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A team of astronomers has discovered 83 quasars powered by supermassive black holes (SMBHs) in the distant universe, from an epoch when the universe was less than 10 percent of its present age. This finding increases the number of black holes known at that epoch considerably, and reveals, for the first time, how common SMBHs are early in the universe’s history. In addition, it provides new insight into the effect of black holes on the physical state of gas in the early universe in its first billion years. Figure 1 shows an example of a discovered SMBH.
CREDIT: National Astronomical Observatory of Japan
Figure 1.Light from one of the most distant quasars known, powered by a SMBH lying 13.05 billion light-years away from Earth. The image was obtained by the Hyper Suprime-Cam (HSC) mounted on the Subaru Telescope. The other objects in the field are mostly stars in our Milky Way, and galaxies seen along the line of sight.
| Supermassive black holes are found at the centers of galaxies, and have masses millions or even billions of times that of the Sun. While they are prevalent in the present-day universe, it is unclear when they first formed, and how many of them exist in the distant early universe. While distant SMBHs are identified as quasars, which shine as gas accretes onto them (see Figure 2 for an artist impression), previous studies have been sensitive only to the very rare most luminous quasars, and thus the most massive black holes. The new discoveries probe the population of SMBH with masses characteristic of the most common black holes seen in the present-day universe, and thus shed light on their origin. |
The research team led by Yoshiki Matsuoka (Ehime University) used data taken with a cutting-edge instrument, “Hyper Suprime-Cam” (HSC), mounted on the Subaru Telescope of the National Astronomical Observatory of Japan, on the summit of Maunakea in Hawai’i. HSC is particularly powerful in that it has a gigantic field-of-view of 1.77 deg 2 (seven times the area of the Full Moon), mounted on one of the largest telescopes in the world. The HSC team is carrying a survey of the sky using 300 nights of telescope time, spread over five years. The team selected distant quasar candidates from the sensitive HSC survey data. They then carried out an intensive observational campaign to obtain spectra of those candidates, using the SubaruTelescope, the Gran Telescopio Canarias, and the Gemini telescope. The survey has revealed 83 previously unknown very distant quasars; together with the 17 quasars already known in the survey region, Matsuoka and collaborators found that there is roughly one supermassive black hole in each cube a billion light years on a side. Figure 3 shows images of the 100 quasars identified from the HSC data.
CREDIT: National Astronomical Observatory of Japan
Figure 3.Light from one of the most distant quasars known, powered by a SMBH lying 13.05 billion light-years away from Earth. The image was obtained by the Hyper Suprime-Cam (HSC) mounted on the Subaru Telescope. The other objects in the field are mostly stars in our Milky Way, and galaxies seen along the line of sight.
The discovered quasars are about 13 billion light-years away from the Earth; in other words, we are seeing them as they existed 13 billion years ago. The time elapsed since the Big Bang to that cosmic epoch is only 5 per cent of the present cosmic age (13.8 billion years), and it is remarkable that such massive dense objects were able to form so soon after the Big Bang. The most distant quasar discovered by the team is 13.05 billion light-years away, which is tied for the second most distant SMBH ever discovered.
It is widely accepted that the hydrogen in the universe was once neutral, but was “reionized” (i.e., split into its component protons and electrons) around the epoch when the first generation of stars, galaxies, and SMBHs were born, in the first few hundred million years after the Big Bang. This is a milestone of cosmic history, but it is still not clear what provided the incredible amount of energy required to cause the reionization. A compelling hypothesis suggests that there were many more quasars in the early universe than detected previously, and it is their integrated radiation that reionized the universe. However, the number density measured by the HSC team clearly indicates that this is not the case; the number of quasars seen is significantly less than needed to explain the reionization. Reionization was therefore caused by another energy source, most likely numerous galaxies that started to form in the young universe.
The present study was made possible by the world-leading survey ability of Subaru and HSC. The intensive follow-up observations by the Subaru Telescope, Gran Telescopio Canarias, and the Gemini telescope were another key to success. “The quasars we discovered will be an interesting subject for further follow-up observations with current and future facilities.”, said Matsuoka. “We will also learn about the formation and early evolution of SMBHs, by comparing the measured number density and luminosity distribution with predictions from theoretical models.” Based on the results achieved so far, the team is looking ahead to search for yet more distant SMBHs, and to reveal the epoch when the first SMBH appeared in the universe.
The research team consists of 48 astronomers around the world. Matsuoka led the team, while Nobunari Kashikawa (The University of Tokyo), Michael Strauss (Princeton University), Masafusa Onoue (Max Planck Institute for Astronomy), Kazushi Iwasawa (Universitat de Barcelona), and Tomotsugu Goto (National Tsing Hua University) have played key roles in the individual steps of the project. The results of the project are presented in the following five papers (paper [2] in particular).
[1] “Discovery of the First Low-luminosity Quasar at z > 7”, Matsuoka et al., The Astrophysical Journal Letters, 872 (2019), 2
[2] “Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). V. Quasar Luminosity Function and Contribution to Cosmic Reionization at z = 6”, Matsuoka et al. 2018, The Astrophysical Journal, 869 (2018), 150
[3] “Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). IV. Discovery of 41 Quasars and Luminous Galaxies at 5.7 ≤ z ≤ 6.9”, Matsuoka et al., The Astrophysical Journal Supplement Series, 237 (2018), 5
[4] “Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). II. Discovery of 32 quasars and luminous galaxies at 5.7 < z ≤ 6.8”, Matsuoka et al., Publications of the Astronomical Society of Japan, 70 (2018), S35
[5] “Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). I. Discovery of 15 Quasars and Bright Galaxies at 5.7 < z < 6.9”, Matsuoka et al., The Astrophysical Journal, 828 (2016), 26
More specificaly, Kazushi Iwasawa has contributed in the quasar discovery, which consist of two phases: 1) selecting candidates using images from the Subaru telescope and, 2) verify the quasar identity and evaluate the distance with other data. In the second phase, the data was obtained with the Subaru and the Gran Canarias Telescope (GTC). Kazushi Iwasawa was the main investigator in the observations made at the Gran Canarias Telescope, from which a 1/3 of the quasars were discovered.
The HSC collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. The HSC instrumentation and software were developed by the National Astronomical Observatory of Japan (NAOJ), the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the University of Tokyo, the High Energy Accelerator Research Organization (KEK), the Academia Sinica Institute for Astronomy and Astrophysics in Taiwan (ASIAA), and Princeton University. Funding was contributed by the FIRST program from Japanese Cabinet Office, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japan Society for the Promotion of Science (JSPS), Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University.
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Astronomers discover 83 supermassive black holes in the earl
The EuropeanSpace Agency (ESA) Gaia mission, by combining new data from with observations made with the NASA/ESA Hubble Space Telescope, have found that the Milky Way weighs in at about 1.5 trillion solar masses within a radius of 129000 light-years from the galactic centre.
Themass of the Milky Way is considered as one of the most fundamental measurements astronomers can make about our galactic home. Previous estimates of the mass ofthe Milky Way ranged from 500 billion to 3 trillion times the mass of the Sun, being a subject of disagreement between researchers. This huge uncertainty arose primarily from the different methods used for measuring the distributionof dark matter – which makes up about 90% of the mass of the galaxy. Laura Watkins (European Southern Observatory, Germany), who led the team performing the analysis, considers that the inability to detect dark matter is the cause of that uncertainty.
Given the elusive nature of the dark matter, the team had to use a clever method to weigh the Milky Way, which relied on measuring the velocities of globular clusters – dense star clusters that orbit the spiral disc of the galaxy at great distances.
In words of Professor N. Wyn Evans (University of Cambridge, UK) says that "Most previous measurements have foundthe speed at which a cluster is approaching or receding from Earth, that is the velocity along our line of sight. However, we were able to also measure the sideways motion of the clusters, from which the total velocity, and consequently the galactic mass, can be calculated."
The group used Gaia's second data release as a basis fortheir study. Gaia was designed to create a precise three-dimensional map of astronomical objects throughout the Milky Way and to track their motions. Its second data release includes measurements of globular clusters as far as 65.000 light-years from Earth. The team combined these data with Hubble's unparalleled sensitivity and observational legacy. Observations from Hubble allowed faint and distant globular clusters, as far as 130 000 light-years from Earth, to be added to the study. As Hubble has been observing some of these objects for a decade, it was possible to accurately track the velocities of these clusters aswell.
The dark matter content of a galaxy and its distribution are intrinsically linked to the formation and growth of structures in the Universe. Accurately determining the mass for the Milky Way gives us a clearer understanding of where our galaxy sits in a cosmological context.
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Hubble and Gaia accurately weight the Milky Way
ESA's Gaia satellite is on a mission: to map and characterise more than one billion of the stars in the Milky Way. Many of these stars reside in complex, eye-catching clusters scattered throughout our Galaxy and, by studying these stellar groupings, Gaia is revealing much about the formation and evolution of stars in our cosmic home and surroundings.
The Milky Way is full of stars. Our Galaxy contains over a hundred billion of them, from dwarf to giant, populating its crowded centre and its spiralling disc.
Many of these stars are thought to have formed in the same way: from huge clouds of cool, condensing molecular gas, which collapse under the influence of gravity and fragment to form groups of hundreds to thousands of stars, known as star clusters. Some of these clusters last thousands of millions of years, while others disperse rapidly, releasing their stellar residents into the Milky Way's disc.
It is likely that also our Sun formed in a cluster some 4.5 billion years ago, and the quest for solar siblings – stars that were born in the same cluster as the Sun and then went on different paths – will provide important information on the birth of our parent star.
Despite our growing knowledge, many open questions remain. For instance, how many clusters exist, how many are currently being formed, how many are falling apart – and at what pace?
The incredible diversity of stars and their birth clusters is currently being explored by ESA's Gaia satellite.
Launched in December 2013, Gaia aims to map the nearby cosmos and execute the most extensive census of stars ever performed, tracking the positions, motions, and properties of more than one billion stars in the Milky Way and its surroundings. So far, the mission has released two packages of data: Data Release 1 (DR1) on 14 September 2016, and Data Release 2 (DR2) on 25 April 2018.
"The first release was planned as more of a test release than a full database, and the second is still early days for Gaia," says Carme Jordi of the University of Barcelona, Spain, a member of the Gaia Science Team. "Nonetheless, these datasets have already offered us unique insights into the stars within our Galaxy, and in particular into stellar clusters."
Gaia DR1 contained the positions and brightnesses of 1.1 billion stars, and the parallaxes (a way of measuring distance) and proper motions (movement through the sky) for a subset of two million. Gaia DR2 raises these figures to nearly 1.7 billion stars in terms of positions and brightnesses, over 1.3 billion in terms of parallax and proper motion, and adds new data about stellar colours, line-of-sight velocities, surface temperatures, variability, radii, luminosities, and more.
With Gaia DR2, the mission has provided scientists with new tools to look at star clusters in the Sun's neighbourhood and beyond.
New clusters unveiled
Alfred Castro-Ginard and colleagues
used a statistical method on a subset of Gaia DR1 to discover 21 nearby clusters that had previously gone unnoticed, confirming their findings using the full DR2 data. So far, even if not unanimously, scientists had generally thought that all such clusters out to distances between 3200 and 6500 light-years from Earth had been identified – but this study suggests that there is still much to discover, even in our cosmic neck of the woods.
"It's worth noting that this study only looked at a small part of the sky," explains Jordi. "The discovery of new nearby clusters, which should be the easiest to detect, indicates that our knowledge of these clusters is really quite incomplete out to greater distances."
This finding was soon followed and supported by a different study, led by Tristan Cantat-Gaudin, which re-analysed every previously reported cluster, known and putative alike, using data from Gaia DR2. This research confirmed earlier detections of about 1200 clusters, and determined their average distance and overall motion.
The scientists also serendipitously discovered 60 new potential clusters, but also surprisingly discarded clusters that had previously been identified. The study revealed that many such clusters are actually overlapping groups consisting of more than one cluster, while others are just asterisms – apparent patterns or groupings of stars that are in fact tricks of perspective on the two-dimensional sky.
Another study by Cantat-Gaudin and collaborators focussed on a nearby stellar group known as Vela OB2, which is somewhat looser than an ordinary cluster. Gaia's precision allowed the scientists to study stellar motions within Vela OB2 in great detail, revealing that it comprises multiple smaller clumps of stars and that the overall complex is expanding. They used the data to unravel the history of this stellar group, which is associated with a large, expanding nearby shell of gas known as the IRAS Vela Shell and thought to have originated in a supernova explosion: according to Gaia, the powerful event that triggered this shell also sparked the formation of Vela OB2's stars over 10 million years ago.
"Gaia's extraordinary data are allowing us to revisit our existing stellar census and confirm, discard, and discover clusters," says Jordi, who is a co-author on all three studies. "This is invaluable in helping us to characterise the distribution of clusters throughout the Milky Way's disc, and their height in relation to the Galactic plane."
Tracing clusters along the Gallaxy
On a broader Galactic scale, the new cluster counts that scientist have started to put together with Gaia seems to indicate that clusters sitting high above the plane of the Milky Way are old, and located further from our Galaxy's centre.
"It seems there aren't old clusters at high altitudes in the inner part of the Galactic disc, so they must have dissolved – just as our models predict," explains Jordi.
Looking specifically at clusters in higher-altitude areas of our Galaxy's disc by combining positions and motions on the sky from Gaia DR2 with line-of-sight velocities from a ground-based survey, Janez Kos and colleagues discarded the existence of four out of the five analysed clusters.
In a different study, Caroline Soubiran and colleagues used line-of-sight velocities from Gaia DR2 to explore the kinematics of 861 stellar clusters, and found them to follow the velocity distribution of field stars – stars that are not associated to any cluster – in the solar neighbourhood.
Precise data from Gaia DR2 also contributed to revealing the ongoing evaporation of the nearest cluster to the Sun, the Hyades, in two independent studies led by Stefan Meingast and Siegfried Röser, respectively. This cluster was found to boast two well-defined tidal tails containing hundreds of stars, each extending from the cluster's core in a distinct 'S' shape.
"This unique finding opens a new window for studying how clusters, through their gradual demise under the influence of the Milky Way's gravity, continuously feed the Galactic disc with stars," says Jordi.
Clusters as stellars test-beds
Star clusters are not only tracers of how the disc of our Galaxy has evolved over time, but also excellent laboratories for studying stellar physics. With its unprecedented data, Gaia has started to reveal previously unseen details that have an impact on our understanding of the formation and evolution of stars.
By plotting the colour of stars against their brightness, astronomers have been using the so-called Hertzsprung-Russell (HR) diagram to study the evolution of stellar populations for over a century. In this diagram, most stars lie along a top-left to bottom-right diagonal line known as the 'main sequence' – which identifies stars in their prime, burning hydrogen fuel in their cores – while stars in later stages of their lives are found away from this sequence. In clusters, which were historically thought to contain a single, simple population of stars that formed all at the same time, the position in the diagram where the main sequence 'turns off' was customarily used to estimate the age of that particular stellar population. However, in recent years, scientists had found evidence that clusters may comprise more than one population of stars, based on the observation of multiple turn-off points in their HR diagrams.
Gaia is now calling for a rethink of this phenomenon, as several studies based on its latest dataset seem to indicate how the multiple turn-off points can be explained without invoking several populations of stars, but rather by properly including the effects of the rotation of cluster stars on their predicted colours. For example, Anna Marino and colleagues conducted two studies using photometric data from Gaia DR2 to suggest that this is a common feature in Milky Way clusters, while Beomdu Lim and colleagues found a similar result by combining Gaia proper motions with ground-based spectroscopic observations of M11, also known as the 'Wild Duck' cluster. Similarly, Giacomo Cordoni and colleagues used a mix of stellar velocity, photometry, and proper motion data to confirm that rotational effects of stars can affect their estimated colours and lifespans.
This is certainly not the final word on stellar clusters, and many more studies will follow in coming years and clarify, reopen, and perhaps even deepen these intriguing topics. Like every great mission or experiment, Gaia is providing scientists with precise and plentiful data that are increasing our understanding of many astronomical problems, giving rise to new and more profound questions as our knowledge grows.
"Gaia is unique and revolutionising all fields of astrophysics, with this recent research on star clusters being a good example," says Jos de Bruijne, Gaia deputy project scientist at ESA.
"The mission has given us precise measurements of how stars move through space and their distances from us… and it has done this for over one billion stars. We've never had anything like this database before, and it's invaluable in helping us study our Galaxy.
"The recent star-cluster discoveries make this a hugely exciting area of research – especially as we have more Gaia data releases to look forward to in coming years."
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Rethinking everything we thought we knew about star clusters
Thursday was published an alternative copy of the bulk data files from Gaia DR2. The advantage of this new copy release by DAPCOM Data Services S.L. (a technological spin-off company of the UPC and the UB) is that it allows reducing the total size of Gaia DR2 approximately a 15%.
This copy is easily downloaded and, this fact shows the important work that is doing the Gaia Group to prepare the releases to the public. In addition, it shows a new solution to data compression developed by DAPCOM.
You can now download Gaia DR2 in csv.fapec format here. There you will also find the scripts used for the gzip-to-fapec conversion, as well as the log files from the process.
Free FAPEC decompression licenses can be obtained from the DAPCOM website.
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An alternative copy of the bulk data files from Gaia DR2
Press release by CTA:
| On 17 January 2019, a prototype telescope proposed for the Cherenkov Telescope Array (CTA), the prototype Schwarzschild-Couder Telescope (pSCT) is being unveiled in a special inauguration event at the Center for Astrophysics | Harvard & Smithsonian, Fred Lawrence Whipple Observatory (FLWO) in Amado, Arizona. A dual-mirrored Medium-Sized Telescope, the SCT is proposed to cover the middle of CTA’s energy range (80 GeV – 50 TeV). “The inauguration of the pSCT is an exciting moment for the institutions involved in its development and construction,” said CTA-US Consortium Chair David Williams, a professor of physics at the University of California, Santa Cruz. “The first of its kind in the history of gamma-ray telescopes, the SCT design is expected to boost CTA performance towards the theoretical limit of the technology.” |
The SCT’s complex dual-mirror optical system improves on the single-mirror designs traditionally used in gamma-ray telescopes by dramatically enhancing the optical quality of their focused light over a large region of the sky and by enabling the use of compact, highly-efficient photo-sensors in the telescope camera.
“Ultimately, the SCT is designed to improve CTA’s ability to detect very-high-energy gamma-ray sources, which may also be sources of neutrinos and gravitational waves,” said Prof. Vladimir Vassiliev, Principal Investigator, pSCT. “Once the SCT technology is demonstrated at FLWO, it is hoped that SCTs will become a part of at least one of the two CTA arrays, located in each of the northern and southern hemispheres.”
Above: Time lapse of pSCT mechanical structure construction
The CTA Observatory (CTAO) will consist of 118 telescopes split between a southern array in Paranal, Chile and a northern array on the island of La Palma, Spain. Three classes of telescopes (Small-, Medium- and Large-Sized Telescopes) will be used to detect gamma rays in the energy range 20 GeV to 300 TeV with about ten times increased sensitivity compared to any current observatory. Notable for providing improved gamma-ray angular resolution and its very-high-resolution camera (>11,000 pixels), the SCT is proposed for the medium-sized CTA telescopes, which are considered to be the “workhorses” of the arrays with 15 planned for the north site and 25 for the south site.
“The SCT and other telescopes at CTA will greatly improve upon current gamma-ray research being conducted at HAWC, H.E.S.S., MAGIC and VERITAS, the last of which is located at the Fred Lawrence Whipple Observatory,” said Dr. Wystan Benbow, Director, VERITAS. “Gamma-ray observatories like VERITAS have been operating for 12 to 16 years, and their many successes have brought very-high-energy gamma-ray astronomy into the mainstream, and have made many exciting discoveries. We hope CTA will supersede VERITAS around 2023, and it will be used to continue to build upon the 50 years of gamma-ray research at the Whipple Observatory and elsewhere.”
“I am very pleased to congratulate our colleagues that have conceived and realised such a promising prototype for the Medium-Sized Telescopes, a major component of the family of instruments that will characterise the CTA Observatory,” said Federico Ferrini, Managing Director of the CTAO.”
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CTA Prototype Telescope, the Schwarzschild-Couder Telescope,
Licia Verde, ICREA researcher at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), has been awarded the National Research Prize 2018. This distinction, granted by the Government of the Generalitat and the Catalan Foundation for Research and Innovation (FCRi) recognizes the researcher who has recently contributed significantly internationally to the advancement of a scientific discipline in any of its fields: human and social sciences, life sciences and health, engineering and technology and experimental sciences.
The jury has valued the work of Licia Verde for its pioneering findings on Universe and to contribute decisively to understand how matter and dark energy are distributed in the universe. Licia Verde is an ICREA researcher at the ICCUB since 2010 and leads the Cosmology and Large Scale Structure Group. Among other awards, she received a Starting Grant from the ERC in 2009 and the Gruber Prize for Cosmology in 2012. She is an expert in topics of theoretical cosmology, cosmic microwave background radiation, large-scale structure statistical applications and data analysis. On a large scale, galaxy clusters, statistical applications and data analysis. During her professional career, Verde has worked on the main cosmology projects of the last decade: 2dF Galaxy Redshift Survey (2dFGRS), Wilkinson Microwave Anisotropy Probe (WMAP) and Sloan Digital Sky Survey (SDSS).
The National Research Prize for Young Talent was by Marc Güell, a researcher at the Pompeu Fabra University (UPF); The National Award for Scientific Patronage has been awarded to the Pasqual Maragall Foundation, and the National Prize for the Public-Private Partnership in R & I at the Repsol-BSC Research Center.
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Licia Verde awarded the Premi Nacional de Recerca 2018
he Cherenkov Telescope Array Observatory (CTAO) Council and European Southern Observatory (ESO) have signed the final agreements needed for CTA’s southern hemisphere array to be hosted near ESO’s Paranal Observatory in Chile.
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) or National Commission for Scientific and Technological Research. With these three agreements in place, the CTAO will be able to begin construction on the southern site. The hosting agreement with the Instituto de Astrofísica de Canarias (IAC) is already in place to host CTA’snorther n hemisphere arrayat the Observatorio del Roque de los Muchachos in La Palma, Spain. Construction on both the northern and southern arrays is expected to begin in 2020.
Federico Ferrini, Managing Director of the Cherenkov Telescope Array Observatory (CTAO), met ESO’s Director General, Xavier Barcons at the Chilean Ministry of Foreign Affairs in Santiago. Together with ESO’s Director for Operations, Andreas Kaufer, they signed the agreement for the construction and operation of the CTA’s southern array at ESO’s Paranal-Armazones site in northern Chile. Preceding the signing of the two agreements on Wednesday, Ferrini met CONICYT’s Executive Director, Christian Nicolai Orellana on 17 December to sign the scientific collaboration agreement between the two parties.
CTA will be the next generation ground-based instrument in the detection of gamma rays, which are very high-energy electromagnetic radiation emitted by the hottest and most powerful objects in the Universe — such as supermassive black holes, supernovae and possibly remnants of the Big Bang. To provide access to the whole sky, the CTA Observatory will have two sites, with 19 telescopes in the northern hemisphere and 99 in the southern hemisphere.
CTA’s southern site is less than ten kilometres southeast of the location of the Very Large Telescope at ESO's Paranal Observatory in the Atacama Desert, and only 23 kilometres from the construction site of the upcoming Extremely Large Telescope. This is one of the driest and most isolated regions on Earth — an astronomical paradise. In addition to the ideal conditions for year-round observation, installing CTA at the Paranal Observatory brings the advantages of ESO’s expertise and infrastructure.
Current gamma-ray telescope arrays only consist of a handful of individual telescopes, but CTA — with its larger collecting area and wider sky coverage — will be the largest and most sensitive array of gamma-ray telescopes in the world, with unprecedented accuracy and 10 times more sensitive than existing instruments.
Although the Earth’s atmosphere prevents gamma rays from reaching the surface, CTA’s mirrors and high-speed cameras will capture the short-lived flashes of eerie blue Cherenkov radiation produced when gamma rays interact with the atmosphere. Detection of this Cherenkov light will allow the gamma ray to be traced back to its cosmic source.
The scientific scope of CTA is extremely broad: from understanding the role of relativistic cosmic particles to the search for dark matter. CTA will explore the extreme Universe, probing environments from the immediate neighbourhood of black holes to cosmic voids on the largest scales. It may even lead to brand new physics as it studies the nature of matter and forces beyond the Standard Model.
More than 1,400 scientists and engineers from 31 countries are engaged in the scientific and technical development of CTA. The Observatory will be constructed and operated by the CTAO ERIC, which is governed by member states and associate members from a growing number of countries.
Shareholders of CTAO gGmbH – the entity that is preparing for the CTAO ERIC – are representatives of ministries and funding agencies from Australia, Austria, Czech Republic, France, Germany, Italy, the Netherlands, Japan, Slovenia, South Africa, Spain, Switzerland and the United Kingdom [1].
Notes
[1] The Netherlands and South Africa attend as observers.
More Information
CTA is a global initiative to build the world’s largest and most sensitive high-energy gamma-ray observatory. More than 1,400 scientists and engineers from 31 countries across five continents (Armenia, Australia, Austria, Brazil, Bulgaria, Canada, Chile, Croatia, the Czech Republic, Finland, France, Germany, Greece, India, Ireland, Italy, Japan, Mexico, Namibia, the Netherlands, Norway, Poland, Slovenia, South Africa, Spain, Sweden, Switzerland, Thailand, the United Kingdom, the United States of America and Ukraine) and more than 200 research institutes are participating in the CTA project. CTA will be the foremost global observatory for very high-energy gamma-ray astronomy over the next decade and beyond and will be the first ground-based gamma-ray astronomy observatory open to the world-wide astronomical and particle physics communities.
CTA’s northern hemisphere site & the ICCUB
 Rendering Credit: Gabriel Pérez Diaz, IAC, SMM | CTA’s northern hemisphere site is located on the existing site of the Instituto de Astrofisica de Canarias’ (IAC’s) Observatorio del Roque de los Muchachos in Villa de Garafia on the island of La Palma. |
While the southern hemisphere array will span the entire energy range of CTA, covering gamma-ray energies from 20 GeV to more than 300 TeV, the northern hemisphere array will be more limited in size and will focus on the low- and mid-energy ranges from 20 GeV to 20 TeV. For this reason, the northern hemisphere site will not host any Small-Sized Telescopes, which are tuned to capture the highest-energy gamma rays. The plan is for the site to host four Large-Sized Telescopes to capture the low-energy sensitivity of CTA and 15 Medium-Sized Telescopes to cover CTA’s core energy range.
0n October 2018 was celebrated the inauguration of the first prototype Large-Sized Telescope (LST). The Institute of Cosmos Sciences (ICCUB) had an important participation in the technological development of the LST-1, contributing to the design of one of the signal amplification devices and to the definition of the scientific objectives of the project.
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Final Agreements Signed for CTA’s Southern Hemisphere Site i
The observatories are also publishing their first gravitational-wave events catalog
From September 12, 2015, to January 19, 2016, during the first LIGO observing run since undergoing upgrades in a program called Advanced LIGO, gravitational waves from three binary black hole mergers were detected. The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded a binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational wave events being reported now. The new events are known as GW170729, GW170809, GW170818 and GW170823 based on the dates on which they were detected.
The Virgo interferometer joined the two LIGO detectors on August 1, 2017, while LIGO was in its second observing run. Although the LIGO-Virgo three-detector network was operational for only three-and-a-half weeks, five events were observed in this period. Two events detected jointly by LIGO and Virgo, GW170814 and GW170817, have already been reported.
One of the new events, GW170818, detected by the global network formed by the LIGO and Virgo observatories, was precisely pinpointed in the sky. The sky position of the binary black holes, located about 2.5 billion light-years from Earth, was identified with a precision of 39 square degrees. That makes it the next best localized gravitational-wave source after the GW170817 neutron star merger.
The figure shows the localizations of the various gravitational-wave detections in the sky. The triple detections are labelled as HLV, from the initials of the three interferometers (LIGO-Hanford, LIGO-Livingston and Virgo) that observed the signals. The reduced areas of the triple events demonstrate the capabilities of the global gravitational-wave network.
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LIGO and Virgo collaborations announce four new gravitationa
Cosmology, gravitation, particle physics, atomic physics and nuclear physics are the topics to be treated in a disseminating way in the new portal of the Institute of Cosmos Sciences of the UB (ICCUB): ServiPartícules.
The aim is to help both the general public and the students and lecturers of primary and secondary education to broaden their knowledge on these fields of physics. To reach this, the portal aims to give more visibility to the amount of dissemination activities in which many members of the Institute of Cosmos Sciences are taking part, so that people can easily access to the materials they create.
To work as a good searching tool and to check resources, the content of the portal is categorized under areas and type of resource. According to the type, these are divided into three big areas: news, activities, and dissemination materials. The new website expands the former dissemination portal from the Experimental Group of Particle Physics of the UB Discovering Particle Physics with the LHC, and completes the astronomy portal ServiAstro, from ICCUB and the Department of Quantum Physics and Astrophysics.
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ICCUB launches the dissemination portal ServiPartícules
ICCUB member and ICREA Professor Roberto Emparan was recently interviewed by BBC Mundo journal, during his visit to Peruvian festival "Hay festival Arequipa", where he was invited to participate in several interviews and round tables with other researchers.
As he is specialized in quantum gravity, string theory and black holes, the interview focused in dicussing the main physics questions in this fields.
Read it if you want to know more about the main theories that have changed our understandin on how the universe is organised.
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Roberto Emparan interviewed by BBC