A five-year quest to map the universe and unravel the mysteries of “dark energy” is beginning officially today, May 17, at Kitt Peak National Observatory near Tucson, Arizona, USA. To complete its quest, the Dark Energy Spectroscopic Instrument (DESI) will capture and study the light from tens of millions of galaxies and other distant objects in the universe.

By gathering light from some 30 million galaxies, project scientists say DESI will help them construct a 3D map of the universe with unprecedented detail. The data will help them better understand the repulsive force associated with “dark energy” that drives the acceleration of the expansion of the universe across vast cosmic distances.

What sets DESI apart from previous sky surveys? “DESI will allow us to see an order of magnitude more galaxies than ever before, and study the evolution of the Universe from 11 billion years ago to the present day”, explained Héctor Gil-Marín, a scientist at Institut de Ciències del Cosmos at the University of Barcelona (ICCUB) and at the Institute of Space Studies of Catalonia (IEEC), that will co-lead the first analysis of the galaxy maps. The DESI telescope collects light, or spectra, from galaxies and quasars, which get us their recession velocity. “We know that the farther the object is from us, the higher its recession velocity is, which allows us to build a 3D map of the universe”, Gil-Marín explained.

“DESI is the front runner of a new generation of instruments around the globe that will study dark energy from different angles,” said Andreu Font-Ribera, a cosmologist at Institut de Física d’Altes Energies (IFAE) that will co-lead the first analysis of the most distant quasars. He said the scientific program will allow researchers to address with precision two primary questions: what is dark energy; and the degree to which gravity follows the laws of general relativity, which form the basis of our understanding of the cosmos. “It has taken 10 years of effort, from the instrument design to this moment, when DESI starts collecting the data that is going to revolutionize our understanding of the Universe” says Violeta Gonzalez-Perez, a scientist at Universidad Autónoma de Madrid (UAM) that is one of the coordinators for developing computer simulations of what DESI will observe.

The disk of the Andromeda Galaxy (M31), which spans more than 3 degrees, is targeted by a single DESI pointing, represented by the large, pale green, circular overlay. The smaller circles within this overlay represent the regions accessible to each of the 5000 DESI robotic fiber positioners. In this sample, the 5000 spectra that were simultaneously collected by DESI include not only stars within the Andromeda Galaxy, but also distant galaxies and quasars. The example DESI spectrum that overlays this image is of a distant quasar (QSO) 11 billion years old. Credit: DESI collaboration and DESI Legacy Imaging Surveys

The formal start of DESI’s five-year survey follows a four-month trial run of its custom instrumentation that captured four million spectra of galaxies – more than the combined output of all previous spectroscopic surveys.

The DESI instrument resides at the retrofitted Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a program of the National Science Foundation’s (NSF) NOIRLab. The instrument includes new optics that increase the field of view of the telescope and includes 5,000 robotically controlled optical fibers to gather spectroscopic data from an equal number of objects in the telescope’s field of view.

“What is special about DESI is not so much the telescope, but the instrument” says Otger Ballester, an engineer at IFAE who has been part of the team developing the guiding, focusing and alignment cameras for DESI, one of the Spanish contributions to the project. In fact, the instrument “can simultaneously gather light from 5,000 different objects and obtain their spectra in just 20 minutes” Ballester said. As the telescope is moved into a target position, the optical fibers align to collect light from galaxies as it is reflected off the telescope mirror. From there, the light is fed into a bank of spectrographs and CCD cameras for further processing and study. On a good night, DESI collects spectra from some 150,000 objects.

Photo of a small section of the DESI focal plane, showing the one-of-a-kind robotic positioners. The optical fibers, which are installed in the robotic positioners, are backlit with blue light in this image. Credit: DESI collaboration

“The outstanding capability of DESI to collect spectra is also thanks to the instrument software,” said Santiago Serrano, an engineer at Institute of Space Sciences (ICE, CSIC) and IEEC, who has developed part of the algorithms needed to guide the telescope. He recognizes the invaluable effort of scores of scientists in Spain and around the world which have made the instrument and the experiment possible.

Spectra collected by DESI are the components of light corresponding to the colors of the rainbow. Their characteristics, including wavelength, reveal information such as the chemical composition of objects being observed as well as information about their relative distance and velocity.

As the universe expands, galaxies move away from each other, and their light is shifted to longer, redder wavelengths. The more distant the galaxy, the greater its “redshift.” By measuring galaxy redshifts, DESI researchers will create a 3D map of the universe. The detailed distribution of galaxies in the map is expected to yield new insights on the influence and nature of dark energy.

“Unraveling the properties of the mysterious Dark Energy is the main goal of DESI” said Licia Verde , ICREA professor at ICCUB. “We know that at present 70% of the energy content of the Universe is made of Dark Energy, but we know very little about its properties”.

Dark Energy determines the expansion rate of the universe , Verde explains. As the DESI instrument looks out in space and time, she says, “we can simultaneously observe the universe at different epochs, and by comparing them, figure out how the energy content evolves as the universe gets older.”

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 Technologies 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 Science and Technology of Mexico, the Ministry of Economy of Spain, and by the DESI member institutions.

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

Europe supports quantum science through the program Quantum Technologies Flagship, created to bring transforming advances to science, industry and society, and launch a solid industrial base based on the European tradition of excellence in quantum research. In this context, the 2021/2022 academic year launches the new master’s degree on Quantum Science and Technology.

Coordinated by the University of Barcelona, this master’s degree is the second one in Spain and the first one in Catalonia to major in this field. Among the participants are the Autonomous University of Barcelona, the Technical University of Catalonia, the Institute of Photonic Sciences (ICFO), the Barcelona Supercomputing Centre (BSC-CNS), the Institute of High Energy Physics (IFAE) and the Catalan Institute of Nanoscience and Nanotechnology (ICN2). The program, to be taught in English, is aimed at graduated students in Physics, Physics Engineering or related degrees, who want to continue their studies in this field. It will provide advanced knowledge to develop cutting-edge research on quantum science, from the theoretical side and the experimental branch in simulation, computing, sensors and communications.

On the one hand, communications and quantum sensors are part of the current economy, with products and services offered by specialized companies, which open new applications and new markets. On the other hand, computing and quantum simulation are under a research phase, but there are technological companies that are working on the first quantum computers for commercial uses that combine quantum computing and traditional ones. “Quantum physics will play an important role in the development of the near future, in our ability to estimate, communicate and measure in detail. For this reason, having a solid training in quantum sciences will be essential for promoting the limits of our knowledge and to develop new industrial products to benefit from the quantum properties”, notes Bruno Julià, lecturer at the Department of Quantum Physics and Astrophysics of the UB and coordinator of the master. “This master is the seed of a professional future in the field of quantum science”, adds the expert.

Apart from direct links to the industry through the QuantumCAT community, the new studies have the grouping of quantum technologies in Catalonia, which aim to promote synergies between different research centres and universities to strengthen the position of Catalonia as a distinguished region in quantum technologies. This link has enabled the participation of technological companies in the teaching program, as well as the promotion of the annual symposium of professional careers to facilitate the future integration of the students in the academic and the industrial sectors.

The fundamental objectives of the master’s degree are “on the one hand, to provide a solid education in theoretical physics and quantum information theory, and on the other, to offer a wide range of optional subjects to create a forward-looking study syllabus”, notes Julià, also member of the Institute of Cosmos Sciences of the UB.

The pre-enrolment period for the master’s degree is open until June 26. It also offers several grants. The course will start in September 2021 at the Faculty of Physics of the UB and will last a year (60 ECTS)..

Further information

From today on, the exhibition “Mars. The red mirror” can be seen in the room 2 in the Barcelona Center for Contemporary Culture (CCCB). The exhibition, which counted on the advice of researchers from the Institute of Cosmos Sciences of the UB (ICCUB-IEEC) and the contribution from the CRAI collection pieces.

This journey explores how we are linked to the red planet, from ancient times to date, through several approaches and disciplines. Science, arts and literature interact in a great exhibition project that explores our condition and future as a species. The exhibition coincides in time with three space missions –the first of them being NASA’s perseverance, whose probe arrived last February 18– that will promote knowledge on Mars and will open the window to new missions. The exhibition is structured into three big fields: Mars in ancient cosmos, Science and fiction in the red planet, and Mars in the Anthropocene. There are more than four hundred objects in the exhibition, among incunabula, sculptures, drawings, photographs, comics and even a Martian meteorite.

The Institute of Cosmos Sciences has collaborated in the definition of the exhibition since the beginning, through its director, Xavier Luri. As part of the exhibition, the activity Cosmos will take place on March 6: a conversation between Xavier Luri and ICCUB researcher Carme Jordi. There will be, in collaboration with CCCB, a session on the exploration of the space, with the participation of several UB institutes. The meeting will treat this topic from different perspectives, such as the economic and the technological ones. Carme Jordi will also take part in the ALIA Mission, an educational project by the CCCB for upper secondary education students. Its objective is to relate scientific dissemination to literary creation.

More information:

• IEEC's press release
• UB's press release

• Dr. Ferré-Mateu is one of the hundred researchers selected from around the world

• Homeward Bound project is a transformational leadership initiative for women with a background in STEMM from around the world

• The program will conclude with a three-week on-board ship voyaging to Antarctica

Dr. Ferré-Mateu, researcher at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), will be part of the sixth program along with a hundred researchers. The 12-month program comprises lectures, personal and leadership development tools, coaching sessions, visibility, training and the opportunity to develop meaningful collaborations – in forums, in teams with a focus on areas of interest, and in small diverse cohorts ending with a three-week on-board ship voyaging to Antarctica.

‘For me this journey to Antarctica represents the challenges we face as individuals and as a society.', commented Dr. Ferré-Mateu. ' Before we can think about reaching new worlds, we need to start taking care of our own, and I hope that the tools learnt during this journey will have an impact on the way we do science. It is one of the greatest adventures ever and I’m just thrilled to be part of it!’, she added.

What is the Homeward Bound project?

The Homeward Bound project was created in Australia in 2016. This project aims to build a global collaboration of 1000 women with backgrounds in STEMM for over ten years so they have the opportunity to take up leadership roles globally and to proactively contribute to a sustainable world, both individually and collectively. They will be visible, collaborative, networked and impacting the decisions made in many quarters for the greater good.

Who is Dr. Ferré Mateu?

Dr. Ferré Mateu’s research has been focused on the study of the cosmic evolution of galaxies of different types. They are a crucial building block to constrain the current galaxy formation and evolution paradigm. Moreover, to some degree, they are also a crucial piece of understanding a bit better the most fundamental question of human beings: where do we come from?

For this, she has been studying the fossil record of the stars in galaxies, to understand how they were and how they have evolved over cosmic time, in a similar way an archaeologist would reveal how the ancient populations lived by examining their remains. This quest has taken her to live, literally, all around the globe: the Canaries, Hawaii and Australia. This has allowed her to carry her science in forefront facilities while enjoying the wonders of such places by doing her favourite hobbies such as surfing, diving, hiking and traveling. Since 2018, Dr. Ferré-Mateu holds a Postdoctoral Junior Leader Fellowship at our institute, where she is one of the members of the Galaxy Structure and Evolution research group.

Her contribution to disseminating science to younger generations and advocating for women equity has become a very important part of her work participating in chats and events like Chatea con una Astrónoma motivating young girls into pursuing STEM careers or being part of "Journey through the Universe" that brings astronomy to the classrooms in Hilo, Hawaii.

You can follow her journey to Antarctica on Twitter or Instagram on the hashtag #AnnetainAntarctica.hb6 and her Instagram account @annetainantarctica.hb6

Links:

Dr. Ferré Mateu’s website

Homeward Bound project

Institute of Cosmos Sciences

Outreach events

Contacts:

ICCUB Communication Office

Barcelona, Spain

Esther Pallares

E-mail: secretariacientifica@icc.ub.edu

Dr. Anna Ferré Mateu

Barcelona, Spain

Institute of Cosmos Sciences

E-mail: aferremateu@icc.ub.edu

The Institute of Cosmos Sciences of the Universitat de Barcelona will use the December 2020 Early Data Release 3 (EDR3) of the European Space Agency mission Gaia to investigate Milky Way star formation and its interaction with its satellite galaxies, employing OCRE’s cloud resources for data mining, N-body simulations, and Bayesian techniques on the Gaia catalogue containing 1.8 billion sources.

Fifteen innovative research projects will benefit from commercial cloud solutions through EU cloud project Open Clouds for Research Environments (OCRE), demonstrating the effectiveness of cloud services in research.

€1.175 million will be distributed to the successful applicants, each receiving between €50,000 and €100,000. In its first call for the adoption of the cloud services available through the OCRE IaaS+ framework agreements, OCRE received 31 applications. All applications were screened by the OCRE cloud adoption funding team and overseen by the OCRE External Advisory Board.

The distribution of cloud adoption funding is a key milestone in OCRE’s goal of piloting a digital single market for cloud and digital services for European research. The research projects will be able to benefit from 27 different commercial cloud-based platforms that were sourced through the OCRE IaaS+ Tender concluded mid-2020 and will be made available in the OCRE Service Catalogue in the first quarter of2021.

Through this single procurement, thousands of research institutions across the European Research Area will be able to benefit from easy and procurement regulation-compliant access to commercial cloud services.

OCRE Adoption Funding Lead Jan Meijer (Uninett)said, “thanks to the good response to the call for projects we managed to assemble a balanced portfolio of 15 projects; showcasing the benefits of commercial cloud services on research outcomes from different angles. Our hope is that these showcases will inspire other researchers to follow in their footsteps and leverage the benefits of the OCRE portfolio of services for their research.”

More information about Gaia here.

• The new data allow us to determine that the ancient disc had a smaller extent compared to the Milky Way’s current disc size.

• Gaia provides the first measurement of the curvature of the Solar System’s orbit around the galaxy in the history of optical astronomy.

• The Gaia Catalogue of Nearby Stars has been released containing around 92 percent of the stars within 100 parsecs (326 light years) of the Sun.

The motion of stars in the outskirts of our galaxy hints at significant changes in the history of the Milky Way. This and other equally fascinating results come from a set of papers that demonstrate the quality of ESA’s Gaia Early third Data Release (EDR3), which is made public today.

Astronomers from the Gaia Data Processing and Analysis Consortium (DPAC) saw the evidence of the Milky Way’s past by looking at stars in the direction of the Galaxy’s ‘anticentre’. This is in the exact opposite direction on the sky from the centre of the galaxy.

The results on the anticentre come from one of the four ‘demonstration papers’ released alongside the Gaia data. The others use Gaia data to provide a huge extension to the census of nearby stars, derive the shape of the Solar System’s orbit around the centre of the Galaxy, and probe structures in two nearby galaxies to the Milky Way. The papers are designed to highlight the improvements and quality of the newly published data.

Join the events organized to celebrate the early gaia data release 3

To the galactic anticentre

The new Gaia data have allowed astronomers to trace the various populations of older and younger stars out towards the very edge of our galaxy – the galactic anticentre. Computer models predicted that the disc of the Milky Way will grow larger with time as new stars are born. The new data allow us to see the relics of the 10 billion-year-old ancient disc and so determine its smaller extent compared to the Milky Way’s current disc size.

The new data from these outer regions also strengthen the evidence for another major event in the more recent past of the galaxy.

The data show that in the outer regions of the disc there is a component of slow-moving stars above the plane of our galaxy that are heading downwards towards the plane, and a component of fast-moving stars below the plane that are moving upwards. This extraordinary pattern had not been anticipated before. It could be the result of the near-collision between the Milky Way and the Sagittarius dwarf galaxy that took place in our galaxy’s more recent past.

The Sagittarius dwarf galaxy contains a few tens of millions of stars and is currently in the process of being cannibalised by the Milky Way. Its last close pass to our galaxy was not a direct hit, but this would have been enough so that its gravity perturbed some stars in our galaxy like a stone dropping into water.

Using Gaia DR2, members of DPAC had already found a subtle ripple in the movement of millions of stars that suggested the effects of the encounter with Sagittarius sometime between 300 and 900 million years ago. Now, using Gaia EDR3, they have uncovered more evidence that points to its strong effects on our galaxy’s disc of stars.

“The patterns of movement in the disc stars are different to what we used to believe,” says Teresa Antoja, researcher at the Institute of Cosmos Sciences of the University of Barcelona, who worked on this analysis with DPAC colleagues. Although the role of the Sagittarius dwarf galaxy is still debated in some quarters, Teresa says, “It could be a good candidate for all these disturbances, as some simulations from other authors show.”

Measuring the Solar System’s orbit

The history of the galaxy is not the only result from the Gaia EDR3 demonstration papers. DPAC members across Europe have performed other work to demonstrate the extreme fidelity of the data and the unique potential for unlimited scientific discovery.

In one paper, Gaia has allowed scientists to measure the acceleration of the Solar System with respect to the rest frame of the Universe. Using the observed motions of extremely distant galaxies, the velocity of the Solar System has been measured to change by 0.23 nm/s every second. Because of this tiny acceleration, the trajectory of the Solar System is deflected by the diameter of an atom every second, and in a year this adds up to around 115 km. The acceleration measured by Gaia shows a good agreement with the theoretical expectations and provides the first measurement of the curvature of the Solar System’s orbit around the galaxy in the history of optical astronomy.

A new stellar census

Gaia EDR3 has also allowed a new census of stars in the solar neighbourhood to be obtained. The Gaia Catalogue of Nearby Stars contains 331 312 objects, which is estimated to be 92 percent of the stars within 100 parsecs (326 light years) of the Sun. The previous census of the solar neighbourhood, called the Gliese Catalogue of Nearby stars, was carried out in 1957. It possessed just 915 objects initially, but was updated in 1991 to 3803 celestial objects. It was also limited to a distance of 82 light years: Gaia’s census reaches four times farther and contains 100 times more stars. It also provides location, motion, and brightness measurements that are orders of magnitude more precise than the old data.

Beyond the Milky Way

A fourth demonstration paper analysed the Magellanic Clouds: two galaxies that orbit the Milky Way. Having measured the movement of the Large Magellanic Cloud’s stars to greater precision than before, Gaia EDR3 clearly shows that the galaxy has a spiral structure. The data also resolve a stream of stars that is being pulled out of the Small Magellanic Cloud, and hints at previously unseen structures in the outskirts of both galaxies.

At 12:00 CET on 3 December, the data produced by the many scientists and engineers of the Gaia DPAC Consortium become public for anyone to look at and learn from. This is the first of a two-part release; the full Data Release 3 is planned for 2022.

“Gaia EDR3 is the result of a huge effort from everyone involved in the Gaia mission. It’s an extraordinarily rich data set, and I look forward to the many discoveries that astronomers from around the world will make with this resource,” says Timo Prusti, ESA’s Gaia Project Scientist. “And we’re not done yet; more great data will follow as Gaia continues to make measurements from orbit.”

Gaia Mission

The Gaia satellite, which was launched in December 2013, is destined to create the most accurate map of the Milky Way. By making accurate measurements of the positions and motions of stars in the Milky Way, it is answering questions about the origin and evolution of our home galaxy.

Gaia EDR3 contains detailed information on more than 1.8 billion sources, detected by the Gaia spacecraft. This represents an increase of more than 100 million sources over the previous data release (Gaia DR2), which was made public in April 2018. Gaia EDR3 also contains colour information for around 1.5 billion sources, an increase of about 200 million sources over Gaia DR2. As well as including more sources, the general accuracy and precision of the measurements has also improved.

Participation of the Barcelona team

The ICCUB team (UB-IEEC), led by Professor Carme Jordi and professors Xavier Luri and Francesca Figueras, from the Department of Quantum Physics and Astrophysics, has participated in the Gaia mission from the beginning. Their role was focused on the scientific and technological design of the project, the development of the data processing system and the production of simulated data.

Regarding the now presented data, the Barcelona team coordinates the group that has developed the archive of the mission. It is also responsible for running several key processes for processing the data that arrives daily from the satellite, the first step in obtaining results for scientific use such as those now published. The group is also responsible for the process of pairing the various observations of the same star, and it collaborates in the calibration of star photometry and is fully involved in the scientific exploitation of the data. Finally, the Catalan researchers have played an important role in the performance verification papers, articles that are published together with the data and which verify their quality. Specifically, they have led four of these articles and have played a significant part in much of the rest.

The ICCUB Gaia team (UB-IEEC), made up of about thirty scientists and engineers, was awarded the 2013 City of Barcelona Award for Experimental Sciences and Technology. It is part of the Gaia Data Processing and Analysis Consortium, made up of more than 400 people from around twenty European countries, and leads the creation of the archive of the mission. Some of its members are part of the Gaia Science Team (GST), the ESA scientific advisory body.

More information:

• Gaia's webpage
• ICCUB's Gaia Team webpage
• Gaia ICCUB team detects a shake in the Milky Way
• Memory game
• Coloquio-tertulia sobre los datos de gaia - EDR3
• Gaia, la Galaxia en tus manos
• Institute of Cosmos Sciences (ICCUB)
• Teresa Antoja's webpage

Verification papers:
Gaia Early Data Release 3: The Gaia catalogue of nearby stars Gaia Collaboration, Smart, R.L., et al.
Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds Gaia Collaboration, Luri, X., et al.
Gaia Early Data Release 3: The Galactic anticentre Gaia Collaboration, Antoja, T., et al.
Gaia Early Data Release 3: Acceleration of the solar system from Gaia astrometry Gaia Collaboration, Klioner, S.A., et al.

This Thursday, December 3, at 12 noon, the European Space Agency (ESA) will make a new data release from the Gaia mission with more than 1.8 billion observed objects. This is one of the great milestones expected by the astronomical community worldwide.

The different teams that make up the Gaia project will organize scientific seminars to explain the first obtained results and the lessons learned with the Gaia data, as well as a breakthrough in science that is beginning to appear. Data Processing and Analysis Consortium team (DPAC), which brings together more than 400 experts, is organizing an online meeting aimed at the scientific community, which will be coordinated by members of the Institute of Cosmos Sciences of the University of Barcelona (ICCUB).

Getting to know Gaia better: disseminative conference and memory game

On the same day, December 3, at 7 p.m., there will be an informative conference aimed at the general public, given by ICCUB researchers Josep Manel Carrasco and Mercè Romero. In the conference, they will explain how astronomy is revolutionizing the Gaia satellite, which provides unpublished clues about the origin and evolution of our galaxy, the Milky Way. They will describe the mission and explain Gaia’s strategy to observe the Universe by analysing the latest discoveries.

Also, the ICCUB team has created a Gaia memory game, which can be downloaded and printed, or played online. The twenty images in the game correspond to the space mission and are accompanied by descriptive texts.

Participation of the Barcelona team

TheICCUB team(UB-IEEC), led by Professor Carme Jordi and professors Xavier Luri and Francesca Figueras, from the Department of Quantum Physics and Astrophysics, has participated in the Gaia mission from the beginning. Their role was focused on the scientific and technological design of the project, the development of the data processing system and the production of simulated data.

Regarding the now presented data, the Barcelona team coordinates the group that has developed the archive of the mission. It is also responsible for running several key processes for processing the data that arrives daily from the satellite, the first step in obtaining results for scientific use such as those now published. The group is also responsible for the process of pairing the various observations of the same star, and it collaborates in the calibration of star photometry and is fully involved in the scientific exploitation of the data. Finally, the Catalan researchers have played an important role in the performance verification papers, articles that are published together with the data and which verify their quality. Specifically, they have led four of these articles and have played a significant part in much of the rest.

The ICCUB Gaia team (UB-IEEC), made up of about thirty scientists and engineers, was awarded the 2013 City of Barcelona Award for Experimental Sciences and Technology. It is part of the Gaia Data Processing and Analysis Consortium, made up of more than 400 people from around twenty European countries, and leads the creation of the archive of the mission. Some of its members are part of the Gaia Science Team (GST), the ESA scientific advisory body.

Quick flashes of light in the night sky have been linked to the growing mass of satellites and debris zipping around Earth’s orbit.

The orbital flashes, often mistaken for stars, occur 1,000 times an hour, according to new research led by the University of North Carolina at Chapel Hill that may improve the accuracy of astronomical data.

Stargazers have long been tantalized by the inexplicable glimmers and the study published Nov. 5 in The Astrophysical Journal Letters provides a potential explanation for those mysterious flashes.

Most of the flashes require powerful telescopes for viewing, but up to 100 of them are bright enough to see with the naked eye in a suburban community.

“Astronomical surveys have seen occasional reflected light glints from satellites; those flashes can cause false alarms in surveys looking for new events in the sky,” said lead study author Hank Corbett, graduate student at the UNC-Chapel Hill Department of Physics and Astronomy.

“For the first time, we have studied the flashes in a systematic way that will help reduce their impact on astronomical discoveries.”

The team at UNC-Chapel Hill, along with collaborators from San Diego State University and the University of Barcelona, reported more than 100,000 flashes over a six-month period.

The flashes were observed with the Evryscopes, telescopes in California and Chile constructed and funded by the National Science Foundation. The pair of robotic, gigapixel-camera telescopes observe the entire sky above their observatories every two minutes.

“These measurements allow us to predict the impact of reflected-light flashes on both current and future professional observatories and develop techniques to mitigate their effects on data,” Corbett said.

The orbital flashes are reflected not only from the satellites relied on for navigation, communication, weather forecasting, and more, but also from space trash such as dead satellites, paint chips and errant nuts and bolts that has accumulated since space exploration began six decades ago.

These short duration flashes can be indistinguishable from stars in images from professional observatories and are typically visible for only a fraction of a second.

“Millions of stargazers have likely observed these quick glimmers of light in the night sky,” Corbett said. “Reflected-light flashes happen so fast that observers may dismiss them as visual noise, but this research provides a potential explanation for those mysterious flashes.

Rogue reflections from Earth satellites take two forms: short duration flashes that can lead to mistaken astrophysical events and streaks associated with fast-moving or slowly rotating satellites like SpaceX Starlink.

Companies are competing to launch thousands of satellites capable of beaming internet coverage to Earth. However, in the new study, researchers conclude that the upcoming satellite internet constellations, like SpaceX Starlink, are unlikely to contribute significantly to the appearance of flashes, though there are other potential impacts of satellite constellations on astronomers.

Bright streaks caused by sun-illuminated satellites moving across an image are a separate class of events that needs to be studied.

Additional authors include Nicholas Law, Alan Vasquez, Ward S. Howard, Amy Glazier, Ramses Gonzalez, Jeffrey Ratzloff and Nathan Galliher, all of UNC-Chapel Hill, Octavi Fors of UNC-Chapel Hill and University of Barcelona and Robert Quimby of San Diego State University and University of Tokyo.

The classification and definitive analysis of the 39 events detected by Virgo and LIGO in the third observation period (which ran from April to October 2019) was published today on the ArXiv online archive. Most of these are black hole mergers, the characteristics of which, however, question some established astrophysical models and open up new scenarios. A likely merger of neutron stars and two probable 'mixed' neutron star-black hole systems were also detected in the same period.

It took a year of work and complex analysis by the researchers of the Virgo and LIGO scientific collaborations to complete the study of all of the gravitational-wave signals that were recorded by the Virgo interferometer, installed at the European Gravitational Observatory, in Italy, and the two LIGO detectors, in the US, during the data-taking period - called 'O3a' - which ran from the 1st of April to the 1st of October, 2019. Events included: 36 mergers of black holes; a likely merger of a binary system of neutron stars; and two systems that were most likely composed of a black hole and a neutron star. Among these, four "exceptional events" have, during the last year, already been published, but the catalogue released today provides, for the first time, a complete picture of the extraordinarily large number of recorded gravitational-wave signals and their sources. It represents a wealth of observations and data on the physics of black holes, barely imaginable until only a few years ago.

"Since the end of the O2 observing run in August 2017, many efforts have been made to upgrade many of the technical components and different sectors of the detector, in order to boost the Virgo sensitivity across the whole frequency range", said Ilaria Nardecchia, a researcher at the University of Roma Tor Vergata and member of the Virgo Collaboration. "We reaped the benefits of our work because we doubled the sensitivity of the detector!"

Indeed, between September 2017, and April 2019, the sensitivity of the three detectors has been significantly improved. This has led, for example, to Virgo becoming capable of observing a volume of the universe almost ten times larger than in the previous observational run (O2).

"Observations with Advanced Virgo and LIGO have exceeded expectations. As well as opening a new and exciting phase in the history of human observation of the cosmos, we are seeing events that either lacked observational evidence until now, or go beyond our current understanding of stellar evolution", said Ed Porter, directeur de recherche CNRS at APC-Paris, and member of the Virgo Collaboration. "Just five years after the first detection of gravitational waves, we can say that gravitational astronomy is a concrete reality."

The detection of gravitational signals allows us, in fact, for the first time, to closely observe the dynamics of extraordinary mergers of black holes and neutron stars, which release bursts of energy equivalent to several solar masses in gravitational waves. This allows us to study, as never before, the physics of black holes, the cosmic phenomena that generate them and even the characteristics of the largest populations of black holes. Actually, the results of the present catalogue raise serious questions about the validity of some of the astrophysical scenarios and models, which until now seemed the most plausible.

In particular, the masses of black holes, presented in the O3a catalogue, question various theoretical and observational limits on the mass ranges of black hole populations. Some observations, for example, indicate the presence of compact objects (which could be either black holes or neutron stars) exactly in the gap between the mass of the heaviest neutron stars and that of the lightest black holes observed by astronomers to date. This gap could therefore narrow or even disappear. Other observed black holes have a mass with a value between 65 and 120 solar masses; a range forbidden by stellar evolution models. According to these models, the very massive stars, beyond a certain threshold, are completely disrupted by the supernova explosion, due to a process called pair instability, and leave behind only gas and cosmic dust. The existence of black holes in the range prohibited by pair instability suggests other mechanisms of black hole formation, such as the merger of smaller black holes or the collision of massive stars, but may also indicate the need to revise our description of the final stages of the lives of stars.

The publication of the O3a catalogue is the conclusion of complex work involving many phases and covering detector calibration, data characterisation and data analysis. The catalogue for each observation run is only published once researchers have the final validated dataset, thus making it possible to estimate the physical parameters (such as distance, mass and spins) of the black-hole and neutron-star mergers, as well as a confident estimate of their margins of error. Of the 39 events presented in this latest catalogue, 26 were announced immediately after detection, while 13 are reported for the first time in the paper published today. These add to the 11 gravitational-wave events reported by LIGO and Virgo for the previous runs (O1 and O2). In addition to the LIGO-Virgo events catalogue, three other articles have also been released today on the arXiv server: the global analysis of the astrophysical properties of the gravitational-waves sources; new tests of the theory of general relativity; and the search for gravitational-wave signals coincident with gamma-ray bursts."

"These papers are very important and represent a further step forward in a long and exciting journey", said Giovanni Losurdo, INFN researcher and spokesperson for the Virgo Collaboration. "We are already looking forward to the results of the second part of the third observation period (O3b). The very high number of events still to analyse and understand promises that the next catalogue will be as exciting, if not more so, than this one. Meanwhile, we are striving to implement a substantial upgrade of the Virgo detector, aiming to pursue the next run, in 2022, again with a considerably improved sensitivity."

Citizen-science projects for gravitational-wave data-analysis

Two citizen-science projects, Gravity Spy for LIGO and the European project, REINFORCE for Virgo, allow everyone to contribute to the identification of spurious signals and therefore to the discovery of new gravitational-waves signals, by collaborating directly with researchers involved in the analysis of the data of the three interferometers.

In fact, although external as well as internal noise sources are minimised, the data taken by the interferometers are still plagued by some disturbances. In some cases, these are monitored by witness sensors and are then subtracted from the data in real-time. Nevertheless, the identification of other noises is more problematic and requires off-line dedicated analysis in order to flag them. This is the case with glitchy noises; those that are generated, for instance, by light scattered off the main laser beam and that then recombine with it. The careful studies required to claim a true gravitational-wave signal explain why the LIGO and Virgo Collaborations issue alerts of a candidate event to the scientific community soon after it has been measured. This can then either be confirmed by subsequent analysis and hence considered a true signal or not. Thanks to Gravity Spy and REINFORCE, citizen scientists can help researchers in this complex analysis work by directly accessing the data detected by the LIGO and Virgo interferometers.

Link to papers:

• Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
• Population properties of compact objects from the second LIGO–Virgo Gravitational-Wave Transient Catalog
• Tests of General Relativity with Binary Black Holes from the second LIGO–Virgo Gravitational-Wave Transient Catalog
• Search for Gravitational Waves Associated with Gamma-Ray Bursts detected by Fermi and Swift during the LIGO-Virgo Run O3a

Image caption: The image shows sky localisations for the different LIGO-Virgo detections that are included in the O3a catalogue. Each localisation - represented by shaded areas on the map - is deduced on the basis of information provided by the three detectors in the network. The day and time of arrival on Earth, a scientific name and the time it took the signal to reach the Earth from wherever in the Universe it was generated, are all recorded. The smaller the shaded area in the sky map, the better the signal has been localised. Localisation is crucial in enabling follow-up searches with different messengers, such as light or neutrinos.

• The announcement is made in light of the recent approval of the preliminary draft of the Spanish government’s budget which announces an investment of more than five billion euros in science
• The signatories demand a national pact that includes long-term strategies aimed at promoting frontier science and business innovation
• The document aims to add and provide strategic solutions to the recent Pact for Science and Innovation that the Government has just announced

SOMMa, ASEICA and AseBio, entities that together account for almost ten thousand researchers across the public and private sector, dozens of research centres and nearly 300 leading Spanish companies in the biotechnology sector, join their voices to urge the political class to transform the country. More than 40 organisations supporting stronger support for science and innovation have signed a document that calls for Spain to reach and exceed 2.5% investment in R&D by 2027 and radically change its current economic model.

The signatories consider this is a crucial moment of putting R&D at the centre of Spain’s future strategy for a sustainable and resilient recovery. It is a unique window of opportunity presented by yesterday’s preliminary draft of the state’s new general budget, the European Reconstruction Plan, the "Green Deal" and the missions of the new Horizon Europe Framework Program of the European Union.

Furthermore, the public has been able to grasp the need to have a solid research capacity for the challenges we are currently facing. Despite this, Spain invests just 1.24% of its GDP in R&D, a figure much lower than the EU average (2.12%), and far from countries such as Germany, Denmark or Austria (around 3%).

The call for action proposes a broad range of administrative and legal recommendations, as well as the implementation of strategic actions so that science and innovation act as the engines for the recovery of the country. The transformation of the economic model would counterbalance the dependence of sectors heavily affected by the current pandemic, giving Spain new opportunities and a stronger position for the future. Crystallizing the great Spanish potential in R&D would lay the foundations for a solid recovery through a sustainable, competitive economic model based on providing high added value.

“The current context has abruptly exposed the shortcomings of our economic model. Spain is thought to be one of the advanced economies most affected by the pandemic, making it essential to change the foundations of our economic model before we can regrow. This is a turning point which we cannot back away from, as it is only through a new economic model that we can ensure the future of Spain. Taking urgent action through the state’s general budget is just the starting point. A state pact for R&D is necessary now more than ever." Luis Serrano, president of SOMMa and director of the Centre for Genomic Regulation.

“Covid-19 has revealed what we have been warning for a long time: the urgent need to invest in science and innovation to ensure the health of our citizens and to develop an economy based on knowledge, not entertainment. We must take the bull by the horns: we need stable long-term plans and short-term solutions to meet these challenges. Let's say it once again: research is not a luxury, it is the only way we have to ensure the health and quality of life of our fellow citizens. And this does not depend on ideologies, it is a project that cuts across all divides”. Xosé Bustelo, President of ASEICA.

“This appeal to our political representatives, to the administration and to society itself, is nothing but a joint demand for a long-term strategy that promotes science and innovation in our country and places them at the heart of its strategy. Innovative companies and entities are committed to this effort if we have an adequate and stable framework that allows us to work collaboratively with the rest of the agents of the R & D & I ecosystem and thus contribute to the transformation of our production model. " Ion Arocena, CEO of AseBio.

The appeal led by SOMMa, ASEICA and AseBio centres around three groups of measures, the first of which focuses on the strengthening of basic and translational frontier science. The signatories demand a simplification of expense management and associated bureaucracy, an increase and optimization of investment, new talent recruitment programs, and mechanisms that favour the stability of research projects promoted by public organizations.

The second tier of recommendations propose measures that strengthen innovation and promote the transition to a sustainable economy with high added value. It is proposed to promote public-private cooperation and innovative business fabric, as well as the creation of a patronage-fundraising law. It also calls for a need to undertake a profound reform of the aid model for business R&D and a legal framework that minimizes uncertainties and provides stability and security to the R&D system.

Finally, the third tier of recommendations calls for new mechanisms to increase synergies between the academic and business sectors. Key to this will be the development of a long-term national strategy that includes the autonomous communities, increasing the capacity to transfer the knowledge of universities and research institutes into innovative solutions and the creation of new technology-based companies. Finally, the signatories appeal to cultivate the value of science as a reference for citizenship, the business community and political action.

You can find the full document with the list of signatories here (in Spanish).