We are thrilled to announce that the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) has been accredited as a María de Maeztu Unit of Excellence in the 2024 Call by the Spanish Ministry of Science and Innovation. This prestigious recognition marks the third time ICCUB has been honored with the María de Maeztu accreditation, following its initial award in 2014. 

This distinction highlights organizations with highly competitive research programs that are among the best in the world in their respective scientific areas. The evaluation and selection process are conducted independently by an international scientific committee of widely recognized researchers, who select both Severo Ochoa centers and María de Maeztu units under the same rigorous criteria. ICCUB is one of the 17 organizations (9 Severo Ochoa centers and 8 María de Maeztu units) selected in this annual competitive call. 

"It is the third time the ICCUB has obtained the Maria de Maeztu award, not an easy feat," says Xavier Luri, director of the ICCUB. "It is not only an acknowledgement of the outstanding science produced by our researchers, but also of the long-term vision and the continuous search of excellence at the ICCUB. This award will allow us to expand our contributions to many key scientific challenges." 

The accreditation provides funding to research organizations that demonstrate international scientific impact and leadership, actively embrace knowledge transfer, and collaborate with the business sector. Efforts in open access policies to scientific publications, outreach, and knowledge diffusion are also recognized.  

The María de Maeztu recognition is valid for four years and provides more than 500.000€ annually. This funding will allow the ICCUB to realize its strategic Research Plan, attract scientific talent and foster our outreach and communication initiatives. 

"This award provides ICCUB the means to realize its ambitious scientific vision over the next 4 years," says Licia Verde, scientific director of the ICCUB. "To me this represents a strong vote of confidence in the quality and impact of past work and the potential of the institute to push the frontiers of the science of the cosmos. I am excited for what the next 4 years will bring. ICCUB team, our best work is yet to come!" 

As a Unit of Excellence, ICCUB will remain in the SOMM Excellence Alliance, which promotes Spanish Excellence in research and enhances its social impact at national and international levels. 

The Institute of Cosmos Sciences Strategic Plan 

The funding will be used to address several scientific challenges:  

• Exploring physics beyond the current standard models of particles and cosmology: This involves a coordinated approach that integrates theoretical modeling, precision measurements, and sophisticated data analysis techniques to uncover new physics. 

• Studying the physics involved in producing gravitational wave sources: By researching the origins and processes of gravitational wave events, ICCUB seeks to provide novel insights into the strong gravity regime and the nature of compact binary coalescences. This research will be supported by ICCUB's active participation in major collaborations and surveys, enhancing our understanding of the universe's constituents. 

• Exploiting quantum resources for science and technology: This includes advancing quantum communication, computation, and hardware development. The goal is to harness quantum entanglement and superposition to drive innovations in communication security and computational capacity, positioning ICCUB at the forefront of the second quantum revolution. 
   

In addition to these scientific endeavors, the funding will support various institutional activities, including:  

• Boosting recruitment strategies and talent acquisition with a focus on gender balance. 

• Providing comprehensive training programs for doctoral and postdoctoral researchers. 

• Expanding the Mental Health and resilience program. 

• Attracting diverse funding sources, fostering international leadership, and enhancing knowledge and technology transfer. 

• Prioritizing diversity, equity, and inclusion programs to ensure a supportive and inclusive environment. 

• Expanding outreach and communication efforts to new formats and activities to reach wider audiences, while increasing inclusivity by adapting materials and workshops. 

This recognition is a testament to the collective effort and unwavering commitment to excellence of all our researchers, as well as an inspiration for future scientific achievements. 

Awarded Severo Ochoa Centers and Maria de Maeztu units 

The centers and units that have received the María de Maeztu accreditation are: the Universitat Pompeu Fabra's Department of Medicine and Life Sciences, the Universidad de Barcelona's Institut de Ciències del Cosmos, the Universidade de Santiago de Compostela's CIMUS - Centro de Investigación en Medicina Molecular y Enfermedades Crónicas, the Universidad de Valencia's Instituto de Ciencia Molecular, the Fundación IMDEA Software's IMDEA Software Institute, the Fundación Privada Institut Català de Paleoecologia Humana i Evolució Social's Institut Català de Paleoecologia Humana i Evolució Social, the Universidad Autónoma de Barcelona's Institut de Ciencia i Tecnologia Ambientals (ICTA), and the Universidad de Sevilla's Instituto Universitario de Investigación de Matemáticas de la Universidad de Sevilla (IMUS). 

The Severo Ochoa accreditations have been awarded to: the Institut de Física d'Altes Energies, the Centro Nacional de Investigaciones Oncológicas Carlos III, the Instituto de Ciencia de Materiales de Madrid (ICMM), the Fundació Institut Català d'Investigació Química (ICIQ), the Barcelona Graduate School of Economics, the Instituto de Ciencias Fotónicas, the Fundación Donostia International Physics Center, the Instituto de Ciencias del Mar (ICM), and the Estación Biológica de Doñana (EBD). 

Acknowledgements
 

Grant CEX2024-001451-M funded by MICIU/AEI/10.13039/501100011033.

The 2025 Jocelyn Bell Burnell Inspiration Medal recognizes arXiv's significant contributions to astrophysical research through its open, free, and global distribution of scientific articles. Since its inception in 1991, arXiv has revolutionized the dissemination of scientific knowledge, breaking down barriers imposed by costly journals and championing open access by providing unrestricted access to all users.

Licia Verde, ICREA researcher and ICCUB's Scientific Director, will represent arXiv at the upcoming European Astronomical Society (EAS) award ceremony, where the organization will receive the prestigious Jocelyn Bell Burnell Inspiration Medal for its revolutionizing impact on astrophysical research. Verde, who has been an advisor to arXiv since 2016, will accept the award together with Ralph Wijer (University of Amsterdam) on behalf of the organization.

Licia Verde expressed her admiration for arXiv, stating, “Arxiv is an incredibly successful and inspiring story. To me it is an ideal (open science) that became a reality, and a community of researchers. Arxiv relies on a small, highly effective and extremely dedicated team and a much larger body of volunteers. I am honoured to have had the opportunity to contribute to this community in an advisory role, to the arXiv mission and to the global process of democratisation of knowledge."

This recognition highlights the international presence and impact of ICCUB researchers, showcasing their contributions to global scientific advancements. It also underscores ICCUB's commitment to open science, a principle that promotes transparency, accessibility, and the democratization of knowledge. By actively participating in initiatives like arXiv, ICCUB demonstrates its dedication to making scientific research more inclusive and equitable, ensuring that valuable knowledge is accessible to researchers worldwide, regardless of financial barriers.

As the leading open-access preprint repository for physics, astronomy, and related disciplines, arXiv plays a fundamental role in ensuring that scientific knowledge is rapidly disseminated, openly accessible, and freely available to all. This democratization of knowledge allows researchers from different institutions and countries to engage with the latest findings without financial barriers.

By fundamentally changing how astronomical knowledge is shared, arXiv exemplifies the spirit of the Jocelyn Bell Burnell Inspiration Medal, celebrating contributions that extend beyond traditional research to inspire and enable progress in astronomy and empower the global scientific community.
 

The European Space Agency (ESA) has powered down its Gaia spacecraft after more than a decade spent gathering data that are now being used to unravel the secrets of our home galaxy.

On 27 March 2025, Gaia’s control team at ESA’s European Space Operations Centre carefully switched off the spacecraft’s subsystems and sent it into a ‘retirement orbit’ around the Sun.

Though the spacecraft’s operations are now over, the scientific exploitation of Gaia’s data has just begun.

Gaia’s stellar contributions

aunched in 2013, Gaia has transformed our understanding of the cosmos by precisely mapping the positions, distances, motions, and properties of nearly two billion stars and other celestial objects. It has provided the largest, most precise multi-dimensional map of our galaxy ever created, revealing its structure and evolution in unprecedented detail.

The mission uncovered evidence of past galactic mergers, identified new star clusters, contributed to the discovery of exoplanets and black holes, mapped millions of quasars and galaxies, and tracked hundreds of thousands of asteroids and comets. The mission has also enabled the creation of the best visualisation of how our galaxy might look to an outside observer.

“Gaia’s extensive data releases are a unique treasure trove for astrophysical research, and influence almost all disciplines in astronomy,” says Gaia Project Scientist Johannes Sahlmann. “Data release 4, planned for 2026, and the final Gaia legacy catalogues, planned for release no earlier than the end of 2030, will continue shaping our scientific understanding of the cosmos for decades to come.”

Spanish institutions have had a major contribution to the mission. "The Gaia team at the University of Barcelona has been working on the mission since its inception around 1997." says Xavier Luri, director of the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and member of the Gaia UB team. "We have participated in all its phases, from defining the scientific case and industrial design to data processing and scientific exploitation. Now, although we say farewell to Gaia, several years of work remain to fully process all the data collected over these years and publish two additional data releases (DR4 and DR5)."

Saying goodbye is never easy

Gaia far exceeded its planned lifetime of five years, and its fuel reserves are dwindling. The Gaia team carefully considered how best to dispose of the spacecraft in line with ESA’s efforts to responsibly dispose of its missions.

They wanted to find a way to prevent Gaia from drifting back towards its former home near the scientifically valuable second Lagrange point (L2) of the Sun-Earth system and minimise any potential interference with other missions in the region.

“Switching off a spacecraft at the end of its mission sounds like a simple enough job,” says Gaia Spacecraft Operator Tiago Nogueira. “But spacecraft really don’t want to be switched off.”

“Gaia was designed to withstand failures such as radiation storms, micrometeorite impacts or a loss of communication with Earth. It has multiple redundant systems that ensured it could always reboot and resume operations in the event of disruption.”

“We had to design a decommissioning strategy that involved systematically picking apart and disabling the layers of redundancy that have safeguarded Gaia for so long, because we don’t want it to reactivate in the future and begin transmitting again if its solar panels find sunlight.”

On 27 March 2025, the Gaia control team ran through this series of passivation activities. One final use of Gaia’s thrusters moved the spacecraft away from L2 and into a stable retirement orbit around the Sun that will minimise the chance that it comes within 10 million km Earth for at least the next century. The team then safely deactivated and switched off the spacecraft’s instruments and subsystems one by one, before deliberately corrupting its onboard software. The communication subsystem and the central computer were the last to be deactivated.

Gaia’s final transmission to ESOC mission control marked the conclusion of an intentional and carefully orchestrated farewell to a spacecraft that has tirelessly mapped the sky for over a decade.

The final commands have been sent to Gaia. This is the last time that the spacecraft will ever hear from its team on Earth. The final commands include those to shut down the spacecraft's communication systems and central computer.
 

A lasting legacy

 

Though Gaia itself has now gone silent, its contributions to astronomy will continue to shape research for decades. Its vast and expanding data archive remains a treasure trove for scientists, refining knowledge of galactic archaeology, stellar evolution, exoplanets and much more.

A workhorse of galactic exploration, Gaia has charted the maps that future explorers will rely on to make new discoveries. The star trackers on ESA’s Euclid spacecraft use Gaia data to precisely orient the spacecraft. ESA’s upcoming Plato mission will explore exoplanets around stars characterised by Gaia and may follow up on new exoplanetary systems discovered by Gaia.

The Gaia control team also used the spacecraft’s final weeks to run through a series of technology tests. The team tested Gaia’s micro propulsion system under different challenging conditions to examine how it had aged over more than ten years in the harsh environment of space. The results may benefit the development of future ESA missions relying on similar propulsion systems, such as the LISA mission.

Forever in Gaia’s memory

 

The Gaia spacecraft holds a deep emotional significance for those who worked on it. As part of its decommissioning, the names of around 1500 team members who contributed to its mission were used to overwrite some of the back-up software stored in Gaia’s onboard memory.

Personal farewell messages were also written into the spacecraft’s memory, ensuring that Gaia will forever carry a piece of its team with it as it drifts through space.

As Gaia Mission Manager Uwe Lammers put it: “We will never forget Gaia, and Gaia will never forget us.”

The fate of the universe hinges on the balance between matter and dark energy: the fundamental ingredient that drives its accelerating expansion. New results from the Dark Energy Spectroscopic Instrument (DESI) collaboration use the largest 3D map of our universe ever made to track dark energy’s influence over the past 11 billion years. Researchers see hints that dark energy, once thought to be a “cosmological constant,” might be evolving over time in unexpected ways.
 

DESI is an international experiment with more than 900 researchers from over 70 institutions around the world and is managed by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). The collaboration shared their findings today in multiple papers that will be posted on the online repository arXiv and in a presentation at the American Physical Society’s Global Physics Summit in Anaheim, California.

“The obtained results are very interesting”, says Andreu Font-Ribera, a scientist at the Institut de Física d’Altes Energies (IFAE) and a member of the DESI team that has developed this study. “It seems that we are on the verge of a change of paradigm for our models of the Universe, and this is very exciting”.

Taken alone, DESI’s data are consistent with our standard model of the universe: Lambda CDM (where CDM is cold dark matter and lambda represents the simplest case of dark energy, where it acts as a cosmological constant). However, when paired with other measurements, there are mounting indications that the impact of dark energy may be weakening over time and other models may be a better fit. Those other measurements include the light leftover from the dawn of the universe (the cosmic microwave background or CMB), exploding stars (supernovae), and how light from distant galaxies is warped by gravity (weak lensing).

“In my opinion, it is still too early to claim categorically that we have discovered an evolving dark energy”, says Eusebio Sánchez, scientific researcher at CIEMAT, who has participated in the data analysis. “However, the fact that different independent projects are observing similar results make this situation especially interesting”.

So far, the preference for an evolving dark energy has not risen to “5 sigma,” the gold standard in physics that represents the threshold for a discovery. However, different combinations of DESI data with the CMB, weak lensing, and supernovae sets range from 2.8 to 4.2 sigma. (A 3-sigma event has a 0.3% chance of being a statistical fluke, but many 3-sigma events in physics have faded away with more data.) The analysis used a technique to hide the results from the scientists until the end, mitigating any unconscious bias about the data.

“These new data could be indicating that the Universe is more complicated that we thought so far”, comments Sergi Novell Masot, PhD student at ICCUB and a member of the Institut d’Estudis Espacials de Catalunya (IEEC),  who has recently published a complementary study of the DESI maps. ”However, before obtaining final conclusions,  we need to understand the supernovae and CMB data that combined with DESI results seem to point towards this direction”.

DESI is one of the most extensive surveys of the cosmos ever conducted. The state-of-the-art instrument can capture light from 5,000 galaxies simultaneously.
 

Spanish groups had an important role in its construction and are collaborating in its operation. DESI is mounted on the U.S. National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona. The experiment is now in its fourth of five years surveying the sky, with plans to measure roughly 50 million galaxies and quasars (extremely distant yet bright objects with black holes at their cores) by the time the project ends.

The new analysis uses data from the first three years of observations and includes nearly 15 million of the best measured galaxies and quasars. It’s a major leap forward, improving the experiment’s precision with a dataset that is more than double what was used in DESI’s first analysis, which also hinted at an evolving dark energy.

“If it is confirmed, this would be one of the most important results in cosmology of the last few decades, since it opens the door to new ideas beyond the standard model, ΛCDM», comments Juan García-Bellido, a researcher at the IFT-UAM/CSIC, who has collaborated in this measurement. “If results get higher significance with future measurements we could explore ideas like new theories of gravitation or quintessence, that predict an evolving acceleration for the Universe expansion”.

DESI tracks dark energy’s influence by studying how matter is spread across the universe. Events in the very early universe left subtle patterns in how matter is distributed, a feature called baryon acoustic oscillations (BAO). That BAO pattern acts as a standard ruler, with its size at different times directly affected by how the universe was expanding. Measuring the ruler at different distances shows researchers the strength of dark energy throughout history. DESI’s precision with this approach is the best in the world.

“We are in an very exciting moment, since for a long time we thought the Universe behaves in a certain way, but now, with more precise data, we realize that there are aspects that we do not fully understand yet”, says Laura Casas, a PhD student at the Institut de Física d’Altes Energies (IFAE) in Barcelona, who has led the validation of the Lyman-alpha forest analysis, the imprint of intervening clouds of hydrogen in the light from distant quasars. “Although there is still much to research, the hints about evolving dark energy are a fascinating finding”.

The collaboration will soon begin work on additional analyses to extract even more information from the current dataset, and DESI will continue collecting data. Other experiments coming online over the next several years will also provide complementary datasets for future analyses. 

“The observational results we are obtaining about the evolution of the Universe open a wide spectrum for possible theories that can explain these observations”, comments Francisco Javier Castander, a researcher at the ICE-CSIC and IEEC, who has contributed to the experiment. “Independently of the dark energy nature, its properties will determine the Universe’s future. It is very rewarding to verify that the instrument we have built  allows us to make detailed observations of the sky, and then answer one of the biggest questions that humanity has ever asked”.

Videos discussing the experiment’s new analysis are available on the DESI YouTube channel. Alongside unveiling its latest dark energy results at the APS meeting today, the DESI collaboration also announced that its Data Release 1 (DR1) is now available for anyone to explore. With information on millions of celestial objects, the dataset will support a wide range of astrophysical research by others, in addition to DESI’s cosmology goals. 

The Dark Energy Spectroscopic Instrument Collaboration

DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science national user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.

The DESI collaboration is honored to be permitted to conduct scientific research on I’oligam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.

The spanish institutions that participate in DESi are the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), the Instituto de Ciencias del Espacio (ICE-CSIC/IEEC), the Institut de Ciències del Cosmos de la Universitat de Barcelona (ICCUB), the Institut de Física d'Altes Energies (IFAE), the Instituto de Física Teórica (IFT-UAM/CSIC), the Instituto de Astrofísica de Andalucía (IAA) and the Instituto de Astrofísica de Canarias (IAC).

Contact persons

CIEMAT: Dr. Eusebio Sánchez, Investigador Científico, eusebio.sanchez@ciemat.es
ICCUB-IEEC: Dr. Héctor Gil, Investigador Ramón y Cajal, hectorgil@icc.ub.edu
ICE-CSIC/IEEC: Dr. Francisco Castander, Profesor de Investigación, fjc@ice.csic.es
IFAE:    Dr. Andreu Font-Ribera, Investigador Ramón y Cajal, afont@ifae.es
IFT-UAM/CSIC: Dr. Juan García-Bellido, Catedrático, juan.garciabellido@uam.es

Distributed by the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), the Institut de Ciències del Cosmos de la Universitat de Barcelona (ICCUB), the Instituto de Ciencias del Espacio (ICE-CSIC), the Institut d’Estudis Espacials de Catalunya (IEEC), the Institut de Física d’Altes Energies (IFAE) and the Instituto de Física Teórica (UAM-CSIC) on behalf of the DESI Collaboration.
 

An international research team with the participation of Núria Miret-Roig, researcher from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), has discovered that the Solar System traversed the Orion star-forming complex, a component of the Radcliffe Wave galactic structure, approximately 14 million years ago. This journey through a dense region of space could have compressed the heliosphere, the protective bubble surrounding our solar system, and increased the influx of interstellar dust, potentially influencing Earth's climate and leaving traces in geological records. The findings, published in Astronomy & Astrophysics, offer a fascinating interdisciplinary link between astrophysics, paleoclimatology, and geology.

The Solar System's journey around the Milky Way's center takes it through varying galactic environments. "Imagine it like a ship sailing through varying conditions at sea," explains Efrem Maconi, lead author and doctoral student at the University of Vienna. "Our Sun encountered a region of higher gas density as it passed through the Radcliffe Wave in the Orion constellation."

Using data from the European Space Agency's (ESA) Gaia mission and spectroscopic observations, the team pinpointed the Solar System's passage through the Radcliffe Wave in the Orion region about 14 million years ago. “We crossed the Orion complex while hundreds of stars were forming in that region, within  star clusters such as NGC 1977, NGC 1980, and NGC 1981,” says Núria Miret-Roig, a participant in the project and a current researcher of the University of Barcelona. “This is a very well-known region, visible with the naked eye in the winter sky of the Northern Hemisphere and the summer sky of the Southern Hemisphere”. 

"This discovery builds upon our previous work identifying the Radcliffe Wave," says João Alves, professor of astrophysics at the University of Vienna and co-author of the study. The Radcliffe Wave is a vast, thin structure of interconnected star-forming regions, including the renowned Orion complex, which the Sun traversed, as established in this study.

The increased dust from this galactic encounter could have had several effects. It may have penetrated the Earth's atmosphere, potentially leaving traces of radioactive elements from supernovae in geological records. "While current technology may not be sensitive enough to detect these traces, future advancements could make it possible," Alves suggests. 

The team's research indicates the Solar System's passage through the Orion region occurred between approximately 18.2 and 11.5 million years ago, with the most likely time between 14.8 and 12.4 million years ago. This timeframe aligns well with the Middle Miocene Climate Transition, a significant shift from a warm variable climate to a cooler climate, leading to the establishment of a continental-scale prototype Antarctic ice sheet configuration. While the study raises the possibility of a link between the past traverse of the solar system through its galactic neighborhood and Earth’s climate via interstellar dust, the authors emphasize that a causal connection requires further investigation. 

Not comparable to the current human-made climate change

“While the underlying processes responsible for the Middle Miocene Climate Transition are not entirely identified, the available reconstructions suggest that a long-term decrease in the atmospheric greenhouse gas carbon dioxide concentration is the most likely explanation, although large uncertainties exist. However, our study highlights that interstellar dust related to the crossing of the Radcliffe Wave might have impacted Earth’s climate and potentially played a role during this climate transition. To alter the Earth’s climate the amount of extraterrestrial dust on Earth would need to be much bigger than what the data so far suggest,” says Maconi. “Future research will explore the significance of this contribution. It’s crucial to note that this past climate transition and current climate change are not comparable since the Middle Miocene Climate Transition unfolded over timescales of several hundred thousand years. In contrast, the current global warming evolution is happening at an unprecedented rate over decades to centuries due to human activity.”
This study is important because it adds a small puzzle piece to the recent history of the Solar System, helping to place it in the context of the Milky Way. “We are inhabitants of the Milky Way,” says Alves, “The European Space Agency’s Gaia Mission has given us the means to trace our recent route in the Milky Way’s interstellar sea, allowing astronomers to compare notes with geologists and paleoclimatologists. It’s very exciting.” In the future, the team led by João Alves plans to study in more detail the Galactic environment encountered by the Sun while sailing through our Galaxy.

Reference: 
Maconi, E., J. Alves, C. Swiggum, S. Ratzenböck, J. Großschedl, P. Köhler, N. Miret-Roig, et al. “The Solar System’s Passage through the Radcliffe Wave during the Middle Miocene.” Astronomy & Astrophysics 694 (February 1, 2025): A167. https://doi.org/10.1051/0004-6361/202452061.
 

Traditional black holes -as predicted by Einstein's General Relativity- contain singularities, that is, points where the laws of physics break down. Identifying how singularities are resolved in the context of quantum gravity is one of the fundamental problems in theoretical physics. Now researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) have described the creation of regular black holes purely from gravitational effects, without the need for exotic matter indicated by previous models.

This discovery, published in the journal Physics Letters B, offers a promising pathway towards understanding the quantum nature of gravity and the true structure of spacetime.

Black holes without singularities

Exotic matter refers to a type of matter that has unusual properties not found in ordinary matter. It often has a negative energy density, creating repulsive gravitational effects, and can violate certain energy conditions in general relativity. Exotic matter is largely theoretical and has not been observed in nature, but it is used in models to explore concepts like wormholes, faster-than-light travel, and resolution of black hole singularities.

The new study demonstrates that mathematically, an infinite series of higher-order gravitational corrections can eliminate these singularities, resulting in "regular" black holes. Unlike previous models that required exotic matter to achieve regular black holes, this research shows that pure gravity alone, with no additional matter fields, can produce these singularity-free solutions. This is a significant shift from earlier theories and simplifies the conditions needed for regular black holes.

“The beauty of our construction is that it only relies on modifications of the Einstein’s equations that are naturally predicted by quantum gravity. No other ingredients are required”, says Pablo Cano, from the Department of Quantum Physics and Astrophysics of the Faculty of Physics and the ICCUB.

The theories developed by the researchers are applicable in any spacetime dimension greater than or equal to five. “The reason for considering higher spacetime dimensions is purely technical” says Pablo Cano as it allows them to “reduce the mathematical complexity of the problem” - he adds. Nevertheless, the researchers expect that “the same conclusions should apply in our four dimensional spacetime”.

Moreover, the expert Robie Hennigar (UB-ICCUB) says that ”most scientists agree that the singularities of general relativity must be ultimately resolved, though we know very little about how this process could be accomplished. Our work provides the first mechanism to accomplish this in a robust way, albeit under certain symmetry assumptions.”

“It’s not clear how nature prevents the formation of singularities in our Universe, but we hope our model will help us to develop an understanding of this process” Says Henningar.

Exploring findings in astrophysical scenarios

The study also explores the thermodynamic properties of these regular black holes, showing that they satisfy the first law of thermodynamics. The theories developed by the researchers provide a robust framework for understanding black hole thermodynamics in a completely universal and unambiguous way. This consistency adds to the credibility and potential applicability of the findings.

The researchers plan to extend their work to four-dimensional spacetime and explore the implications of their findings in various astrophysical scenarios. They also aim to investigate the stability and potential observational signatures of these regular black holes.

“These theories not only predict singularity-free black holes, they also allow us to understand how these objects form and what is the fate of matter that falls inside a black hole. We are already working on these questions, finding really exciting results.” concludes Pablo Cano.

Reference article:

Bueno, Pablo; Cano, Pablo A; Hennigar, Robie A. «Regular black holes from pure gravity». Physics Letters B, February 2025. DOI: 10.1016/j.physletb.2025.139260

Last starlight for ground-breaking Gaia

The European Space Agency’s Milky Way-mapper Gaia has completed the sky-scanning phase of its mission, racking up more than three trillion observations of about two billion stars and other objects over the last decade to revolutionise the view of our home galaxy and cosmic neighbourhood.

Launched on 19 December 2013, Gaia’s fuel tank is now approaching empty – it uses about a dozen grams of cold gas per day to keep it spinning with pinpoint precision. But this is far from the end of the mission. Technology tests are scheduled for the weeks ahead before Gaia is moved to its ‘retirement’ orbit, and two massive data releases are tabled for around 2026 and the end of this decade, respectively.

“Today marks the end of science observations and we are celebrating this incredible mission that has exceeded all our expectations, lasting for almost twice its originally foreseen lifetime,” says ESA Director of Science Carole Mundell.

“The treasure trove of data collected by Gaia has given us unique insights into the origin and evolution of our Milky Way galaxy, and has also transformed astrophysics and Solar System science in ways that we are yet to fully appreciate. Gaia built on unique European excellence in astrometry and will leave a long-lasting legacy for future generations."

“After 11 years in space and surviving micrometeorite impacts and solar storms along the way, Gaia has finished collecting science data. Now all eyes turn towards the preparation of the next data releases,” says Gaia Project Scientist Johannes Sahlmann.

“I am thrilled with the performance of this incredible mission, and excited about the discoveries that await us.”

Researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) have played a crucial role in the Gaia mission since the very beginning. 

"The Gaia team at the University of Barcelona has been working on the mission since its inception around 1997." says Xavier Luri, director of the ICCUB and member of the Gaia UB team. "Since then, they have participated in all its phases, from defining the scientific case and industrial design to data processing and scientific exploitation. Now, although Gaia is ending its observations, several years of work remain to fully process all the data collected over these years and publish two additional data releases (DR4 and DR5)."

Gaia delivers best Milky Way map

Gaia has been charting the positions, distances, movements, brightness changes, composition and numerous other characteristics of stars by monitoring them with its three instruments many times over the course of the mission.

This has enabled Gaia to deliver on its primary goal of building the largest, most precise map of the Milky Way, showing us our home galaxy like no other mission has done before.

As such, we now also have the best reconstructed view of how our galaxy might look to an outside observer. This new artist impression of the Milky Way incorporates Gaia data from a multitude of papers over the past decade.

“It contains major changes from previous models, because Gaia has changed our impression of the Milky Way. Even basic ideas have been revised, such as the rotation of our galaxy’s central bar, the warp of the disc, the detailed structure of spiral arms, and interstellar dust near the Sun,” says Stefan Payne-Wardenaar, scientific visualiser at the Max Planck Institute for Astronomy, Germany.

“Still, the distant parts of the Milky Way remain educated guesses based on incomplete data. With further Gaia data releases our view of the Milky Way will become even more accurate.”

Discovery machine of the decade

Gaia’s repeated measurements of stellar distances, motions and characteristics are key to performing ‘galactic archeology’ on our Milky Way, revealing missing links in our galaxy’s complex history to help us learn more about our origins. From detecting ‘ghosts’ of other galaxies and multiple streams of ancient stars that merged with the Milky Way in its early history, to finding evidence for an ongoing collision with the Sagittarius dwarf galaxy today, Gaia is rewriting the Milky Way’s history and making predictions about its future.

In the process of scanning the stars in our own galaxy, Gaia has also spotted other objects, from asteroids in our Solar System backyard to galaxies and quasars – the bright and active centres of galaxies powered by supermassive black holes – outside our Milky Way.

For example, Gaia has provided pinpoint precision orbits of more than 150 000 asteroids, and has such high-quality measurements as to uncover possible moons around hundreds of them. It has also created the largest three-dimensional map of about 1.3 million quasars, with the furthest shining bright when the Universe was only 1.5 billion years old.

Gaia has also discovered a new breed of black hole, including one with a mass of nearly 33 times the mass of the Sun, hiding in the constellation Aquila, less than 2000 light-years from Earth – the first time a black hole of stellar origin this big has been spotted within the Milky Way.

“It is impressive that these discoveries are based only on the first few years of Gaia data, and many were made in the last year alone. Gaia has been the discovery machine of the decade, a trend that is set to continue,” says Anthony Brown, Chair of the Gaia Data Processing and Analysis Consortium (DPAC) and based at Leiden University in the Netherlands.

Warning! More ground-breaking science ahead

The Gaia scientific and engineering teams are already working full steam on the preparations for Gaia Data Release 4 (DR4), expected in 2026. The data volume and quality improves with every release and Gaia DR4, with an expected 500 TB of data products, is no exception. Furthermore, it will cover the mission’s first 5.5 years, corresponding to the length of the originally foreseen duration of the mission.

“This is the Gaia release the community has been waiting for, and it’s exciting to think this only covers half of the collected data,” says Antonella Vallenari, Deputy Chair of DPAC based at the Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory of Padua, Italy.

“Even though the mission has now stopped collecting data, it will be business as usual for us for many years to come as we make these incredible datasets ready for use.”

 Gaia DR4 is set to expand its binary star catalogue, the largest such catalogue to date. Gaia has a unique ability to tease out the tiny motions of pairs of celestial objects orbiting close to each other, and has already spotted previously hidden companions around bright stars.

Incidentally, Gaia’s last targeted observation, on 10 January, was of binary pair 61 Cygni. This iconic star attracted the attention of 19th-century astronomers to yield some of the first proper motion and parallax measurements, techniques used by Gaia on some two billion stars.

Gaia’s exoplanet discoveries are also set to increase with the forthcoming datasets thanks to the longer timeframe of observations making it much easier to spot ‘wobbling’ stars gently tugged by orbiting planets.

“Over the next months we will continue to downlink every last drop of data from Gaia, and at the same time the processing teams will ramp up their preparations for the fifth and final major data release at the end of this decade, covering the full 10.5 years of mission data,” says Rocio Guerra, Gaia Science Operations Team Leader based at ESA’s European Space Astronomy Centre (ESAC) near Madrid in Spain.

“This will conclude an incredible coordinated effort between hundreds of experts across the science operations centre here at ESAC, the mission operations team flying Gaia from ESA’s European Space Operations Centre in Germany, and the huge consortium of data processing specialists, who have together ensured the smooth running of this beautiful mission for so long.”

Gaia’s retirement plan

While today marks the end of science observations, a short period of technology testing now begins. The tests have the potential to further improve the Gaia calibrations, learn more about the behaviour of certain technology after ten years in space, and even aid the design of future space missions.

After several weeks of testing, Gaia will leave its current orbit around Lagrange point 2, 1.5 million km from the Earth in the direction away from the Sun, to be put into its final heliocentric orbit, far away from Earth’s sphere of influence. The spacecraft will be passivated on 27 March 2025, to avoid any harm or interference with other spacecraft.

Wave farewell to Gaia

During the technology tests Gaia’s orientation will be changed, meaning it will temporarily become several magnitudes brighter, making observations through small telescopes a lot easier (it won’t be visible to the naked eye). A guide to locating Gaia has been set up here, and amateur astronomers are invited to share their observations.

“Gaia will treat us with this final gift as we bid farewell, shining among the stars ahead of its well-earned retirement,” concludes Uwe Lammers, Gaia Mission Manager.

“It’s a moment to celebrate this transformative mission and thank all of the teams for more than a decade of hard work operating Gaia, planning its observations, and ensuring its precious data are returned smoothly to Earth.”

The SKA Observatory (Square Kilometre Array, SKAO) has entrusted Compoxi (a Girona-based company specialising in the design and production of composite materials) and EOSOL (an international company based in Navarra specialising in engineering services) to build a large number of sub-reflectors for the mid-frequency telescope ‘SKA-Mid’, currently under construction in South Africa.

SKAO is considered one of the largest scientific engineering projects of the 21st century. Countries from five continents are collaborating in the construction of the two largest radio telescope arrays on Earth: on the one hand, in Australia, the low frequency array, known as ‘SKA-Low’, will have 131,072 antennas spread over 74 km; on the other hand, in South Africa, ‘SKA-Mid’ will have 197 parabolic antennas (incorporating the 64 of the ‘MeerKAT’ radio telescope) spread over 150 km. Because of the size and number of antennas, SKA will represent a significant leap in resolution, sensitivity and observing speed over other radio telescopes, allowing more parts of the universe to be seen in greater detail than ever before. The array design and processing power will also allow radio astronomers around the world to study different parts of the cosmos simultaneously.

The Institute of Space Studies of Catalonia (IEEC — Institut d’Estudis Espacials de Catalunya) collaborates with the SKA Observatory with researchers at the Institute of Space Sciences (ICE-CSIC) and the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), who participate in different science working groups. Some of the topics covered include the study of the cradle of life (the formation of planets, etc.), our galaxy, cosmic magnetism, pulsars or transient events.

Compoxi is part of the NewSpace Lab, the reference point for NewSpace sector facilities in Catalonia, an initiative of the Government of Catalonia and the IEEC to facilitate the use of the various infrastructures. With the participation of Compoxi in the construction of the sub-reflectors, the Catalan contribution to the observatory extends to the technical part from the private sector, which shows the great potential of the space sector in the region.

The sub-reflector is one of the critical parts of the satellite dish, which serves to concentrate the signals collected by the main reflector. Each sub-reflector is a 4.5-metre structure made of composite material and metallised to achieve the electromagnetic and mechanical properties required for the project.

“The ‘SKA-Mid’ subreflector is a technically challenging design; the surface requires high levels of precision and is a critical optical component to accurately reflect the faint astronomical signal received,” says SKAO Dish project manager Mark Harman. “It also has to be very rigid to withstand the environmental conditions. We are very impressed with the capabilities of EOSOL and COMPOXI and are excited to be working on this project as we start to prepare for construction activities next year.”

SKAO is part of a new era in the history of the exploration of the Universe. It will aim to answer fundamental questions in astrophysics, while bringing benefits to society through technological innovations and collaborations between continents and scientific communities. As for the IEEC, the following ICE-CSIC researchers participate in a working group of the project: Josep Miquel Girart, Ciska Kemper, Álvaro Sánchez Monge, Daniele Viganò, Francesco Coti Zelati, Nanda Rea, Laura Tolós, Diego Torres, Mar Mezcua and Josep Maria Trigo. From the ICCUB, the researcher Gemma Busquet is participating.

The radio telescopes are currently in the construction phase; the first scientific verifications are expected to begin with partial arrays at the end of 2026, and the scientific capabilities will increase as construction continues over the next six years.

Links

• IEEC
• ICE-CSIC
• ICCUB
• Compoxi
• EOSOL
• SKAO

Using the set of first-light observations from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) wide-field spectrograph, a team of more than 50 astronomers, led by Dr Marina Arnaudova at the University of Hertfordshire, has presented the first WEAVE scientific results on Stephan’s Quintet.
This state-of-the-art wide-field spectrograph is a 20-million Euro project that brings together leading experts from around the world. WEAVE is set to revolutionise our understanding of the Universe, offering unprecedented detail, as demonstrated in this new study of Stephan’s Quintet.

Stephan's Quintet, also known as the Hickson Compact Group 92, is a nearby galaxy group that consists of five galaxies (NGC 7317, NGC 7318a, NGC 7318b, NGC 7319 and NGC 7320c). Ever since its discovery in 1877, it has captivated astronomers, particularly because it represents a galactic crossroad where past collisions between galaxies have left behind a complex field of debris.

“Dynamical activity in this galaxy group has now been reawakened by NGC 7318b, a galaxy smashing through it at an incredible speed of over 2 million miles per hour (3.2 million kilometres per hour), leading to an immensely powerful shock, much like a sonic boom from a jet fighter”, says Dr Arnaudova. This system thus presents an ideal laboratory to understand the chaotic and often violent relationship between galaxies, and as such was the focus of the first-light observations by the WEAVE Large Integral Field Unit (LIFU).

Published in the Monthly Notices of the Royal Astronomical Society (MNRAS), Dr Arnaudova and her team provide a new insight into the large-scale shock front. By combining data from WEAVE's LIFU with other cutting-edge instruments such as the Low Frequency Array (LOFAR), the Very Large Array (VLA), and the James Webb Space Telescope (JWST), they have found a previously undiscovered dual nature of the shock.

As the shock moves through pockets of cold gas, it travels at hypersonic speeds—several times the speed of sound—powerful enough to rip apart electrons from atoms, leaving behind a glowing trail of charged gas, as seen with WEAVE. However, when the shock passes through the surrounding hot gas, it becomes much weaker. Instead of causing significant disruption, the weak shock compresses the hot gas, resulting in radio waves that are picked up by radio telescopes like LOFAR.

The WEAVE, a new generation spectrograph

The WEAVE spectrograph uses optical fibres to collect light from celestial objects and transmits it to a spectrograph that separates the light according to its different wavelengths. It can work at two different spectral resolutions, which are used to measure the speeds of objects in the line of sight (using the Doppler effect) and to determine their chemical composition. The versatility of WEAVE is one of its main strengths. While the LIFU mode contains hundreds of fibres in a compact distribution, essential for imaging extended areas of the sky, in the MOS mode about a thousand individual fibres can be placed (by two robots) to simultaneously collect light from stars, galaxies or quasars. During the first five years of operation, spectra of millions of individual stars and galaxies are expected, a goal that can be achieved thanks to the WEAVE spectrograph's ability to observe so many bodies at once.

The Catalan contribution to the WEAVE spectrograph

This project involves scientists from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Technical University of Catalonia (UPC). The Institute for Space Studies of Catalonia (IEEC) is taking part with researchers from the ICCUB and UPC units. The Catalan institutions have worked, from the beginning of the project, on the definition of the scientific objectives and the selection of the objects to be observed —from stars in various evolutionary phases to star clusters— as well as in the sampling of quasars, extremely bright and very distant active nuclei galaxies. Specifically, one ICCUB-IEEC member, Mercè Romero-Gómez, and one from the UPC, Roberto Raddi, are members of the international working groups on young stars, galactic archaeology and white dwarfs that make up the team of scientists responsible for planning the observations. Teresa Antoja (ICCUB) and Ignasi Pérez-Ràfols (UPC) co-lead the research teams responsible for galactic disc dynamics and quasars, respectively.
Mercè Romero-Gómez, from the Institute of Cosmos Sciences (ICCUB-IEEC), says: "After years of preparation, we have been able to obtain the first spectra with the Large Integral Field Unit of WEAVE from the Stephan’s quintet group of galaxies. The quality of the spectra has allowed to reassess the dynamical processes happening in this well-known set of galaxies”. In the following year, data coming from the Multi-Object Spectrograph will allow to assess the dynamics of our own Galaxy, together with the astrometric and spectroscopic data from Gaia (ESA).

Roberto Raddi and Ignasi Pérez-Ràfols, commenting on the contribution of the Polytechnic University of Catalonia, say: "Our teams will contribute to the study of some 100,000 white dwarfs previously identified by Gaia, and discover the secrets behind the last evolutionary phases of Sun-like stars, and with the identification of 450,000 quasars, the most distant and bright active galactic nuclei in the universe".

Research paper

M. I. Arnaudova et al., 2024, "WEAVE First Light observations: Origin and Dynamics of the Shock Front in Stephan's Quintet", MNRAS.

More information

"Inauguration of WEAVE", ING Press Release, 31 October 2023.

"WEAVE First Light", ING Press Release, 12 December 2022.

"WEAVE spectrograph begins study of galaxy formation and evolution", ICCUB Press Release, 12 December 2022.

Jin S., et al., 2024, "The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation", MNRAS, 530, 2688. Paper.

Gravity has shaped our cosmos. Its attractive influence turned tiny differences in the amount of matter present in the early universe into the sprawling strands of galaxies we see today. A new study using data from the Dark Energy Spectroscopic Instrument (DESI) has traced how this cosmic structure grew over the past 11 billion years, providing the most precise test to date of gravity at very large scales. 

DESI is an international collaboration of more than 900 researchers from over 70 institutions around the world and is managed by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). In their new study, DESI researchers found that gravity behaves as predicted by Einstein’s theory of general relativity. The result validates our leading model of the universe and limits possible theories of modified gravity, which have been proposed as alternative ways to explain unexpected observations – including the accelerating expansion of our universe that is typically attributed to dark energy.

"These data allow us to study how fast the largest structures of the universe have formed, and thus set limits in the Einstein General Relativity theory at cosmological scales, much larger than the solar system scales" explains Héctor Gil Marín from the Institute of Cosmos Sciences of the University of Barcelona and member of the Institute of Space Studies of Catalonia who has co-lead this new analysis. "So far the results perfectly fit the predictions by the Einstein General Relativity Theory".

This simulation shows how more or less gravity affects the positions of galaxies that we observe, changing how they are clustered in a galaxy map. Because different models of gravity predict different clustering of galaxies, DESI researchers can compare observations with simulations to test gravity at cosmic scales.
Credit: Claire Lamman and Michael Rashkovetskyi / DESI collaboration

The study also provided new upper limits on the mass of neutrinos, the only fundamental particles whose masses have not yet been precisely measured. Previous neutrino experiments found that the sum of the masses of the three types of neutrinos should be at least 0.059 eV/c². (For comparison, an electron has a mass of about 511,000 eV/c².) DESI’s results indicate that the sum should be less than 0.071 eV/c², leaving a narrow window for neutrino masses.

The DESI collaboration shared their results in several papers posted to the online repository arXiv today. The complex analysis used nearly 6 million galaxies and quasars and lets researchers see up to 11 billion years into the past. With just one year of data, DESI has made the most precise overall measurement of the growth of structure, surpassing previous efforts that took decades to make. 

In this 360-degree video, take an interactive flight through millions of galaxies mapped using coordinate data from DESI. 
Credit: Fiske Planetarium, CU Boulder and DESI collaboration
 

Today’s results provide an extended analysis of DESI’s first year of data, which in April made the largest 3D map of our universe to date and revealed hints that dark energy might be evolving over time. The April results looked at a particular feature of how galaxies cluster known as baryon acoustic oscillations (BAO). The new analysis, called a “full-shape analysis,” broadens the scope to extract more information from the data, measuring how galaxies and matter are distributed on different scales throughout space. The study required months of additional work and cross-checks. Like the previous study, it used a technique to hide the result from the scientists until the end, mitigating any unconscious bias. 

«The results of the first year of DESI data are stunning», says Eusebio Sánchez, a researcher at CIEMAT who has contributed to the data analysis. «And this is only the beginning, the project is taking more data that will allow us to improve a lot the current understanding of gravity and dark energy».

DESI is a state-of-the-art instrument that can capture light from 5,000 galaxies simultaneously. It was constructed and is operated with funding from the DOE Office of Science. DESI is mounted on the U.S. National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (a program of NSF NOIRLab). The experiment is now in its fourth of five years surveying the sky and plans to collect roughly 40 million galaxies and quasars by the time the project ends.

The collaboration is currently analyzing the first three years of collected data and expects to present updated measurements of dark energy and the expansion history of our universe in spring 2025. DESI’s expanded results released today are consistent with the experiment’s earlier preference for an evolving dark energy, adding to the anticipation of the upcoming analysis. 

«The distribution of galaxies suggests the presence of dark matter and dark energy, both of which remain largely mysterious to us», says Hui Kong, a postdoctoral researcher at IFAE who worked on the curation of the galaxy catalogs. «However, the precise measurements provided by DESI offer promising insights into these fundamental questions about the universe».

DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.

The DESI collaboration is honored to be permitted to conduct scientific research on I’oligam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.

The institutions participating in DESI include the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), the Instituto de Ciencias del Espacio (ICE-CSIC/IEEC), the Institut de Ciències del Cosmos at the Universitat de Barcelona (ICCUB), the Institut de Física d'Altes Energies (IFAE), the Instituto de Física Teórica (IFT-UAM/CSIC), the Instituto de Astrofísica de Andalucía (IAA) and the Instituto de Astrofísica de Canarias (IAC).
The full list of participating institutions and more information about DESI is available at: [https://www.desi.lbl.gov](https://www.desi.lbl.gov).