker Leiden Observatory
Bayron Portilla Revelo Kapteyn Astronomical Institute
Marta Frias Castillo Leiden Observatory
Fernanda Roman de Oliveira University of Groningen
Ko-Yun (Monica) Huang Leiden Observatory

 
Directions to Leiden Observatory

The address of Leiden Observatory is Niels Bohrweg 2, 2333 CA Leiden. Note that this is not the old observatory in the center of Leiden. Instructions on how to get to Leiden Observatory, including transportation from Schiphol Airport or the central trains station, can be found here. Leiden Observatory is located on the 4-5th floors of the Oort building (seen on the right in the photo below), and the Huygens building (the taller building seen on the left in the photo below). Allegro offices are located on the 11th floor of the Huygens building.

Upon arrival and before the start of the event, join us on the 11th floor of the Huygens building for tea, coffee, and cookies. The workshop will take place in room HL 106-109 on the 1st floor of the Huygens building. We will have signs and there is also a reception at the entrance of the building where they can provide you with directions.

For those joining us online, connection details will be sent to you by email before the start of the event.

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