During the week of October 4-8, the “Community Planning Meeting” (CPM2020) for the Snowmass 2021 took place. The aim was to developed the plans and the steps to take until the Community Summer Study (CSS) in July 2021. During the CSS a consensus on the key questions and opportunities of particle physics, enabling technologies and community engagement should be built and the content of the Snowmass Executive Summary should be formulated. The Snowmass21 process is leading to the final report, expected in October 2021. More information on the whole process is available here and from the Snowmass21 website.
A presentation on the European strategies for particle physics (2020), nuclear physics (2017), and astroparticle physics (2017), was delivered by Jorgen D’Hondt and was very well received. The Frontier-level workshops, including those of interest for APPEC (i.e. Theory, Neutrino, Cosmic, Instrumentation, Computational, Underground Facility and Infrastructure), have been organized since April 2020 and will continue through spring 2021. During CPM2020 the Frontiers received more than 1500 Letters of Interest which led to the organization of an impressive amount of parallel sessions during the second and third day on various topics of interest for APPEC, ranging from theoretical Dark Matter interpretations, and analysis/theory techniques for joint cosmological constraints, to future gravitational wave facilities.
The 10 frontiers and 80 topical groups will now develop the key questions and opportunities with the community members and converge on a series of white papers which will be used as inputs for the final report. An overview about the CMP2020 and the next steps for all frontiers is available in the October issue of Snowmass21 newsletter. The next milestone will be the Snowmass Mid-term Assessment during the 2021 APS April meeting.
Berrie Giebels, International Adviser representing APPEC
Update Jan ’21:
New Snowmass Timeline
Because of the COVID-19 pandemic, the Snowmass Report and the Community Summer Study meeting (CSS) will be delayed by one year until 2022. The overall schedule for the Snowmass process will be adjusted accordingly. After extensive consultation with the community and the frontier conveners/advisors, the Snowmass Steering Group recommends the following general guidelines for the implementation of the Snowmass delay:
High-level activities will be on hold until the end of June, 2021. These activities include Frontier-level and Topical Group-level workshops, All-conveners meetings, Advisory Group meetings and Newsletters.
Other Topical Group and cross-frontier activities should be either paused or reduced to a significantly lower level, proceeding only as necessary to ensure scientific continuity, meet essential programmatic needs, or maintain collaborative work with other units and communities.
No critical decisions will be made during the hiatus.
No individuals should feel obligated to participate in these activities.
Individual, collaborative and self-organized work can continue at the discretion of the individuals involved. All paused individual or group activities will continue to receive full consideration once the Snowmass process formally resumes.
With respect to the timelines:
White Paper submission to arXiv: no later than March 15, 2022. Late submissions and updates are likely not to be incorporated in the working group reports, but will be included in the Snowmass on-line archive documents.
Preliminary reports by the Topical Groups due: no later than May 31, 2022.
Preliminary reports by the Frontiers due: no later than June 30, 2022.
Snowmass Community Summer Study (CSS): July, 2022 at UW-Seattle.
All final reports by TGs and Frontiers due: no later than September 30, 2022.
Snowmass Book and the on-line archive documents due: October 31, 2022.
Additional remarks on the plans of the individual frontiers can be found in the Snowmass Newsletter of January 2021. The Snowmass Steering Group will continue to monitor the process.
The GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN, Italy, has reported its final results on the search for the neutrinoless double-beta (0νββ) decay of 76Ge in the December issue of Physical Review Letters [1]. No signal has been observed, but all goals of the final phase of the experiment have been achieved.
Germanium detetcors of the GERDA experiment. (Credits: GERDA)
The reported lower limit for the 0νββ half-life in 76Ge of 1.8×1026 yr agrees with the expected value for the sensitivity of the experiment; a more stringent value for the decay of any 0νββ isotope has never been measured before. Similarly, the reported background rate of 5.2×10-4 counts/(kg∙yr∙keV) in the signal region is second to none in the field, demonstrating not only the feasibility of a background-free experiment at high exposure but also providing the foundation for a next generation experiment with significantly higher sensitivity.
The hypothetical 0νββ decay is a process beyond the Standard Model of Particle Physics: two neutrons within a nucleus, here 76Ge, transform simultaneously into two protons and two electrons (‘beta particles’) without the common emission of two anti-neutrinos. Its detection would have profound implication for particle physics and cosmology: establishment of Lepton Number Violation and the Majorana nature of neutrinos, i.e. the identity of neutrinos and anti-neutrinos, access to the neutrino mass scale and an important clue for understanding why there is so much more matter than antimatter in the Universe.
A little more than 50 years ago, Lepton Number Violation had been, indeed, already the issue of the first 0νββ decay search with a 0.1 kg germanium detector chosen by a Milano group because of its outstanding intrinsic energy resolution [2] . Since then, the sensitivity has been increased by a factor of one million. Essential to this track record was the continuous increase of the mass of the detector which simultaneously is the source of the decay, accompanied by the incessant reduction of the background in the signal region: in particular, by running the experiments deep-underground for reducing the background from cosmic rays, and by increasing the 76Ge isotope fraction from 7.8% in the natural germanium detectors via enrichment up to almost 90%.
Circles: lower limit (90% C.L.) on the 0νββ decay halflife of 76Ge set by GERDA as a function of the exposure. Triangles: median expectation in the assumptionof no signal. (From [1])
The GERDA experiment has been operated since 2011 at the Laboratori Nazionali del Gran Sasso of INFN, Italy, below a rock over-burden of 3500 m water equivalent. In its final phase GERDA deployed 41 germanium detectors with a total mass of 44.2 kg and a 76Ge enrichment of 86-88%. Pioneering features are the key to progress: other than in the previous germanium experiments, the germanium detectors are operated without encapsulation in a cryostat of ultrapure liquid argon (LAr) immersed in an instrumented water tank as shield against photons, neutrons and muons. The LAr provides both cooling as well as shielding; furthermore, it helps to reduce the amount of mounting materials that, despite of careful screening, always exhibit a tiny rest of radioactive contaminants. For active shielding, the LAr is instrumented with light detectors which can indicate if a signal in the germanium detectors arises from radioactive background. Similar information can be gained from the time profile of the germanium detector signals. The GERDA collaboration has deployed detectors of novel design and developed new analysis tools in order to take full advantage of this background suppression technique.
The experience from GERDA has led to the expectation that further background reduction is in reach so that a background-free experiment with an even larger source strength respectively exposure becomes possible. The LEGEND collaboration [3] is aiming at increasing the sensitivity to the half-life of 0νββ decay up to 1028 yr. In a first phase, it will deploy a mass of 200 kg of enriched germanium detectors in the slightly modified infrastructure of GERDA with the start of data taking to be in 2021.
On November 4, 2020, the International Cosmic Day (ICD) took place for the 9th time. It focuses on the measurement of cosmic rays that surround us all the time, but are mostly unnoticed. During this day students should therefore explore these comsic rays and discover what secrets they bring with. The pandemic posed special challenges for this international event and at the same time offered the chance to explore new, innovative and unusual approaches. While in previous years all participants should measure the zenith dependancy of cosmic muons, this year both topic and format of the event was quite open. The only requirements was that the young people should learn about cosmic particles. This allowed to explore also new formats which can be used in the future.
Most of the activities during the International Cosmic Day took place online due to the pandemic. (Credits: DESY)
The type of activity was decided by the organizers on site – depending on what was possible. Some groups investigated the zenith angle distribution of muons with their own detectors or provided data, as known from previous years, and others met purely digitally. Colleagues in Italy streamed about four hours via Facebook, showed experiments and gave lectures. School classes or young people at home joined in. A a new form of cloud chamber workshop was tried out at DESY in Zeuthen. A teacher borrowed the cloud chamber sets for the classrom and together with the students they made their observations. A week later during a video meeting with the DESY team, scientists talked about their careers as researchers, gave insights into their daily tasks and showed pictures of their work on the experiments while the young people could asked a variety of questions: Starting from how to get a physics degree to technical and scientific questions about the observations with the cloud chamber. After this exchange, the young people summarized their day’s results in a page that will be included in the joint “conference booklet” which is prepared after the ICD with input from all participants.
In total, more than 4700 young people in 100 cities from 16 countries got involved with cosmic particles on this day. The exchange in the international video meeting calls was still the highlight for many young people, as the organizers reported. Offers such as an online quiz, a welcome message with greetings in the respective language of the participating countries or video meeting calls with up to five groups created a common framework and gave a sense of international flair.
Interview with Stavros Katsanevas about the Citizen Science project REINFORCE
The REINFORCE (Research Infrastructures FOR citizens in Europe) project aims to involve a broad public in the fascinating science of a Large Research Infrastructure. Through different citizen-science projects, REINFORCE aims to engage more than 100,000 citizens in making a genuine and valued contribution to managing the data avalanche. In this interview, we will learn more about the project from one of the project initiators, Stavros Katsanevas.
REINFORCE is a project on Citizen Science, what do you think are the benefits of Citizen Science, both for the participants as well as for the scientists from the Research Infrastructures?
REINFORCE (https://reinforceeu.eu/) has, as a main goal, the involvement of citizens in frontier science, accompanying the gravitational-wave and multi-messenger scientific revolutions in their progress, while strengthening the corresponding links with particle-physics searches (e.g. Dark Matter). It also addresses environmental science, through the natural and synergistic embedding of astroparticle infrastructures in the geosphere and, more generally, the environment. Furthermore, the multi-messenger understanding of the cosmos naturally brings forward multi-sensorial analyses of the data (e.g. extension to sound and acoustics) bringing in turn, inclusion and diversity; extending participation to the visually impaired, confined and senior citizens. It should be clear here, that the increase of the sensorial means of apprehension of reality, e.g. the acoustics, is not only pursued as a means to increase the inclusion of the visually impaired, but it is also considered as a way to increase our perception capability, multiplying the ways we separate signal from background. The same border crossing also happens between the cognitive and the affective and REINFORCE thus addresses issues of art and science. Last, but not least, we hope that the engagement with scientific practice brings forward elements of critical thinking, an urgent task in these times of media inflation and digital connectivity.
In this effort, REINFORCE faces the challenge of trying, in an implementation as a two-way process, to: avoid the “instrumentalisation” of the citizen, using them as a classifying machine; effectively mix human and algorithmic methods (e.g. machine learning); help them to properly separate the correlational from the causal; avoid simplistic “illustration” in both multi-sensorial and art and science representation; accompany citizens in the process, through initiatives involving presence, hangouts and collectively, for both experts and citizens, enhance the effort to distinguish signal from background noise.
The four demonstrators of the REINFORCE project (Credits: REINFORCE)
Which projects are part of REINFORCE? In addition, can you shortly explain the tasks the citizen scientist need to fulfil in these projects?
There are four projects, the gravitational-wave (GW) detector Virgo, at the European Gravitational Observatory, the high-energy neutrino-telescope, KM3Net, the ATLAS experiment at CERN and a muography project for geoscientific, archaeological and industrial infrastructure mapping. Regarding the specific tasks, let us start with Virgo. While the black-hole and neutron-star events detected follow specific General Relativity templates, used to identify the signal and also to extract the merger parameters, there are also transient events, “glitches” in the data, that are usually not related to astrophysical sources, but instead are caused by local disturbances, either technical or environmental, affecting the data quality and detection. So one of the tasks, for both GW experts and citizens, is to detect and classify glitches, that exhibit complex morphologies, to find their correlations and origin and remove them. A scientific discovery is not impossible, e.g. a supernova event would manifest itself as a glitch, and we have, from time to time, excitements of this sort. Machine Learning is also a promising tool to classify complex time-frequency patterns of glitches, and human input is required to train machine-learning models. An analogous task is performed in the KM3Net project, where citizen scientists help classify bioluminescence and bio-acoustic waveforms, forming the background for neutrino searches. In parallel, and changing point of view, these studies, address the issues of biodiversity of the deep sea. Pelagic and benthic bioluminescent organisms communicate through light. Cetaceans communicate through acoustic signalling, giving information on their sex, size and age. Here also, machine-learning algorithms can be of help. The two other projects concern tracking methods at the Atlas/LHC or cosmic rays, and the citizen scientist’s task is to go beyond the simple tracking algorithms, towards the identification of extra features, displaced vertices indices of new physics in LHC or extra hit signs of showering activity in the muography project. Here the citizens help to improve the search and reconstruction algorithms. In the muography case, again the relationship with environment, through the correlation of cosmic rays with nebulosity, atmospheric pressure etc. is an aspect of the task and can become a distributed activity around the schools of a region.
It is important to note here, that the above tasks profit from two important assets: a) the fact that they will be deployed in Zooniverse, currently the most visited citizen science platform in the world, whose initiator Chris Lintott and his group at Oxford University are partners in REINFORCE; b) the fact that data will be represented in both visual and acoustic forms, enhancing the classification and perception capabilities of both the expert scientists and the citizen scientists. In the second task, we are privileged to have the help of Wand Merced Diaz and Beatriz Garcia (of the sonoUno project) for the sonification of astronomical data. Wanda Merced Diaz, in particular, is a blind astronomer, who has for many years been leading a movement for the sonification of astronomical data, not only in the spirit of increasing inclusion, but also in the spirit of enhancing human perception potential. This last characteristic is special to the REINFORCE effort and distinguishes it for instance from the equally potent Gravity Spy project, authored by LIGO scientists, and which is already deployed in Zooniverse.
Sketch of the KM3NeT detector which is one of the large scale research infrastructures that join citizen science with the Deep Sea Hunters project. (Credits: KM3Net)
What events do you plan in the future?
We are currently finishing the beta version of our software, and we plan to have a full functioning environment for all four projects by the middle of 2021. The presentation of these citizen science environments will be inaugurated in summer 2021. Beyond the sprints and hangouts, that will necessarily accompany the participating citizens, we hope to also hold face-to-face meetings and we will continue to organise the series of workshops and “multiplying” events that have taken place this year and where the emphasis is on interactivity and feedback from the citizen scientists.
Furthermore, as I said above, for astroparticle physics, citizen science is naturally connected to a series of other themes: multi-messenger astrophysics, environmental and geoscience synergy, multi-sensorial development, art and science and critical thinking.
Regards multi-messenger physics, we are related to many other astroparticle physics efforts, that are also supported by other EU-funded projects (ESCAPE, ASTERICS) and, since our final deliverable is a roadmap for the field, we will try to coordinate with similar efforts towards this. APPEC is, of course, a perfect environment for this since the field has so many opportunities for exciting citizen science, through the plethora of open-data from gravitational waves to Vera Rubin/LSST maps. We will also organise, in the context of the EU-funded AHEAD2020 programme, workshops on multi-messenger physics, in 2021 and 2022; they will be an occasion to associate a citizen science element to the agenda.
This citizen-science roadmap should be in synergy with nearby science domains, particle and nuclear physics and astrophysics, eventually in the context of JENAS, but also, and in particular, geoscience and environment, with which we have been recently witnessing a convergence on many tools and concepts, from instrumentation to theory. This is even more so given that, in the first year of operation, we have been able to realise, through the many invitations we have received to present our programme (e.g. at the EU German Presidency event on Sustainable Development Goals through Citizen Science) that environmental and citizen-science themes will become a central framework, within which research and education opportunities will develop in the post-pandemic era.
A large number of activities will also be naturally centred on sonification. We are extremely happy that Wanda Merced Diaz will join the EGO staff in early 2021. Through her guidance, we are in contact with the UN Office for Outer Space Affairs (UNOOSA), as well as NASA and ESA experts on the sonification of astrophysical data. Furthermore, in the context of the sonification work, we have entered into contact with a series of “acousmatic” artists, and here also an art and science exhibition, along the spirit of “The Rhythm of Space”, which we organised in 2019, is under discussion. Last, but not least, we are in contact with Saul Perlmutter, whose “Big ideas Berkeley” critical-thinking course, “Sense and Sensibility in Science” has been an important inspiration for REINFORCE, in order to implement an equivalent European activity, using citizen-science data obtained above as first material.
Illustration of the so called glitches which should be recognized in the Gravitational Wave noise hunting project. (Credits: EGO)
It is statistically observed that the participation to Citizen Science activities decrease often exponentially. How do you think we can keep the citizen engaged and attract his/her long-term interest in activities?
We are lucky to have in REINFORCE, beyond the research actors (EGO, INFN (Italy), CNRS (France), University of Pisa (Italy), CONICET (Argentina), IASA (Greece)) a series of expert organisations, in education, engagement and citizen science (University of Oxford (UK), Open University (UK), Ellino-germaniki Agogi (Greece), ZSI – Center for Social Innovation (Austria), Lisbon Council for Economic Competitiveness and Social Renewal (Belgium), and the company Trust-IT) addressing the citizen-science engagement-strategy. This brings in parallel to the software development of the demonstrators, a large effort aimed at raising awareness and sustainability, in website building, webinars, communication material and social media.
In the context of this strategy definition, after an extensive study of bibliography and definition of criteria, a census (300 persons) was launched covering many countries and types of citizen scientist (from education to the general citizen) addressing key questions: Who are the potential citizen scientists that can be engaged in REINFORCE? How do we engage different target groups? Can we balance user inclusiveness and scientific productivity in the design and implementation of the REINFORCE demonstrators? What are the demonstrator design considerations to achieve such a balance? How can citizen motivation be sustained over time? What are the needs of different target groups? The first results of the survey show that a) respondents’ interest is high and that no significant changes are observed between demonstrators; b) motivations relevant to social standing and sharing with colleagues and social media do not seem as important as “helping to make discoveries” and “expecting to learn a lot about cutting edge science”; c) participants with prior experience in citizen science are (more) motivated by the opportunity to contribute to scientific research, by the opportunity to work with new data and feel more confident than the average to contribute in the project tasks; d) participants with strong scientific background display the same characteristics, with the addition that they “feel good to be involved in scientific research and are fascinated that they might make discoveries.”; e) “getting feedback”, “understanding the scientific impact of their work”, “receiving training” and using an “interface that is easy to manipulate” can be considered as the most important factors that can influence their sustained engagement. The results of the study are used to shape the project’s activities to design different, more targeted and appropriate engagement activities to successfully engage, train and retain them in the demonstrator project(s) for a longer period of time.
Do you also evaluate the impact of your Citizen Science projects?
Here we profit from the expert help of ZSI – the Center for Social Innovation (Austria), that has prepared a thorough plan, using state of the art methodology, based on a precise definition of inputs, outputs, outcomes and impact, to elaborate an impact-assessment strategy, including questionnaires, but also self-assessment, live interaction, pre- and post-involvement.
I would like to close on a series of more general thoughts. It is clear that after COVID-19 we are entering a new era, where communication and digital connectivity is becoming the definition of our social space-time, while in parallel Earthly and biological space-time-matter are at a critical point. We have also seen in the past months, examples of political/societal life around the world becoming more and more dependent on publicity-inspired mass-persuasion techniques, developing ambiguous relations to science and critical thinking. In parallel, researchers and teachers themselves suddenly became an ambiguous centre of attention. The content of academic research and education has also come under discussion. On the positive side, the pandemic brought teachers, digitally, in to the home. Families started to realise their role, the work of high-school teachers started to be recognised, breaking the ideologically dangerous “vendor-client” model of education. We academics should also admit that, in recent years, research and education have followed separate paths of specialisation, that have undoubtedly given great advances in science and technology, but also a sense of isolation to enthusiastic teachers attempting to communicate science in schools.
Once more, the proper embedding of humanity in the cosmos is in question, where the ancient notion of cosmos covers, as in antiquity, not only the Universe, but also the geosphere, society and the internal cosmos. A new synthesis of Research and Education, in the most general sense, is needed. I think that we are not alone in realising this. These facts were also remarked upon by the very inspiring article by Kip Thorne and Roger Blandford on “Post-pandemic science and education”, (https://aapt.scitation.org/doi/full/10.1119/10.0001390) where they even formulated a general call: “we scientists must now begin to think seriously about rebuilding our nation and society in the post-Covid era.“
In conclusion, there is plenty of interesting work in the citizen-science field for APPEC and for our newly-elected chair, Andreas Haungs, and General Secretary, Katarina Henjes-Kunst, to whom I seize the opportunity to wish a rich and productive mandate.
Stavros Katsanevas, currently Director of the European Gravitational Observatory (since 2018) and professor exceptional class at University of Paris, was born in 1953 in Athens. He has been assistant professor and professor at the Universities of Athens and Lyon, as well as CERN fellow and associate. He has worked in experiments on QCD, e+e-, supersymmetry and neutrinos at Fermilab (E537), CERN (ISR,PS180,DELPHI,OPERA) and the NESTOR high energy neutrino observatory. He has served as deputy director of the National Institute of Particle and Nuclear Physics (IN2P3) of CNRS (2002-2012); coordinator of the first ASPERA EU funded network of Astroparticle Physics (2006-2009); first chairman of APPEC (2012-2014); director of the Laboratory of Astroparticle Physics and Cosmology (APC) of IN2P3/CNRS-Paris Diderot-CEA-Observatoire de Paris (2014-2017) and co-director of the Astrophysics-Geophysics Laboratory of Excellence UnivEarths. He has also served as chair and co-chair of the European Gravitational Observatory Council (2002-2012); and chair of the Finance Board of the Auger Observatory (2011-2014).
Interview with Andreas Haungs and Katharina Henjes-Kunst
On December 9 at the General Assembly Meeting, a new Chair and a new General Secretary were appointed. The new Chairperson of the General Assembly (GA), which is the strategic and decision-making supervisory body, is Andreas Haungs who follows Teresa Montaruli. The new General Secretary Katharina Henjes-Kunst, following Job de Kleuver, now chairs the Joint Secretariat (JS), which is the executive body of APPEC. Both have long been closely engaged with APPEC and we are looking forward working with them in the next two years. In this interview they will tell us a bit about themselves and about their vision for the future of APPEC.
“APPEC can only be successful if there is close interaction between the three pillars GA, JS, and SAC. This is the recipe for APPEC’s success and I look forward to a functional and lively exchange between these three bodies.” Andreas Haungs, new APPEC Chair
What were your first thoughts and feelings when you found out about your election?
Andreas: The first thought was surprise at the result of the election, but this quickly turned into gratitude for the trust placed in me and joy at the exciting work ahead. The second thought was then directed to the excellent work of Teresa and Job in recent years with the desire and hope to carry on the very positive momentum for APPEC and continue to capitalize on it.
Katharina: When I heard that I was elected, I was very excited about the challenge of coordinating the working level of APPEC. I know that there are some big tasks ahead of us in APPEC in the next two years and I hope that with the strength of all APPEC partners we will successfully accomplish them. So I was happy and at the same time tense about the responsibility that is now coming my way.
Can you tell us a bit about yourself and your connection to astroparticle physics and to APPEC?
Andreas: As a trained particle physicist I joined the KASCADE high-energy cosmic-ray experiment in 1993 for my PhD. Since then I have been an astroparticle physicist with main and often leading activities in air-shower experiments like KASCADE-Grande, LOPES, the Pierre Auger Observatory and JEM-EUSO. The current basis of my research studies is the IceCube Observatory and since last year, I am involved in preparations for the Einstein Telescope. In all these experiments, my activities were directed always towards the whole life cycle of an experiment: From the development of suitable detectors to data analysis and making the scientific data sustainable and usable for the public. Beside the lead of a research group at KIT, I also can provide some experience in science management: I am manager of the KIT part of the Helmholtz research program “Matter and the Universe” and I serve as the elected co-chair of the German Committee for Astroparticle Physics. For APPEC I was active in the SAC between 2013 and 2017 as representative for cosmic rays. I am a member of the APPEC GA since 2018 representing KIT.
“I know that there are some big tasks ahead of us in APPEC in the next two years and I hope that with the strength of all APPEC partners we will successfully accomplish them.” Katharina Henjes-Kunst, new General Secretary
Katharina: In 2006 I started in the Technology Transfer Division of DESY for an FP 6 funded EU project (ERID-Watch1) to investigate the socio-economic impact of research infrastructures. Of course, in this tim I had contact to astroparticle physics research infrastructures, so I have visited MAGIC I in this time. Already in 2010 I became part of the EU funded ERA-NET ASPERA II for the coordination of European astroparticle physics and contributed significantly to topics like reports on research funding in astroparticle physics in Europe and several technology fora. This led to my last project, an EU project on the coordination of photosensor development in Europe (SENSE). I was coordinator of this project for three years, until it was successfully completed in 2019.
At the same time, I moved to the DESY astroparticle division and was part of a group who established a PhD school on Multimessenger astronomy (Helmholtz Weizmann Research School on Multimessenger Astronomy) and I am active in the coordination of the division, in this position I was again part of the APPEC JS during the last year.
Andreas, where do you see the most important challenge for astroparticle physics in the next years?
Andreas: Astroparticle physics is meanwhile an established field of research that encompasses a very broad spectrum of experimental and theoretical activities. In this sense spectrum refers not only to the content of the topics in astroparticle physics, but also to the variance in the size of the initiatives. Astroparticle physics ranges from small-scale experiments in laboratories to global large-scale observatories – addressing the entire range is important and necessary for overall success. Plans for large-scale global projects exist in all of our astroparticle physics domains (gamma ray and neutrino astronomy, gravitational wave research, or dark matter searches, to name a few examples) and it is a major challenge to guide and support the technological and structural developments, as well as the funding, towards these large-scale projects.
How do you see the role of APPEC, and especially the GA, to overcome this challenge?
I see the main task of APPEC on the control of the phase transition from small and medium sized experiments to large infrastructures across national borders. The selection of prioritized experiments for this transition must be scientifically sound and is the responsibility of the SAC. Only such a process ensures that the available resources are used optimally and that new possible resources can be made available. In particular, since there is no CERN, ESO, ESA or any other centre in European astroparticle physics that can perform these coordination tasks, coordination must be the responsibility of the APPEC GA.
What other topics would you like to address in the next two years?
Andreas: I see a focus of the upcoming term in the mid-term evaluation of the APPEC Roadmap with discussion of the results with the entire European astroparticle physics community and the culmination of this process, the targeted Town Meeting in Berlin in 2022. Furthermore, I see focal points of the activities in the continuation of the successful Technology Forum for synergetic work with the industry, as well as the interdisciplinary activities in the framework of JENAA. I also want to pay special attention to a structured global digitization of astroparticle physics, as well as a further strengthening of outreach, training and diversity in the research field.
Katharina, how can the Joint Secretariat support the General Assembly?
Katharina: Last year, a group of APPEC partners came together to reinvigorate the APPEC working level. Strengthening the working level must be the first step to fully support the activities that will be decided in the General Assembly. A regular consultation between Andreas Haungs and me is necessary to support the GA well. But I am sure that this will work out well – Andreas and I have already worked together very well on many projects before.
Beside this, what are the tasks you intend to work on with the Joint Secretariat?
Katharina: As already stated the first step is to reinvigorate the APPEC working level. Especially the year 2020 has shown us how important it is to be able to work in a distributed way – APPEC has established this early. I support the model of the distributed APPEC structure, with the so-called Functional Centers (FC) in different European countries. On the working level I would like to revive the Functional Centers with the support of the respective countries and establish a Joint Secretariat with more working power.
A central goal for me is to establish a successful and exciting Town Meeting in 2022 as exchange for the astroparticle physics community. The Town Meeting is intended to inform the community about the status of the implementation of the APPEC Roadmap and to provide space to discuss new developments. In the run-up to the Town Meeting I would like to encourage a Europe-wide discussion process to prepare the contents of the Town Meeting.
The support and guidance of European astroparticle physics communities in the set-up of new large infrastructures is an important task of APPEC. This is in particular relevant for the Einstein Telescope Project in the coming years which I want to specifically focus on in the coming years.
And of course, there are many, many more topics to support, just to mention all the activities which were already started with Teresa Montaruli and Job de Kleuver…
How important is the interplay and cooperation between the GA and the JS and also with third body of APPEC, the Scientific Advisory Committee?
Katharina: The APPEC SAC gives major input to APPEC – therefor the cooperation between all three APPEC bodies has to be strong. I was impressed by the report the SAC chair gave during the last GA meeting and I´m looking forward to work with the SAC on the APPEC Town Meeting and of course also all other topics.
Andreas: APPEC can only be successful if there is close interaction between the three pillars GA, JS, and SAC. This is the recipe for APPEC’s success and I look forward to a functional and lively exchange between these three bodies.
More broadly, what do you wish for the future of APPEC?
Katharina: I wish that APPEC will continue on the path to a vibrant federation of astroparticle physics in Europe and that it will be able to help shape the foundations for future developments in astroparticle physics over the next two years.
Andreas: The funding programs for astroparticle physics are very uneven throughout Europe and often embedded in larger research areas such as particle physics or astronomy. Especially for the large research infrastructures, an internationally operating network with coordination tasks is necessary. This is the broad field of action for APPEC. We need this strong body in Europe with high visibility and worldwide recognition.
Thanks to both of you and all the best for the coming two years.
And we want to especially thank the former Chair Teresa Montaruli and General Secretary Job de Kleuver for their work during the past years!
Teresa Montaruli and Job de Kleuver during an unexpected meeting at the Geneva airport.
On 9 December, the APPEC General Assembly came together for an online Meeting. The meeting was opened by a welcome from the APPEC Chair Teresa Montaruli and the General Secretary Job de Kleuver.
The first topic was on Neutrinoless Double Beta Decay, as follow-up of the sub-committee report, and how to develop a common strategy for future experiments, not only within Europe but also globally. Montaruli reported from a meeting with interested funding agencies from several European countries. But since coordination between North America and Europe seems to be necessary and a global approach is desired we aim for a European-North American Summit to achieve collectively a global investment strategy for the achievement of at least 2 projects for the 10-20 meV reach. A joint resolution document, signed by Funding Agencies, should be developed.
Then the approach towards a more sustainable APPEC was discussed. Supported by the current situation, in which we have all learned to work together online, the idea of a distributed workforce is to be implemented. The most active APPEC partners agreed to indicate dedicated people for such a distributed workforce, initially as in-kind contribution. The new General Secretary should then implement a more detailed division of tasks and lead the renewed APPEC Workforce and should also prepare a renewed funding model for discussion in the next year.
Screenshot during the APPEC General Assembly (Credits: APPEC)
After a short break the SAC Chair Sijbrand de Jong reported from the last SAC-meeting. one of the two main topics was on the Direct Dark Matter Detection sub-committee. An online Community feedback meeting to discuss the draft report with all stakeholders (in the wider APP community) is planned for 2 February 2021, further information is available here. After implementing the community feedback, a final report should be ready in March 2021 for approval by the General Assembly.
De Jong additionally reported on the other main topic, the status of the mid-term review of the APPEC Roadmap, which will serve as a basis for discussion at the planned APPEC Town Meeting.
This was a fitting lead in to the planning status of this very Town Meeting, which was the next agenda item. Since it was agreed that the Town Meeting should be held on site in Berlin, it was agreed to postpone it until early 2022. A more detailed planning for the Town Meeting preparations, including the option for input from national APP communities, will be discussed in a next General Assembly meeting.
The last topic before the lunch break was then the election of a new APPEC Chair and a new General Secretary (GS). Out of the three candidates available for the Chairperson, Andreas Haungs was elected as the new Chair for a fixed term of two years and Katharina Henjes-Kunst was appointed as the new GS for a first term of two years. The General Assembly thanked former Chair Teresa Montaruli and Co-Chair Christian Stegmann for their work in the last two years and highly appreciated the supportive work of former GS Job de Kleuver. The new Chair and GS were congratulated on their election and all look forward to continuing to work in good cooperation.
The next agenda item was a report from the Joint Secretary on the actions since the last meeting, including a status report on the APPEC Technology Forum (which is postponed until autumn 2021), on Communications and Outreach, common fund payments and the budget and meetings plan for 2020/2021.
Finally a report of joint ECFA-NuPECC-APPEC activities was given by Teresa Montaruli. Further information on these common activities are also available from this website http://nupecc.org/jenaa/ and were presented in an article in the last APPEC newsletter: Joint ECFA-NuPECC-APPEC activities
This agenda item was concluded by a report from the two chairs, Marek Lewitowicz from NuPECC and Jorgen d’Hondt from ECFA about their respective Consortia/ Committee.
As this was the last agenda item, Teresa Montaruli and Job de Kleuver closed the meeting with the best wishes for the coming holidays.
The CPPM team next to the junction box. Credits: KM3NeT
The three boats on site. Credits: KM3NeT
Another KM3NeT/ORCA detector deployment campaign in the Mediterranean was brought to a conclusion in October 2020. A second junction box (JB) has been successfully connected to the KM3NeT/ORCA seafloor network. The JB was deployed to within a metre of its nominal position at a depth of 2450 m.
The JB provides the power to the Detection Units (DUs) and distributes/collects the optical fibres used for the data transmission. The main electro-optic cable (MEOC) provides the input power on a single conductor at 3300 VAC which is transformed in the JB to 400 VAC to power the DUs. The power return is via the sea. The JB provides eight wet-mateable output connectors to which the DUs or Earth and Sea Sciences instrumentation (ESS) are connected via so called interlink cables. Four DUs are daisy chained to a single connector, so a single JB can connect up to 32 DUs. The JB was in fact ready since spring 2020 but due to COVID restrictions its connection was delayed until now.
The final configuration of the KM3NeT/ORCA site: N2 is the new junction box. Cable 2 will be the relocated ANTARES MEOC. MII, BJS, NSVT are earth and sea science instrumentation. Credits: KM3NeT
Deploying the junction box. Credits: KM3NeT
The campaign took place from the 16 Oct->24 Oct 2020. The operation was quite complex involving the coordination of three ships; i) The Raymond Croze from Orange Marine which managed the deployment of the junction box and the jointing of the main electro optical cables on the input and output of the junction box. ii) The Castor boat from Foselev Marine which managed the output main electro optical cable which, in a future operation, will be connected to a dedicated ESS junction box. iii) The Onyx boat from Foselev Marine which took care of the precision acoustic positioning of the junction box during its installation on the sea floor.
During the sea operation one end of the output MEOC was transferred from the Castor to the Raymond Croze for jointing (first time we have done that) and then the Castor lowered the output cable in synchronisation with the lowering of the JB. All in all, three joints were made; each joint requiring the splicing of up to 36 optical fibres and taking about 24 hours including encapsulation and X-ray control of the joint. We also had a weather standby of 36 hours.
The connection of the new junction box doubles the capacity of the ORCA seafloor network to connect DUs. In order to complete the ORCA sea floor network two more JBs will be needed; these will be connected to the MEOC currently being used by ANTARES telescope, once it is decommissioned and the extremity of the MEOC rerouted to the KM3NeT/ORCA site.
A short drone video of the deployment part of the sea operation can be viewed here.
The nuclear, particle and astroparticle physics communities, represented by the three committees/ consortia NuPECC, ECFA and APPEC want to join their forces not only to solve the questions on the smallest and the largest structures in nature but also to improve on diversity, working conditions and societal impact. The Deliberation document on the 2020 Update of the European Strategy for Particle Physics indicate the importance of mutual cooperation between the communities working on the science fields of relevance for APPEC and NuPECC with ECFA and includes the following recommendation, which is fully supported by APPEC: “There are many synergies between particle physics and other fields of research. Clear examples are nuclear and astroparticle physics, which address common fundamental questions and use common tools.”
The document further specifies this cooperation and concludes with a concrete proposal that encourages us to continue on our common path: “Links between accelerator-based particle physics and closely related fields such as astroparticle physics and nuclear physics should be strengthened through the exchange of expertise and technology in areas of common interest and mutual benefit. To further explore and enhance the synergies, a periodic joint seminar organised by APPEC, ECFA and NuPECC was recently established. For example, on the diverse topic of dark matter addressed with complementary experimental approaches, communication and results-sharing across communities is essential. ”
Joint ECFA-NuPECC-APPEC Seminars
The first Joint ECFA – NuPECC – APPEC Seminar (JENAS) was held at Orsay in 2019. There it was decided to have such meetings on a bi-yearly basis.
The chairs of APPEC, ECFA and NuPECC issued a call for venues for the second JENAS event, a 3 day meeting which will happen in the first half of 2022. The Joint Seminar is to inform our communities about each other’s scientific, technological and organizational challenges and opportunities. Two excellent proposals were received before the deadline at the end of September to host the event in Madrid and JINR. The choice of the organizing board of JENAS (ECFA: Manfred Krammer, Carlos Lacasta, Jorgen D’Hondt; NuPECC: Angela Bracco, Eberhard Widmann, Marek Lewitowitcz; APPEC: Teresa Montaruli, Stan Bentvelsen, and Marco Pallavicini) was difficult, given that the two proponents have very strong expertise in successfully hosting international events with the highest standards. It was decided that the venue will be Madrid, given the consideration that JINR is also proposed for a meeting in 2022 by ECFA.
Expression of Interest
A call for Expression of Interest (EoIs) was submitted by the Chairs (Teresa Montaruli, APPEC; Jorgen D’Hondt, ECFA; Marek Lewitowicz, NuPECC) of the three commitees/Consortia, with a request to identify the potential communities across the border of at least 2 of them and elaborate on the synergy topic and possible objectives.
Five EoIs were submitted and others will follow most probably. They are:
Storage Rings for the Search of Charged-Particle Electric Dipole Moments (EDM), by C. Carli, P. Lenisa, J. Pretz for the JEDI and CPEDM collaborations (https://indico.ph.tum.de/event/4482/overview)
A task force was formed to advise in the process of consolidating the scientific objectives and the organization, with the ultimate scope of making these initiatives sustainable over a long term these communities.
The respective EoI task force is composed by:
Francesca Calore and Uwe Oberlack for APPEC, Isabell Melzer-Pellmann and Claude Vallee for ECFA, Boris Sharkov for NuPECC
Tomek Bulik and Jo van den Brandt for APPEC, Peter Levai and Nick van Remortel for ECFA, Boris Sharkov and György Wolf for NuPECC
Jurgen Brunner and Elena Cuoco for APPEC, Marek Tasevsky and Mikko Voutilainen for ECFA, Franck Sabatié for NuPECC
Fiorenza Donato and Xin Wu for APPEC; Navin Alahari and György Wolf for NuPECC
Mike Seidel for ECFA, Hans Stroeher and Eberhard Widmann for NuPECC
A number of kick-off meetings, a global one and individual ones were organized by the Chairs. Excellent science have been illustrated in detail in each of them and synergy clearly highlighted.
For each EoI a topical follow-up meeting was organised by the coordinators together with the relevant members of the Task Force. The aim of these meetings was to develop a concrete roadmap for the future process.
Recently, two Test Science Projects (TSP), related to the science proposed by the two EoIs, were financed by the EOSC03 program for the project ESCAPE. One concerns relevant synergies, also highlighted by iDMEu on the dark matter searches with direct and indirect detection and colliders. The TSP has the aims of (1) understanding the nature of DM by collecting data, analysis and results from astronomy, particle and nuclear physics sources on a broad platform that will be ultimately hosted on the EOSC Portal; (2) exploiting synergies and complementarities across different communities, creating a unique link between DM as fundamental science question and the Open Science services needed to answer it. The other TSP is the Extreme Universe & Gravitational waves, with the aim to perform frontier multi-messenger science to understand extreme matter and particle processes in strongly curved space-time; to combine astronomy e-infrastructures and focus on data organization for different wavelengths/messengers and different types of extreme astrophysical transients (SNe, GRBs, FRBs, TDE,s), so that they can be easily gathered, analyzed and modeled. (See Giovanni Lamanna Talk at the ESFRI RIs – EOSC Workshop, Oct. 6-7)
Finally, a call for concrete proposals for financial support of EoIs activities to be submitted to the Committees was launched on October 14, 2020 with a deadline on November 23, 2020.
List of items that could be considered is:
1) Support the organization of gatherings across communities on the EoI topic, e.g. workshops, town meetings, platforms for continuous discussions.
2) Support the dissemination of the EoI topic, e.g. professional website, publications, outreach projects including city science projects.
3) Support to foster the cross-disciplinary research environments in a sustainable fashion.
Funding will be limited and may not always fulfil the wishes. Matching the requested funds with in-kind funds from the proponents themselves will be appreciated.
Diversity Charter
We recognise the importance of diversity as a motor to boost productivity and innovation, fight prejudice and discrimination and contribute to the improvement of social and economic standards.
The three organisations joined together to propose a Diversity Charter to be signed by research organisations, collaborations and conferences within the fields of Particle Physics, Nuclear Physics and Astroparticle Physics, who value diversity and commit to promote equal opportunities at all levels. A survey is a concrete proposed action. A request to adhere to the charter and provide data has been issued to some experiments. Any other experiment can apply to APPEC for joining the proposed Charter.
Recognition of individuals in big collaborations
The working group on recognition of individuals in big collaborations also made progress in the last month.
The key objectives of this working group are to create awareness, initiate discussions inside collaborations, exchange and discuss best practices among all three communities, and reflect on alternative or additional procedures,
The working group was installed in July 2019 in Ghent, It continues previous work by ECFA, which among other activities performed a community-wide survey in 2018. A second survey in 2020-2021 to monitor the progress on the topic will potentially be performed.
Initial meetings with the collaborations were held separately for the three communities in July. The APPEC representatives, Emmanuel Gangler and Karl-Heinz Kampert reported two lively and constructive meetings with the astroparticle experiments. A next round of meetings to collect feedback from the collaborations is planned for this autumn.
Teresa Montaruli, chair of the APPEC General Assembly
Up-to-date information on all efforts are available through the newly established JENAA website: http://www.nupecc.org/jenaa/
The Pierre Auger Collaboration has reported a measurement of the spectrum of cosmic-rays above 2.5 x 1018 eV made with unprecedented precision. A new spectral feature has been identified just above 1019 eV which is found to be independent of the direction from which the particles arrive. Taken together, the observations exclude the hypothesis that the highest-energy cosmic-rays come from a small number of nearby sources and that protons dominate in the particle beam.
One of the water-Cherenkov detectors (foreground) being filled with water. A fluorescence-detector station can be seen about 1500 m away on the hill in the background. An antenna at the Cherenkov detector is used to send data to another on the mast at the fluorescence station. Signals are then sent to the control room of the Observatory, 10 km away.
Credit: Pierre Auger Observatory
The existence of cosmic rays, dominantly the nuclei of atoms, with energies above 1019 eV has been known for over 60 years but limited data have allowed speculations on their origins to range freely. While it has long been thought that the sources of these particles must lie outside our galaxy, it is only recently, through the work of the Pierre Auger Collaboration, that this hypothesis has been confirmed experimentally1 with the demonstration of a modulation in right ascension of the arrival directions of events with energies above 8 x 1018 eV. Specifically, the first harmonic is 4.7 ± 0.8 % with the maximum of the effect in a direction nearly 180° from that of the galactic centre. The amplitude increases with energy. Our understanding of the birthplaces of these particles has now been further improved through measurements of the energy spectrum of ultra-high energy cosmic rays (UHECR) recently reported2 by the Collaboration and highlighted in APS Physics3. The results are derived from an unrivalled sample of over 215,000 events with energies above 2.5 x 1018 eV.
Properties of UHECRs are deduced by studying the cascades of electrons, photons and muons, usually called extensive air-showers, created by the impacts of high-energy nuclei on the atmosphere. At 1019 eV, where the flux is around 1 particle per km2 per year, a single nucleus generates ≈1010 particles spread over about 25 km2 at ground-level. At the Auger Observatory such showers are detected using an array of 1600 water-Cherenkov detectors deployed on a 1500 m triangular grid covering 3000 km2. Arrival directions are measured with a precision of ≈ 1°. The array is over-looked from four stations, each containing six telescopes that are used to detect fluorescence light produced by the excitation of nitrogen as the shower traverses the atmosphere. A calorimetric estimate of the energy for the ≈ 10% of events recorded on moonless nights is thus possible. In the picture a single Cherenkov detector and one of the fluorescence stations are shown.
The Auger measurements are unique as methods have been developed to enable the energy of each particle that initiates a cascade to be determined independent of assumptions about primary mass or of knowledge of the hadronic processes that control the cascade, many of which are at energies well-beyond that reached at the LHC. This is achieved by using the sub-set of events detected simultaneously with the fluorescence and water-Cherenkov detectors to provide a calibration. The energy resolution improves from ≈ 20% at 1 x 1018 eV to ≈ 7% one decade higher.
The energy density of UHECRs as a function of energy is shown in the plot below. The two well-established features, the ankle at 5 x 1018 eV and the steepening above 4 x 1019 eV, are clearly evident. In addition, a new feature at ≈ 1.3 x 1019 eV has been identified. A long-standing and popular framework to explain the observations has been that UHECRs are from sources distributed universally throughout the Universe that accelerate only protons. Both the ankle and the steepening features would then be explicable by energy losses of these protons through interactions with the photons of the cosmic microwave background. However, not only are our results on mass composition4 in strong tension with a pure proton composition around and above the ankle energy, but also the new feature, absent from the popular framework, rules out such a pure-proton paradigm. Further, the attributes of all three spectral features are found to be independent of the declination band from which events arrive. Thus, from this observation, the hypothesis that the new feature could stem from the distinctive spectrum of a local source that emits only protons and contributes significantly to the total intensity is also disfavored.
The energy density in cosmic rays as above 2.5 x 1018 eV. A new feature has been identified in the spectrum between the ankle, where the spectrum flattens at ≈ 5 x 1018 eV, and the place where it steepens sharply above ≈ 4 x 1019 eV. An illustrative comparison of estimates of the fluxes of different nuclei at the top of the atmosphere, deduced from the model discussed in the text, is indicated by the coloured lines: protons (red), helium (white), CNO group (green), Si (blue) and Fe (cyan).
Credit: APS/Alan Stonebraker; adapted from A. Aab et al. (Pierre Auger Collaboration), Phys. Rev. Lett. 125, 121106 (2020)
By contrast, our results better fit a scenario in which several nuclear components contribute to the total intensity and in which the electromagnetic fields permeate source environments where nuclei are accelerated to a maximum energy proportional to their charge. The best reproduction of data by simultaneously fitting the energy spectrum and our estimate of the mass composition is shown in the plot above. In this framework, the steepening results from the combination of the maximum energy of acceleration of the heaviest nuclei at the sources and their photodisintegration around 5×1019 eV when colliding the background photon fields permeating the extragalactic space (the GZK5 effect). The steepening at ≈ 1019 eV reflects, on the other hand, the interplay between the flux contributions of the helium and carbon-nitrogen-oxygen components injected at the source with their distinct cutoff energies, shaped by photodisintegration during the propagation. To make up the all-particle spectrum below the ankle energy, as well as to fit the composition data, an additional component is further required, the origin of which remaining to be uncovered.
Goats surround one of the water-Cherenkov detectors of the Pierre Auger Observatory in Argentina. The Andes are in the background.
Credit: Pierre Auger Observatory / Miguel Salvadores
Above 5×1018 eV, the energy content of UHECRs in every cubic Mpc inferred from our data is ≈ 5.6×1053 erg, corresponding to about 1/4th of a solar mass. To supply this energy content, the luminosity density that sources emitting continuously must inject into extragalactic space as UHECRs can be constrained to ≈ 6×1044 erg Mpc−3 yr−1 above 5×1018 eV at a redshift of zero. Classes of extragalactic sources that match such rates in the gamma-ray band include active galactic nuclei and starburst galaxies. The flux pattern from these objects also provides an indication of anisotropy in UHECR arrival directions6.
The Auger Collaboration has devised an upgrade of the extensive air-shower array with scintillators installed above the water-Cherenkov detectors. This enhancement will enable concomitant measurements of the electromagnetic and muonic components, the combination of which yields the principal mass-sensitive observable for such instruments. Obtaining more information on the composition of cosmic rays at the highest energies is crucial to pinning-down the origin of the observed flux features.
1 A. Aab et al, Science 357 (2017) 1266-1270 ; A. Aab et al, The Astrophysical Journal 868 (2018) 4 2 A. Aab et al, Physical Review Letters 125 (2020) 121106; Physical Review D 102 (2020) 062005 3 S. Razzaque, Physics 13 (2020) 145 4 A. Aab et al, Physical Review D 90 (2014) 122005; Physics Letters B 762 (2016) 288 5 K. Greisen, Physical Review Letters, 16 (1966) 748; G. T. Zatsepin and V. A. Kuzmin, JETP Letters 4 (1966) 6 A. Aab et al, The Astrophysical Journal Letters 853 (2018) L29
Interview about the Gravitational Wave GW190521, detected by Virgo and LIGO, with Giovanni Losurdo
On 2 September the Virgo and LIGO collaborations published their discovery of the most massive Black Hole ever measured with Gravitational Waves. This is another huge milestone in the field of Gravitational Wave observations. The scientists observed the merging of two Black Holes of 66 and 85 solar masses, which generated a final Black Hole of around 142 solar masses. The particularity of this measurement and its impact on our understanding and knowledge of Black Holes will be explained to us by Giovanni Losurdo, spokesperson of the Virgo collaboration.
First of all congratulations to this new finding! Can you explain, why this observation is so unique?
This graphic shows the masses of black holes detected through electromagnetic observations (purple), black holes measured by gravitational-wave observations (blue), neutron stars measured with electromagnetic observations (yellow), and neutron stars detected through gravitational waves (orange). GW190521 is highlighted in the middle of the graphic as the merger of two black holes that produced a remnant that is the most massive black hole observed yet in gravitational waves. (Credit: LIGO-Virgo/ Northwestern U. / F. Elavsky & A. Geller )
Thank you! So far we knew two black hole families: the stellar black holes, with masses up to a few tens of solar masses (MS) and supermassive black holes (millions to billions MS). For the first time we have observed a so-called Intermediate Mass Black Hole in the range 100-1000 MS. This observation might be helpful to understand the origin of supermassive black holes and thus contribute to unveil one of the mysteries of our cosmos. And (what a happy coincidence!) while doing this interview we get the news about the Nobel Prize in Physics awarded to Reinhard Genzel and Andrea Ghez for the discovery of Sagittarius A, the supermassive black hole at the center of the Milky Way, together with Roger Penrose for his theoretical contributions.
Not only the highest ever measured remnant Black Hole is special in this system but also the mass of one of the primary Black Holes. Can you tell us more about this?
Indeed, there was a black hole in the binary system which should not exist…And this is the second reason why this event is so special, which also makes it puzzling. A mass of 85 MS falls in the so-called pair instability gap, a very important phenomenon in determining the fate of massive stars. The core of such stars may become very hot, so hot that photons become energetic enough to produce electron-position pairs. They thus disappear and, consequently, the radiation pressure, which competes with gravity maintaining the core stable, is progressively weaker and the star collapses. In this kind of collapse, according to the stellar evolution theory, there is no way to form a black hole as big as 85 MS. So how did it form? In one of the papers published on GW190521we have studied possible formation mechanisms, but each of them requires conditions which are not very likely. In any case astrophysicists have to scratch their heads!
What are the astrophysical implications from this discovery?
A still image from a numerical simulation of two black holes that inspiral and merge, emitting gravitational waves. The black holes have large and nearly equal masses, with one only 3% more massive than the other. The simulated gravitational wave signal is consistent with the GW190521 observation made by the LIGO and Virgo. (Credit: N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration)
The LIGO and Virgo observations are unveiling the properties of binary system of stellar mass black holes. However, it is still an open question how binary black holes form and evolve; if they directly come from the evolution of an isolated binary systems of massive stars or if they are formed in dense environment, such as star clusters due to dynamical interactions. The properties of GW190521 signal lay the foundation for understanding its origin. The most plausible scenarios of formation of the two massive blackholes giving birth to the intermediate mass black hole are via multiple stellar coalescences, or via hierarchical mergers of lower-mass black holes in star clusters or in active galactic nuclei. The dynamical scenario is also supported by the mild evidence for precession found in the gravitational-wave signal.
Does this have any new implication on what we know on Dark Matter and Dark Energy?
Investigating the cosmos through gravitational waves may shed light on the 95% of the universe which we do not know yet.
For instance, the collapse of large overdensities in the early Universe might have directly formed so-called primordial black holes. Such black holes did not originate from stars, they did exist well before the stars. They are extremely interesting objects since their existence, if proved, could account for a fraction of the dark matter. In principle, it is possible that the binary components of GW190521 have a primordial origin, though this scenario is disfavored by the large spin of the primary black hole.
Moreover, detecting compact binary coalescences up to cosmological distances through gravitational waves provide an absolute distance scale measurement. The relation among gravitational wave distances and redshift carry the signature of the dark energy. Gravitational-wave detectors of 3rd generation, such as Einstein Telescope, will observe a larger redshift range ideal to investigate the nature of the dark energy and modifications of gravity on cosmological scales.
Do you expect to see more Black Hole mergers with these high masses?
Aerial view of the Virgo experiment. (Credits:Virgo Collaboration/EGO)
Virgo and LIGO are now being upgraded in order to increase the volume of universe they can explore and thus the event rate. In fact, we alternate observing runs to periods when we work on enhancing the sensitivity of the detectors. Moreover, the KAGRA detector will join the network in the next observing run starting in 2022. As the world wide gravitational wave network becomes more sensitive the event rate increases. And so we expect that, in the next run, we might observe more events of this kind together with new, unexpected ones.
Events with high mass occur at lower frequencies – where LIGO and Virgo are less sensitive – do you expect to be still able to measure even higher masses?
In principle as we improve the sensitivities of the detector we might be able to see events with mass even larger than GW190521. However, the real breakthrough towards higher masses will happen with Einstein Telescope, the third generation European project aiming to widen the Virgo bandwidth down to 1 Hz. Furthermore, ET will explore all the observable Universe increasing the probability to detect the merger of intermediate massive black-holes.
Giovanni Losurdo is a Research Director of the National Institute of Nuclear Physics (INFN). He has worked on the Virgo experiment since its early years, in the 1990s. From 2009 to 2017 he has been the Project Leader of Advanced Virgo, the interferometer enhancement program that made it possible, in August 2017, to contribute to the observation of the gravitational waves emitted in the merger of two neutron stars, an epochal discovery that initiated a totally new way of observing the cosmos: multi-messenger astronomy. He is now serving as Spokesperson of the Virgo Collaboration.
He won the Galilei Prize for Science and the Tartufari Prize for Physics and Chemistry from the Accademia dei Lincei. He was awarded by President Mattarella with the honor of “Commendatore dell’Ordine al Merito della Repubblica Italiana”. Since 2019 he is a member of the Accademia Nazionale dei Lincei.
During the week of October 4-8, the “Community Planning Meeting” (CPM2020) for the Snowmass 2021 took place. The aim was to developed the plans and the steps to take until the Community Summer Study (CSS) in July 2021. During the CSS a consensus on the key questions and opportunities of particle physics, enabling technologies and community engagement should be built and the content of the Snowmass Executive Summary should be formulated. The Snowmass21 process is leading to the final report, expected in October 2021. More information on the whole process is available here and from the Snowmass21 website.
On November 4, 2020, the 
The nuclear, particle and astroparticle physics communities, represented by the three committees/ consortia NuPECC, ECFA and APPEC want to join their forces not only to solve the questions on the smallest and the largest structures in nature but also to improve on diversity, working conditions and societal impact. The 
