Science Highlight: Most distant rotating disc galaxy found

A team led by Leiden Observatory researchers has discovered the most distant disc galaxy yet observed. The observations were conducted as part of the ALMA Large Program REBELS: Reionization Era Bright Emission Lines Survey, thus the disc galaxy has been dubbed REBELS-25. The galaxy seems as orderly as present-day galaxies, but we see it as it was when the Universe was only 700 million years old. This is surprising because, according to our current understanding of galaxy formation, such early galaxies are expected to appear more chaotic. “According to our understanding of galaxy formation, we expect most early galaxies to be small and messy looking,” says Jacqueline Hodge, an astronomer at Leiden University, and co-author of the study. However, both the structure and the rotation of REBELS-25 were revealed using ALMA data and the galaxy is strongly rotating and orderly.

Current theories suggest that billions of years of evolution must have elapsed for a galaxy to be as orderly as our own Milky Way — a rotating disc with tidy structures like spiral arms. The detection of REBELS-25, however, challenges that timescale.  “Seeing a galaxy with such similarities to our own Milky Way, that is strongly rotation-dominated, challenges our understanding of how quickly galaxies in the early Universe evolve into the orderly galaxies of today’s Cosmos,” says Lucie Rowland, a doctoral student at Leiden University and first author of the study.

REBELS-25 was initially detected in previous observations, also conducted with ALMA, by the same team. At the time, it was an exciting discovery, showing hints of rotation. Toproperly discern the structure and motion of the galaxy, the team performed follow-up observations with ALMA at a higher resolution, which confirmed its record-breaking nature. “ALMA is the only telescope in existence with the sensitivity and resolution to achieve this,” says Renske Smit, a researcher at Liverpool John Moores University in the UK and co-author of the study.

Surprisingly, the data also hinted at more developed features similar to those of the Milky Way, like a central elongated bar and even spiral arms. However, more observations will be needed to confirm this. “Finding further evidence of more evolved structures would be an exciting discovery, as it would be the most distant galaxy with such structures observed to date,” says Rowland.

Staff changes

Allegro’s newest members are postdocs Pascal Keller and Joshiwa van Marrewijk!

Pascal Keller joined Allegro in May 2024. He did his PhD titled “Investigating the Epoch of Reionisation with Radio Interferometers” at the Cavendish Astrophysics group of the University of Cambridge. His research focuses on developing and applying non-standard analysis techniques to radio interferometric data. He is particularly interested in using calibration-insensitive closure invariants such as the “closure phase” to search for the redshifted 21 cm signal of neutral hydrogen during the Epoch of Reionisation (EoR). As part of his thesis, he applied the “closure phase method” to data from the Hydrogen Epoch of Reionization array (HERA), producing robust upper limits on the spatial fluctuations of the EoR signal.

Joshiwa van Marrewijk will join Allegro in October 2024. He did his PhD at ESO in Garching, titled “The birth of cosmic structures as revealed by observations in the (sub-)mm bands”. His research focuses on how galaxies and galaxy clusters form, particularly at two key moments in cosmic history: the epoch of reionization and protoclusters. During his PhD, Joshiwa developed innovative methods to analyse ALMA data in the uv-plane and created a novel simulation tool named maria used for forecasting bolometric single-dish observations and studying phase fluctuations caused by the ever-changing atmosphere.  While his work often reveals the challenges of pushing observations to extreme redshifts, it’s also paving the way for the next generation of (sub-)mm astronomy and provides useful tools to analyse to get the best science out of the observations.

Meanwhile, we said good-bye Dr. Ko-Yun (Monica) Huang this summer. We would like to express our gratitude to Monica for her amazing service at Allegro! We will miss her greatly, and wish her all the best on her new path!

 

Lastly, we are excited that Dr. Violette Impellizzeri will join ASTRON as head of the Astronomy & Operations department. She started her new duties at ASTRON on 1 September 2024, but will still be working at the Allegro ARC Node partially until March 2025, to enable a smooth transition for the new group, new arrivals and daily activities. At ASTRON, Violette will be closely involved in the commissioning efforts for LOFAR2.0, the deployment of the SKA Dutch regional center and astronomy research activities at the institute.

Violette  has been part of ALMA since 2011, when she relocated to the Joint ALMA Observatory (JAO) in Chile as a commissioning postdoc and science fellow. Her involvement during the commissioning phase included early VLBI testing, science verification, and the implementation of high-frequency observing techniques, also known as band-to-band phase transfer. As operations commenced in 2014, she assumed the role of an operations astronomer with added responsibilities such as leading the Phase II Group (P2G), serving as a liaison for VLBI activities (VLBI friend of telescope), and heading the Proposal Handling Team (PHT). In October 2020, she joined the Allegro ARC Node in Leiden as the Program Manager, providing assistance to the ALMA community in the Netherlands.

Moving to ASTRON, Violette said she hopes she can help create further synergies and collaborations among our frequency domains in the coming years, as we are living through a transformation with the exciting WSU upgrade matching the ongoing constructions of SKA and the LOFAR 2.0 observatory.

Science Day: November 29, 2024

Allegro is pleased to announce our annual Science Day, which will take place at Leiden Observatory in our new Gorlaeus building on 29 November in BE.0.10. We would like to invite all members of our communities to present your latest scientific results obtained with ALMA at the event!

During the Science Day, we will also have talks related to ALMA technical aspects, news, and outlook—focusing on the changes that the Wide-band Sensitivity Upgrade (WSU) will bring. We will discuss the resources that ALMA observers currently need (and anticipate needing), with a particular emphasis on Allegro’s role in supporting the community in the Netherlands.

Details on invited speakers and the program will be sent to our mailing list soon!

Initial registration can be completed here!

Four of the Atacama Large Millimeter/submillimeter Array (ALMA) antennae — 12 metres in diameter — line up against the night sky in Chile’s Atacama Desert.

EAS Meeting

In July the European ARC network set up a booth at the annual European Astronomical Society (EAS) meeting, where conference participants could pick up a variety of ALMA related stickers, watch an informative video about ALMA and the ARC network, or enjoy a casual chat with one of the ARC representatives. This was a great opportunity for the ARC network to promote its services to the astronomy community and spread excitement about ALMA science and developments.

Updates from the Wideband Sensitivity Upgrade Workshop

In June ESO hosted a workshop focused on ALMA’s upcoming Wideband Sensitivity Upgrade (WSU). The workshop, titled “The promises and challenges of the ALMA Wideband Sensitivity Upgrade”, presented the upgrade and showcased the science that will be enabled in the upcoming years. It was also an opportunity to solicit input from the ALMA community that will be used to inform priorities during the commissioning phase.

In short, the WSU is well-underway and consists of an increase of the instantaneous spectral bandwidth by as much as a factor of four, while retaining full spectral resolution over the entire bandwidth. The result is an increase of the spectral scan speed up to a factor of 50 for the highest spectral resolution. In addition, an upgrade of the full signal chain of ALMA – from the receivers and digitizers, all the way through to the correlated data – will result in increases in sensitivity for all observations.

You can watch a video about the WSU here!

ALM Cycle 11 Proposal Submission Statistics

The ALMA Cycle 11 proposal submission statistics set some new records! Although the number of overall submitted proposals seems to be stabilising with 1712 proposals this semester, the number of hours requested on the 12-meter array continues to increase each cycle with over 30000 hours requested this cycle. The region with the highest number of proposals submitted was (again) Europe with a request of 11946 hours on the 12-m array, leading to the highest oversubscription of any region (over 8). East Asia and North America both had oversubscriptions of about 6.5, and Chile saw a big jump up in oversubscription which is now over 5. Band 6 remained the most popular this cycle, and Band 1 was requested by about 10% of proposals in its debut cycle.

The percentages of proposals for the 12-m array per region, science category, and requested receiver band for regular proposals are shown in the figure below.

42 large programs were submitted, of which four were awarded: two in the Circumstellar Disks, Exoplanets, and the Solar System category; and two in the Cosmology and High Redshift Universe category.

In Cycle 11, 60 proposals were submitted from the Netherlands. From these, 16 were accepted with an A, B or C rating. Worldwide, Netherlands-based astronomers were involved in 103 accepted proposals representing close to 2000 hours of ALMA time. This includes 16 researchers as PI and 106 individuals as co-I.

More details on the submission statistics can be found here.

European ALMA School

In June the European ALMA regional center organised the first European ALMA school, hosted by the UK regional node in Manchester. The school was a full week of lectures and hands-on activities related to interferometry, and ALMA specifically. Topics ranged from calibration techniques, to the specifics of the products that ALMA delivers, to an overview of the science that’s been done with ALMA over its 10-year lifespan. On top of the lectures, there was a visit to Jodrell Bank Observatory. With about 70 participants, the school was a big success, and we are looking forward to planning similar events in the future!

CASA Training Event

Allegro will host a training event on 23 October introducing the software packages that are commonly used to work with ALMA data: CASA and CARTA. We will briefly introduce ALMA and Allegro, and start looking at ALMA data using these software packages. The aim of the workshop is to get researchers started using ALMA data, and to point them to the resources they’ll need once they embark on their own projects. The workshop is geared towards first time users of ALMA data.

Please let your students, especially ones starting ALMA-related projects, know about the workshop.

You can express interest using this link.