A group of scientists led by Stefano Torniamenti (University of Padova) and in close collaboration with Mark Gieles (ICREA, ICCUB-IEEC), Friedrich Anders (ICCUB-IEEC), have published new results that hint at the existence of several black holes in the Hyades cluster, making them the closest black holes to Earth ever detected. The work was carried out during a research stay of Dr. Torniamenti at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), one of the research units conforming the Institute of Space Studies of Catalonia (IEEC) and it appeared in the Monthly Notices of the Royal Astronomical Society this September.

Since their discovery, black holes have been one of the most mysterious and fascinating phenomena in our Universe, becoming an object of study for researchers all over the world.  This is particularly true for small black holes, because they have been the most observed  during the detection of gravitational waves. Since the detection of the first gravitational waves in 2015, the detectors have observed many events which correspond to mergers of pairs of lower-mass black holes.  

In the newly published paper, the team of astrophysicists use simulations that follow the motion and evolution of all the stars of the Hyades, which is the closest open cluster to our Solar System (its distance to the Sun is approximately 45 parsecs or 150 light years) to reproduce its current state. Open clusters are loosely bound groups of hundreds of stars that share some properties such as their age and chemical characteristics. The results of the simulation were then compared to the actual position and velocities of the Hyades stars, which are now accurately known thanks to the observations made by the Gaia Satellite of the European Space Agency (ESA).

“Our simulations can only simultaneously match the mass and size of the Hyades if some black holes are present at the cluster centre at the present day (or until recently)” says Stefano Torniamenti, now postdoctoral researcher at the University of Padova and first author of the paper. The work was done during a research stay of Dr. Torniamenti at the ICCUB and it is the result of the close collaboration of the University of Padova, the Institute of Cosmos Sciences of the University of Barcelona (ICCUB-IEEC), the University of Cambridge (UK), the European Southern Observatory (ESO) and Sun Yat-sen University (China).

The Hyades observed properties are best reproduced by simulations with 2 or 3 black holes at the present day although the simulations where all the black holes were recently ejected (less than 150 million years ago, roughly the last quarter of the age of the cluster) can still give a good match because the cluster’s evolution could not erase the imprints of its previous black hole population.

The new results indicate that the black holes born in the Hyades are still inside the cluster, or very near the cluster, which makes them the closest black holes to the Sun, much closer than the prior candidate, the black hole Gaia BH1, which is at 480 parsecs from the Sun.

In the last few years, the advent of the ESA Gaia space telescope has allowed us, for the first time, to study in detail the position and velocity of the stars of open clusters, and to identify each star with confidence.

“This observation helps us to understand how the presence of black holes affects the evolution of star clusters and how in turn star clusters contribute to the gravitational wave sources ”, comments Prof Mark Gieles, host of the first author in Barcelona. “These results also give us a glimpse at how these mysterious objects are distributed throughout the galaxy.”

Paper details

“Stellar-mass black holes in the Hyades star cluster?”

DOI: 10.1093/mnras/stad1925

Contact information

Stefano Torniamenti

University of Padova, Italy

Email: s.torniamenti@gmail.com

Mark Gieles

ICREA, Institute of Cosmos Sciences of the University of Barcelona (ICCUB), Institute of Space Studies of Catalonia (IEEC)

Barcelona, Spain

Email: mgieles@icc.ub.edu

New images from the James Webb Space Telescope have revealed, for the first time, starlight from two massive galaxies hosting actively growing black holes – quasars – seen less than a billion years after the Big Bang. A new study in Nature this week finds the black holes have masses close to a billion times that of the Sun, and the host galaxy masses are almost one hundred times larger, a ratio similar to what is found in the more recent universe. A powerful combination of the Subaru Telescope and the JWST has paved a new path to study the distant universe.   

The existence of such massive black holes in the distant universe has created more questions than answers for astrophysicists. How could these black holes grow to be so large when the universe was so young? Even more puzzling, observations in the local universe show a clear relation between the mass of supermassive black holes and the much larger galaxies in which they reside. The galaxies and the black holes have completely different sizes, so which came first: the black holes or the galaxies?  This is a “chicken-or-egg” problem on a cosmic scale.

An international team of researchers, led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Researcher Xuheng Ding and Professor John Silverman, and Peking University Kavli Institute for Astronomy and Astrophysics (PKU-KIAA) Kavli Astrophysics Fellow Masafusa Onoue have started to answer this question with the James Webb Space Telescope (JWST), launched in December 2021. Studying the relation between host galaxies and black holes in the early universe allows scientists to watch their formation, and see how they are related to one another.  

"The central black hole acts on its hosting galaxy in some way to produce the observed relation. Understanding this mechanism is a hot topic and this paper will bring us closer to doing so", says Dr. Kazushi Iwasawa, researcher of the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC) and one of the core members of the team that discovered the early-universe quasars.

Quasars are luminous, while their host galaxies are faint, which has made it challenging for researchers to detect the dim light of the galaxy in the glare of the quasar, especially at great distances.  Before the JWST, the Hubble Space Telescope was able to detect host galaxies of luminous quasars when the universe was just under 3 billion years old, but no younger. 

The superb sensitivity and the ultra-sharp images of the JWST at infrared wavelengths finally allowed researchers to push these studies to the time when the quasars and galaxies first formed.  Just a few months after JWST started regular operations, the team observed two quasars, HSC J2236+0032 and HSC J2255+0251, at redshifts 6.40 and 6.34 when the universe was approximately 860 million years old. These two quasars were discovered in a deep survey program of the 8.2m-Subaru Telescope on the summit of Maunakea in Hawai’i.  The relatively low luminosities of these quasars made them prime targets for measurement of the host galaxy properties, and the successful detection of the hosts represents the earliest epoch to date at which starlight has been detected in a quasar.  

The images of the two quasars were taken at infrared wavelengths of 3.56 and 1.50 micron with JWST’s NIRCam instrument, and the host galaxies became apparent after carefully modeling and subtracting glare from the accreting black holes. The stellar signature of the host galaxy was also seen in a spectrum taken by JWST’s NIRSPEC for J2236+0032, further supporting the detection of the host galaxy.

Analyses of the host galaxy photometry found that these two quasar host galaxies are massive, measuring 130 and 34 billion times the mass of the Sun, respectively. Measuring the speed of the turbulent gas in the vicinity of the quasars from the NIRSPEC spectra suggest that the black holes that power them are also massive, measuring 1.4 and 0.2 billion times the mass of the Sun. The ratio of the black hole mass to host galaxy mass is similar to those of galaxies in the more recent past, suggesting that the relationship between black holes and their hosts was already in place 860 million years after the Big Bang.  

Ding, Silverman, Onoue and their colleagues will continue this study with a larger sample using scheduled Cycle 1 JWST observations, which will then further constrain models for the coevolution of black holes and their host galaxies. The team recently learned that they have been awarded additional time for JWST in its next cycle to study the host galaxy of J2236+0032 in much more detail.  

Details of this study were published in Nature on June 28.

Paper details
“Detection of stellar light from quasar host galaxies at redshifts above 6”
DOI: 10.1038/s41586-023-06345-5

Related links

Astronomers Discover 83 Supermassive Black Holes in the Early Universe (Subaru Telescope press release on March 13, 2019)

https://subarutelescope.org/en/results/2019/03/13/2731.html 

Expressing the distance to remote objects

https://www.nao.ac.jp/en/astro/glossary/expressing-distance.html

About the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP)

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey, using the Hyper Suprime-Cam on the 8.2m Subaru Telescope on the summit of Maunakea in Hawai’i, aimed at addressing some of the most important and outstanding questions in astronomy today, including the nature of dark matter and dark energy. 

The survey consisted of 330 nights of observation time on the Subaru Telescope between 2014 and 2021, mapping out an area of more than 1100 square degrees, or 5,500 times the area of the Moon, of the deep universe. 

The HSC-SSP is led by the astronomical communities of Japan and Taiwan, and Princeton University.

The BlackGEM array, consisting of three new telescopes located at ESO’s La Silla Observatory, has begun operations. The telescopes will scan the southern sky to hunt down the cosmic events that produce gravitational waves, such as the mergers of neutron stars and black holes.

Some cataclysmic events in the Universe, such as the collision of black holes or neutron stars, create gravitational waves, ripples in the structure of time and space. Observatories like the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer are designed to detect these ripples. But they cannot pinpoint their origin very accurately nor see the fleeting light that results from the collisions between neutron stars and black holes. BlackGEM is dedicated to quickly scanning large areas of the sky to precisely hunt down gravitational-wave sources using visible light.

“With BlackGEM we aim to scale up the study of cosmic events with both gravitational waves and visible light,” says Paul Groot of Radboud University in the Netherlands, the project’s Principal Investigator. “The combination of the two tells us much more about these events than just one or the other.”

By detecting both gravitational waves and their visible counterparts, astronomers can confirm the nature of gravitational-wave sources and determine their precise locations. Using visible light also allows for detailed observations of the processes that occur in these mergers, such as the formation of heavy elements like gold and platinum.

To date, however, only one visible counterpart to a gravitational-wave source has ever been detected. Furthermore, even the most advanced gravitational-wave detectors such as LIGO or Virgo cannot precisely identify their sources; at best, they can narrow the location of a source down to an area of approximately 400 full moons in the sky. BlackGEM will efficiently scan such large regions at high enough resolution to consistently locate gravitational-wave sources using visible light.

BlackGEM’s three constituent telescopes were built by a consortium of universities: Radboud University, the Netherlands Research School for Astronomy, and KU Leuven in Belgium. The telescopes are each 65 centimetres in diameter and can investigate different areas of the sky simultaneously; the collaboration eventually aims to expand the array to 15 telescopes, improving its scanning coverage even more. BlackGEM is hosted at ESO’s La Silla Observatory in Chile, making it the first array of its kind in the southern hemisphere.  

“Despite the modest 65-centimetre primary mirror, we go as deep as some projects with much bigger mirrors, because we take full advantage of the excellent observing conditions at La Silla,” says Groot.

Once BlackGEM precisely identifies a source of gravitational waves, larger telescopes such as ESO’s Very Large Telescope or the future ESO Extremely Large Telescope can carry out detailed follow-up observations, which will help to shed light on some of the most extreme events in the cosmos.

In addition to its search for the optical counterparts to gravitational waves, BlackGEM will also perform surveys of the southern sky. Its operations are fully automated, meaning the array can quickly find and observe ‘transient’ astronomical events, which appear suddenly and quickly fade out of view. This will give astronomers deeper insight into short-lived astronomical phenomena such as supernovae, the huge explosions that mark the end of a massive star’s life. 

“BlackGEM is opening a new window for time-domain astronomy in Southern Hemisphere,” says Nadejda Blagorodnova, researcher at the Institute of Cosmos Sciences of the University of Barcelona and the Institute of Space Studies of Catalonia (ICCUB-IEEC), who is taking part on the project. “It will allow us to search for light emitted by gravitational wave events. It will also closely monitor a large number of nearby galaxies, which means that if any supernova or stellar merger occurs there, we will be able to find it almost in real-time and possibly identify its progenitor system!”

More information
 

The BlackGEM consortium comprises: NOVA (Netherlands Research School for Astronomy, the national Dutch alliance in astronomy between the University of Amsterdam, University of Groningen, Leiden University, and Radboud University); Radboud University, the Netherlands; KU Leuven, Belgium; the Weizmann Institute, the Hebrew University of Jerusalem and Tel Aviv University, Israel; the University of Manchester and the Armagh Observatory and Planetarium, UK; Texas Tech University, the University of California at Davis and the Las Cumbres Observatory, USA; the University of Potsdam, Germany; the Danish Technical University, Denmark; the Institute of Cosmos Sciences of the University of Barcelona, Spain; and the University of Valparaíso, Chile.

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society. 

Links
 

• BlackGEM on the ESO website
• BlackGEM website
• ESO Telescopes Observe First Light from Gravitational Wave Source (press release)

Globular clusters are the most massive and oldest star clusters in the Universe. They can contain up to 1 million of them. The chemical composition of these stars, born at the same time, shows anomalies that are not found in any other population of stars. Explaining this specificity is one of the great challenges of astronomy. After having imagined that supermassive stars could be at the origin, a team from the Universities of Geneva and Barcelona, and the Institut d’Astrophysique de Paris (CNRS and Sorbonne University) believes it has discovered the first chemical trace attesting to their presence in globular proto-clusters, born about 440 million years after the Big Bang. These results, obtained thanks to observations by the James-Webb space telescope, are to be found in Astronomy and Astrophysics.

Monsters with very short lives

A team from the universities of Geneva (UNIGE) and Barcelona, and the Institut d’Astrophysique de Paris (CNRS and Sorbonne University) has made a new advance in the explanation of this phenomenon. In 2018, it had developed a theoretical model according to which supermassive stars would have «polluted» the original gas cloud during the formation of these clusters, enriching their stars with chemical elements in a heterogeneous manner. ‘‘Today, thanks to the data collected by the James-Webb Space Telescope, we believe we have found a first clue of the presence of these extraordinary stars,’’ explains Corinne Charbonnel, a full professor in the Department of Astronomy at the UNIGE Faculty of Science, and first author of the study.

These celestial monsters are 5 000 to 10 000 times more massive and five times hotter at their centre (75 million °C) than the Sun. But proving their existence is complex. ‘‘Globular clusters are between 10 and 13 billion years old, whereas the maximum lifespan of superstars is two million years. They therefore disappeared very early from the clusters that are currently observable. Only indirect traces remain,’’ explains Mark Gieles, ICREA professor at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB-IEEC) and co-author of the study.

Revealed by light

Thanks to the very powerful infrared vision of the James-Webb telescope, the co-authors were able to support their hypothesis. The satellite captured the light emitted by one of the most distant and youngest galaxies known to date in our Universe. Located at about 13.3 billion light-years, GN-z11 is only a few tens of millions of years old. In astronomy, the analysis of the light spectrum of cosmic objects is a key element in determining their characteristics. Here, the light emitted by this galaxy has provided two valuable pieces of information.

‘‘It has been established that it contains very high proportions of nitrogen and a very high density of stars,’’ says Daniel Schaerer, associate professor in the Department of Astronomy at the UNIGE Faculty of Science, and co-author of the study. This suggests that several globular clusters are forming in this galaxy and that they still harbour an active supermassive star. ‘‘The strong presence of nitrogen can only be explained by the combustion of hydrogen at extremely high temperatures, which only the core of supermassive stars can reach, as shown by the models of Laura Ramirez-Galeano, a Master’s student in our team,’’ explains Corinne Charbonnel.

These new results strengthen the international team’s model. The only one currently capable of explaining the abundance anomalies in globular clusters. The next step for the scientists will be to test the validity of this model on other globular clusters forming in distant galaxies, using the James-Webb data.

At the end of their lives, massive stars usually undergo core-collapse and explode in a highly energetic burst called supernova. However, what happens to very massive stars with more than 100 times the mass of the Sun? How do they evolve and explode? How are they related to the brightest supernovae in the universe - superluminous supernovae (SLSNe)?

Prof. Xiaofeng Wang's team of Tsinghua University, in collaboration with national and international research teams, has monitored the nearby superluminous supernova SN2017egm for more than one year, revealing its extremely complex luminosity evolution (Figure 1).

By fitting the total luminosity evolution of the object with various kinds of energy source models, the team found that such a “bumpy” light curve mainly originated from the interaction of material ejected during the supernova explosion with four shells of circumstellar material (CSM). The existence of these CSM shells reveals that, right before the final collapse, the progenitor star of the supernova experienced frequent mass ejections with an average rate of 1-10 solar masses per year. Such a frequent and massive mass ejection is inconsistent with ordinary stellar wind and binary interaction models, but they are likely driven by a mechanism called pulsational pair-instability (PPI). 

Combining these models, the initial core of the star is estimated to be about 50 solar masses. This core lost 7-8 solar masses during the PPI phase, when it produced the four shells of circumstellar material, and it ejected 2-3 solar masses of material in the final burst. During this last phase, the ejected material interacted with the pre-existing circumstellar shells powering one of the most luminous stellar explosions observed in our Universe and leaving behind a corpse consisting of a black hole of about 40 solar masses. 

This has important implications for the formation of the tens of solar masses black holes, which have been recently detected by LIGO-Virgo gravitational wave observatories. This work shows that such heavy black holes can be produced through the mentioned mechanisms, and not only via the merger of lighter black holes.

In order to trigger the PPI mechanism, stars need to have a very heavy helium core, which, according to the single stellar evolution theory, usually evolves from a massive star with a low metal abundance. However, the progenitor star of SN2017egm is located in a metal-rich environment, which opens up many questions about its mysterious origin.

“We got really excited about SN2017egm, because in contrast to previous superluminous supernovae, which usually exploded in dwarf galaxies, its host was a large spiral galaxy. This challenged all our previous assumptions about how SLSNe are formed.” said Nadia Blagorodnova, member of ICCUB who contributed to the study.

This supernova could have originated from a metal-rich progenitor with greatly reduced mass-loss rate before oxygen burning stage, or a metal-poor star that somehow exploded in a metal-rich host galaxy, or even from the merger product of two massive stars. Which one of these scenarios is most plausible is still to be seen. 

“The research of this supernova is of great significance for testing current theory of stellar evolution and explosion, and for understanding the origin of superluminous supernovae and massive stellar-mass black holes”, says Dr. Lin, lead author of this work.

Collaborators

The collaborators of this paper include Prof. Xiaofeng Wang's research team at Tsinghua University, Dr. Lin Yan and her colleagues at California Institute of Technology, Prof. Avishay Gal-Yam of Weizmann Institute of Science, Prof. Alexei Filippenko’s research team at University of California, Berkeley, Dr. Ragnhild Lunnan at Stockholm University, Prof. Shuhrat A. Ehgamberdiev's research team at Ulugh Beg Astronomical Institute and National University of Uzbekistan, Prof. Licai Deng’s team at China West Normal University, Dr. Nadejda Blagorodnova at the Institute of Cosmos Sciences of the University of Barcelona, Dr. Jicheng Zhang at Beijing Normal University, Prof. Jujia Zhang at Yunnan Observatories, Dr. Peter Brown at Texas A&M University, Prof. Lin Xiao at Hebei University and Dr. Lingjun Wang at Institute of High Energy Physics. The work of Prof. Xiaofeng Wang is supported by the National Natural Science Foundations of China, the Scholar Program of Beijing Academy of Science and Technology and the Tencent Xplorer Prize.

References:

Lin, W., Wang, X., Yan, L. et al. A superluminous supernova lightened by collisions with pulsational pair-instability shells. Nat Astron (2023). https://doi.org/10.1038/s41550-023-01957-3

An international team of European astronomers using the James Webb Space Telescope (JWST) of NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA) has detected an extremely small and previously unknown asteroid. At 100 to 200 metres in diameter, the object is probably the smallest observed to date by Webb within the main asteroid belt, located between Mars and Jupiter.

The work, which was published on Astronomy & Astrophysics, counts with the participation of researcher Toni Santana-Ros of the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), the Institute of Space Studies of Catalonia (IEEC) and the University of Alicante. 

The detection of this asteroid has relevant implications for understanding the formation and evolution of the Solar System. Current models predict the presence of very small asteroids, but they have not been studied in as much detail as their larger counterparts due to the great difficulty in observing them. In this sense, the great novelty of this finding lies in the fact that the research team has used a new technique to detect and characterise small objects with the data generated by the James Webb Telescope: the MIRI (Mid-InfraRed Instrument) calibration based on infrared wavelengths. 

According to Thomas Müller, an astronomer at the Max Planck Institute for Extraterrestrial Physics (Germany), they have quite unexpectedly detected a small asteroid in the publicly available MIRI calibration observations. In order to detect such a body with ground-based optical telescopes, more than an hour of observations with the largest telescopes available would have been required. However, with Webb, the largest and most powerful telescope ever launched into space, the object is visible in just a few minutes of observation, as explained by Toni Santana-Ros (ICCUB-IEEC-UA), who is co-author of the study. 

A priori, the team could not know whether the detected object was very small and far away or very large and close. The novelty of the method used lies in the fact that the researchers have combined measurements of the position of the observed object with the constraints due to the thermal model derived from the JWST infrared observations. In this way, we were able to define the distance to the object and its size, Santana-Ros said. 

The Webb observations that revealed this small asteroid were not originally designed to hunt for new asteroids - in fact, they were calibration images of the main-belt asteroid 10920, which astronomers discovered in 1998. But the JWST calibration team considered them to have failed for technical reasons due to the brightness of the target and a shift in the telescope pointing. Nevertheless, they used the data from asteroid 10920 to establish and test the new technique for constraining the orbit of an object and estimating its size. The validity of the method was demonstrated for asteroid 10920 using MIRI observations combined with data from ground-based telescopes and ESA's Gaia mission. 

During the analysis of the MIRI data, astronomers discovered an asteroid in the same field of view that was much smaller than 10920 and previously unknown. The results of the work suggest that the object is between 100 and 200 metres long, which occupies a very low-inclination orbit, and is in the inner region of the main belt at the time of the Webb observations. 

The Solar System is full of asteroids and small rocky bodies: astronomers currently know of more than 1.1 million such remnants from the early Solar System. The ability of NASA, ESA and CSA's James Webb Space Telescope to explore these objects at infrared wavelengths is expected to lead to groundbreaking new scientific discoveries. 

The international team of astronomers involved in this study includes Toni Santana-Ros from the University of Alicante and University of Barcelona; P. Bartczak from the University of Alicante and A. Mickiewicz University (Poland); T. G. Müller and S. Kruk from the Max Planck Institute for Extraterrestrial Physics (Germany); M. Micheli from ESA's NEO Coordination Centre (Italy); and D. Oszkiewicz from A. Mickiewicz University (Poland).

Reference: 

“Asteroids seen by JWST-MIRI: Radiometric size, distance, and orbit constraints”, Astronomy & Astrophysics (2023) DOI: 10.1051/0004-6361/202245304

Further information

ESA/Webb 

Webb Space Telescope

Barcelona, 12 December, 2022. The Isaac Newton Group of Telescopes (ING) and the WEAVE instrument team present observations of the first light with the WEAVE spectrograph. WEAVE is a powerful new generation multifibre spectrograph in the William Herschel Telescope (WHT) at the Roque de los Muchachos Observatory (La Palma, Canary Islands) which has recently been launched and is already generating high-quality data.

Astronomers from all over Europe have planned eight surveys for observation with WEAVE, including studies of stellar evolution, the Milky Way, the galaxy evolution and cosmology. In line with the European Space Agency's Gaia satellite, WEAVE will be used to obtain spectra of several million stars in the disc and halo of our galaxy, enabling the archaeology of the Milky Way. Nearby and distant galaxies will be studied to know the history of their growth. And quasars will be used as indications to map the spatial distribution and interaction of gas and galaxies when the universe was only about 20% of today's age.

First light observations: Stephan's Quintet galaxies

WEAVE targeted NGC 7318a and NGC 7318b, two galaxies at the centre of Stephan's Quintet, a group of interacting galaxies. This group had already been observed with the Hubble, Spitzer and Chandra telescopes, among others, and more recently also with the James Webb Space Telescope (JWST). It is also famous for its role in the 1946 Christmas film It's a Wonderful Life. Its galaxies, four of which are 280 million light-years from Earth, are colliding with each other, providing an excellent "close-up" laboratory for studying the consequences of galaxy collisions and subsequent evolution.

The observations of the first light were carried out with the so-called Large Integral Field Unit (LIFU) fibre array, one of WEAVE’s three fibre systems. When using the LIFU, 547 very compact optical fibres transmit the light from a hexagonal area of the sky to the spectrograph, where it is analysed and recorded.

WEAVE’s LIFU has measured a large number of individual spectra of the two central galaxies of Stephan's quintet and their surroundings, and has examined the intensity of the colours of their light, from the ultraviolet to the near-infrared. These spectra reveal, among other information, details essential for studying the collision processes, such as the motion and distribution of stars and gas, and their chemical composition. From these data, we can learn how galaxy collisions transform the other galaxies in the group.

Marc Balcells, ING director, explains: "Our goal has been to install a unique instrument that will allow us to carry out cutting-edge astronomical research. It has been fantastic to receive financial support from the national research agencies of the three ING partner countries (UK, Spain and the Netherlands), as well as contributions from other non-ING countries (France and Italy). We are pleased to demonstrate that the LIFU part of WEAVE not only works, but produces high-quality data. The ING telescopes will continue to deliver results of high scientific impact in the coming years. We look forward to announcing soon the first-light events for the other observing modes, which are currently in the final calibration phase”.

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, two ICCUB-IEEC members, Maria Monguió and 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 and Ignasi Pérez-Ràfols, also from the ICCUB-IEEC, co-lead the research teams responsible for galactic disc dynamics and quasars, respectively.

Maria Monguió, from the Institute of Cosmos Sciences (ICCUB-IEEC), says: "After years of preparation, we hope to soon be able to obtain the first spectra of stars in the disc of our galaxy. The quantity and quality of the millions of spectra we expect to observe will allow us, among other things, to analyse regions of recent star formation and to measure how stars move. These data, together with those provided by the Gaia mission, will allow us to address fundamental questions about the formation and evolution of the Milky Way”.

Roberto Raddi, commenting on the contribution of the Polytechnic University of Catalonia, says: "Our team will contribute to the study of some 100,000 white dwarfs previously observed by Gaia, and discover the secrets behind the last evolutionary phases of Sun-like stars, including the fate of their planetary systems, as well as the mechanisms that lead to supernova explosions in binary systems with white dwarfs".

Further information:

https://www.ing.iac.es/PR/press/weave_LIFU_first_light.html

http://arxiv.org/abs/2212.03981

Press Office

University of Barcelona

+34 934 035 544

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Dr. Carla Marín, a researcher at the Experimental Particle Physics Group at the Institute of Cosmos Science of the University of Barcelona (ICCUB), has been awarded an ERC Starting Grant with more than 1.6M€ to carry out her project “Challenging the Standard Model with suppressed b to d ll decays (CLIMB)”.

ERC Starting Grants, which are part of the program Horizon Europe, are designed to help talented researchers who want to establish their research teams in Europe. The awarded candidates must have an excellent scientific track record showing scientific talent and an excellent research proposal for the next five years. These are evaluated on the basis of excellence as the sole criterion by selected international peer reviewers.

 About the CLIMB project 

The Standard Model of Particle Physics is one of the most complete scientific theories we have developed so far. Despite its hugely successful predictive power, it still fails to explain some observations that are key to understanding our Universe, such as the dominance of matter over antimatter. In the Large Hadron Collider (LHC) at CERN, the LHCb experiment studies decays of b quarks, which result from the proton collisions. The CLIMB project focuses on the rare decays which are those that occur less than once in every million decays. The scarcity of these decays makes them very sensitive to the existence of new particles and forces beyond the Standard Model, which can modify their properties. In recent years, a set of deviations from the predictions of the Standard Model have been observed in the decays of b quarks to an s quark and two leptons, electrons or muons, (b -> s ll), which could be an indication of the existence of new physics.

 The CLIMB project will explore even rarer decays of the b quark to a d quark and two leptons (b -> d ll), which occur once in 100 million. The b -> dll transitions are related to the b -> s ll transitions through the Cabibbo–Kobayashi–Maskawa (CKM) matrix that describes quark mixing in the Standard Model, but their hierarchy is not well understood. Explaining the origin of this hierarchy is the motivation for many new physics models, and therefore, accurately measuring the relationship between b -> sll and b -> dll decays is key information for these models. Due to its suppression, to this day we have very little experimental information on b -> dll transitions. CLIMB aims to radically change this situation. To this end, Dr. Marín’s team will use unique data from the LHCb experiment which contain billions of b quarks, and develop new reconstruction and analysis techniques in order to observe and measure the properties of these sneaky decays.

In the words of Dr. Marín, “due to the rarity of these decays and the difficulty of measuring electrons at the LHCb experiment, new techniques of particle reconstruction and data analysis need to be developed, and here is where the challenge really lies. If we succeed, we will be able to compare transitions with muons and electrons, which should occur exactly the same number of times but which recent experiments indicate may not be the case. This would be clear evidence for the existence of Physics beyond the Standard Model.”

About Dr. Carla Marín

Carla Marín joined the Experimental Particle Physics Group at the Institute of Cosmos Sciences of the University of Barcelona in 2013 to initiate her doctoral thesis with prof. Lluís Garrido.

After obtaining her doctorate, she was a postdoctoral researcher at the Laboratoire de l'Accélérateur Linéaire, Orsay (2018-2021) and CERN (2021-2022).

In 2022, she rejoined the ICCUB where she is currently a tenure-track lecturer.

Outside Particle Physics, Carla Marin enjoys chess and playing football with colleagues from the Physics faculty at the regular weekly matches.

The Gaia collaboration, which is responsible for the spacecraft that is currently building the largest and most precise three-dimensional map of our galaxy, will receive the 2023 Lancelot M. Berkeley − New York Community Trust Prize for Meritorious Work in Astronomy. Bestowed annually since 2011 by the American Astronomical Society (AAS) and supported by a grant from the New York Community Trust, the Berkeley prize includes a monetary award and an invitation to give the closing plenary lecture at the AAS winter meeting, often called the “Super Bowl of Astronomy.” The 241st AAS meeting will be held in Seattle, Washington, from 8 to 12 January 2023.

The Gaia collaboration is being honored with the 2023 Berkeley prize for enabling a transformative, multidimensional map of the Milky Way. Since its launch in 2013, the European Space Agency’s Gaia space telescope has recorded stellar positions, distances, colors, and proper motions for nearly two billion stars in our galaxy. According to the prize statement, “Gaia’s three data releases will long be regarded as major events in the history of astronomy, triggering a global partnership to better understand the origin, structure, and destiny of our home galaxy.”

Each year the three AAS Vice Presidents, in consultation with the Editor in Chief of the AAS journals, select the Berkeley prize winner for meritorious research published within the preceding 12 months. The Gaia team is recognized in particular for an article published in Astronomy & Astrophysics in May 2021 describing the early contents and survey properties behind the Gaia mission’s most recent data release.

The exquisite precision and immense volume of the Gaia’s survey has entirely transformed the way stellar and galactic astronomy is conducted. The mission’s three data releases thus far encompass the largest low-resolution spectroscopic and radial velocity surveys in history, capturing detailed information and mapping roughly 1.8 billion Milky Way stars, including 10 million variable stars and 813,000 binary systems. In addition, the mission is enabling advances in both extragalactic and solar system science: it has cataloged 3 million galaxies, 2 million quasars (distant and bright galactic nuclei), and 156,000 solar system objects, including near-Earth and main-belt asteroids and trans-Neptunian objects. 

The Gaia’s full third data release, which was welcomed worldwide on 13 June 2022, was accompanied by nearly 50 scientific articles by the Gaia collaboration. Reflective of the mission’s impact on the science of astronomy, this immense body of work includes the highest cited papers in all of astronomy over the past year.

“The AAS and the New York Community Trust send our gratitude and congratulations to the many hundreds of scientists, engineers, and program/technical/support personnel at the European Space Agency and far beyond for bringing this transformative mission to life. Gaia will forever remain a landmark achievement in humanity’s story of cosmic exploration,” the AAS Vice Presidents commented in a statement.

The Gaia data catalogs are produced by the Gaia Data Processing and Analysis Consortium (DPAC), a collaboration that consists of hundreds of scientists and engineers from around the world. The Berkeley Prize will be accepted on behalf of the Gaia collaboration by Anthony Brown (Leiden Observatory), Chair of the DPAC Executive, and he will give the prize lecture on Thursday afternoon, 12 January 2023, at the Seattle Convention Center.

Spanish contribution to Gaia

A number of Spanish institutions are participating actively in the Gaia Collaboration including the Institute of Cosmos Sciences of the University of Barcelona (ICCUB-IEEC), which is leading the Spanish contribution, the University of A Coruña (UdC), the University of Vigo (UVigo) and the Barcelona Supercomputing Center (BSC-CNS).

The role of the ICCUB-IEEC team focused on the scientific and technological design of the project, the development of the data processing system and the production of simulated data. A part of the software for the processing of the data sent by the satellite has been developed by the ICCUB-IEEC team and is executed at the MareNostrum Supercomputer, of the Barcelona Supercomputing Center (BSC-CNS). 

A team of international experts, renowned for debunking several black hole discoveries, have found a stellar-mass black hole in the Large Magellanic Cloud, a neighbour galaxy to our own. "For the first time, our team got together to report on a black hole discovery, instead of rejecting one," says study leader Tomer Shenar. Moreover, they found that the star that gave rise to the black hole vanished without any sign of a powerful explosion. The discovery was made thanks to six years of observations obtained with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT).

“We identified a ‘needle in a haystack’,” says Shenar who started the study at KU Leuven in Belgium [1] and is now a Marie-Curie Fellow at Amsterdam University, the Netherlands. Though other similar black hole candidates have been proposed, the team claims this is the first ‘dormant’ stellar-mass black hole to be unambiguously detected outside our galaxy.

Stellar-mass black holes form when massive stars reach the end of their lives and collapse under their own gravity. In a binary, a system of two stars revolving around each other, there is the chance of finding a black hole from the motion of a luminous companion star. “From the nearly circular orbit of this binary, we could conclude that this black hole did not receive a velocity kick when it formed in a supernova explosion, a fact that will help us get a better understanding of the origin of gravitational waves detected by the LIGO-Virgo detectors”, comments ICREA Professor Mark Gieles from the ICCUB. He is a co-author on the paper, and leads the Virgo gravitational wave research group of the ICCUB, who analyse and interpret the rapidly growing number of detected compact object collisions, such as binary black holes. 

The black hole is ‘dormant’ if it does not emit high levels of X-ray radiation, which is how such black holes are typically detected. “It is incredible that we hardly know of any dormant black holes, given how common astronomers believe them to be”, explains co-author Pablo Marchant of KU Leuven. The newly found black hole is at least nine times the mass of our Sun, and orbits a hot, blue star weighing 25 times the Sun’s mass.

Dormant black holes are particularly hard to spot since they do not interact much with their surroundings. “For more than two years now, we have been looking for such black-hole-binary systems,” says co-author Julia Bodensteiner, a research fellow at ESO in Germany. “I was very excited when I heard about VFTS 243, which in my opinion is the most convincing candidate reported to date.” [2]

To find VFTS 243, the collaboration searched nearly 1000 massive stars in the Tarantula Nebula region of the Large Magellanic Cloud, looking for the ones that could have black holes as companions. Identifying these companions as black holes is extremely difficult, as so many alternative possibilities exist.

“As a researcher who has debunked potential black holes in recent years, I was extremely sceptical regarding this discovery,” says Shenar. The scepticism was shared by co-author Kareem El-Badry of the Center for Astrophysics | Harvard & Smithsonian in the USA, whom Shenar calls the “black hole destroyer”. “When Tomer asked me to double check his findings, I had my doubts. But I could not find a plausible explanation for the data that did not involve a black hole,” explains El-Badry.

The discovery also allows the team a unique view into the processes that accompany the formation of black holes. Astronomers believe that a stellar-mass black hole forms as the core of a dying massive star collapses, but it remains uncertain whether a powerful supernova explosion accompanies this.

"The star that formed the black hole in VFTS 243 appears to have collapsed entirely, with no sign of a previous explosion," explains Shenar. "Evidence for this ‘direct-collapse’ scenario has been emerging recently, but our study arguably provides one of the most direct indications. This has enormous implications for the origin of black-hole mergers in the cosmos."

The black hole in VFTS 243 was found using six years of observations of the Tarantula Nebula by the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument on ESO’s VLT [3].

Despite the nickname ‘black hole police’, the team actively encourages scrutiny, and hopes that their work, published today in Nature Astronomy, will enable the discovery of other stellar-mass black holes orbiting massive stars, thousands of which are predicted to exist in Milky Way and in the Magellanic Clouds.

“Of course I expect others in the field to pore over our analysis carefully, and to try to cook up alternative models,” concludes El-Badry. “It's a very exciting project to be involved in.”

Notes

[1] The work was conducted in the team lead by Hugues Sana at KU Leuven’s Institute of Astronomy. 

[2] A separate study led by Laurent Mahy, involving many of the same team members and accepted for publication in Astronomy & Astrophysics, reports on another promising stellar-mass black hole candidate, in the HD 130298 system in our own Milky Way galaxy.

[3] The observations used in the study cover about six years: they consist of data from the VLT FLAMES Tarantula Survey (led by Chris Evans, United Kingdom Astronomy Technology Centre, STFC, Royal Observatory, Edinburgh; now at the European Space Agency) obtained from 2008 and 2009, and additional data from the Tarantula Massive Binary Monitoring programme (led by Hugues Sana, KU Leuven), obtained between 2012 and 2014.

More information

This research was presented in a paper titled “An X-ray quiet black hole born with a negligible kick in a massive binary of the Large Magellanic Cloud” to appear in Nature Astronomy (doi: 10.1038/s41550-022-01730-y).

The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement numbers 772225: MULTIPLES) (PI: Sana).

The team is composed of T. Shenar (Institute of Astronomy, KU Leuven, Belgium [KU Leuven]; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, the Netherlands [API]), H. Sana (KU Leuven), L. Mahy (Royal Observatory of Belgium, Brussels, Belgium), K. El-Badry (Center for Astrophysics | Harvard & Smithsonian, Cambridge, USA [CfA]; Harvard Society of Fellows, Cambridge, USA; Max Planck Institute for Astronomy, Heidelberg, Germany [MPIA]), P. Marchant (KU Leuven), N. Langer (Argelander-Institut für Astronomie der Universität Bonn, Germany, Max Planck Institute for Radio Astronomy, Bonn, Germany [MPIfR]), C. Hawcroft (KU Leuven), M. Fabry (KU Leuven), K. Sen (Argelander-Institut für Astronomie der Universität Bonn, Germany,  MPIfR), L. A. Almeida (Universidade Federal do Rio Grande do Norte, Natal, Brazil; Universidade do Estado do Rio Grande do Norte, Mossoró, Brazil), M. Abdul-Masih (ESO, Santiago, Chile), J. Bodensteiner (ESO, Garching, Germany), P. Crowther (Department of Physics & Astronomy, University of Sheffield, UK), M. Gieles (ICREA, Barcelona, Spain; Institut de Ciències del Cosmos, Universitat de Barcelona, Barcelona, Spain), M. Gromadzki (Astronomical Observatory, University of Warsaw, Poland [Warsaw]), V. Henault-Brunet (Department of Astronomy and Physics, Saint Mary’s University, Halifax, Canada), A. Herrero (Instituto de Astrofísica de Canarias, Tenerife, Spain [IAC]; Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain [IAC-ULL]), A. de Koter (KU Leuven, API), P. Iwanek (Warsaw), S. Kozłowski (Warsaw), D. J. Lennon (IAC, IAC-ULL), J. Maíz Apellániz (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), P. Mróz (Warsaw), A. F. J. Moffat (Department of Physics and Institute for Research on Exoplanets, Université de Montréal, Canada), A. Picco (KU Leuven), P. Pietrukowicz (Warsaw), R. Poleski (Warsaw), K. Rybicki (Warsaw and Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Israel), F. R. N. Schneider (Heidelberg Institute for Theoretical Studies, Heidelberg, Germany [HITS]; Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Heidelberg, Germany), D. M. Skowron (Warsaw), J. Skowron (Warsaw), I. Soszyński (Warsaw), M. K. Szymański (Warsaw), S. Toonen (API), A. Udalski (Warsaw), K. Ulaczyk (Department of Physics, University of Warwick, UK), J. S. Vink (Armagh Observatory & Planetarium, UK), and M. Wrona (Warsaw).

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Contacts

Tomer Shenar
KU Leuven and University of Amsterdam
Leuven and Amsterdam, Belgium and The Netherlands
Email: t.shenar@uva.nl

Julia Bodensteiner
European Southern Observatory
Garching bei München, Germany
Tel: +49-89-3200-6409
Email: julia.bodensteiner@eso.org

Kareem El-Badry
Center for Astrophysics | Harvard & Smithsonian
Cambridge, USA
Email: kareem.el-badry@cfa.harvard.edu

Pablo Marchant
KU Leuven
Leuven, Belgium
Tel: +32 16 33 05 47
Email: pablo.marchant@kuleuven.be

Hugues Sana
KU Leuven
Leuven, Belgium
Tel: +32 479 50 46 73
Email: hugues.sana@kuleuven.be

Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org

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