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Principia Program on Multi-Messenger Astrophysics


Recent detections of astrophysical events in non-electromagnetic channels have opened up new areas of research involving the exploration of the cosmos using multiple messengers (MM). Astronomers have always used different wavelengths, from radio to gamma rays, in order to probe physical phenomena on small and on large scales, as well as low and high energies. However, in the past few years we also have gained access to a variety of channels that can be traced to the same objects or events: high-energy cosmic rays, neutrinos, as well as gravitational waves. Each one of these messengers provide different windows on black holes (BHs), neutron stars (NSs), quasars, blazars, supernovae and other sources, and the complementarity of those observations is starting to have a deep impact on physics and astronomy.


Our goal is to foster this fast-growing area of research in Brazil by bringing a selected group of specialists to the "Principia Program on Multi-Messenger Astrophysics”. This event will start by mapping out the opportunities for research and for new discoveries in astrophysics, cosmology and fundamental physics. The Program will also identify how the Brazilian physics and astronomy communities can better prepare for the new fields of research that will open up as a result of the growing number and quality of events with MM observations. Another important aspect is the new generation of experiments and instruments that will play a role in MM astrophysics over the next decade: which of the existing projects have a higher chance of impact, and of those, in which would Brazilian researchers be able to play a significant role? Finally, what are the capabilities of local industries to provide technological support for these projects, in terms of instrumentation or components that can be locally sourced?





MM Astrophysics will have a profound impact on basic Science, with huge potential for disruptive discoveries. As we prepare for the next generations of experiments, instruments and detectors, it is critical to identify which of those projects are better placed to take advantage of the complementarity between these different signals.


While some observations promote a gradual advancement of our understanding of the physical world, other observations are capable of quantum leaps, i.e., giant steps that can rule out entire classes of models at a stroke. One good example is the near coincidence of the signals from GW170817: the difference of at most a couple of seconds between the signals can be immediately compared with the time it took those signals to reach Earth from the galaxy NGC 4993: more than 100 million years. This observation alone enabled us to rule out entire classes of models that extend Einstein's theory of General Relativity.


Although MM Astrophysics is a rapidly growing field, most established researchers have built their careers and refined their expertise by focusing on one of the four main "messengers": photons, neutrinos, cosmic rays and gravitational waves. There are a few exceptions to this rule:

  • Experts on compact objects often study how those systems emit signals in multiple messengers;

  • Researchers working on dark matter detection often study how interactions or annihilations can generate signals in different channels such as neutrinos, gamma rays and/or cosmic rays;

  • Cosmic ray experts have always counted on high-energy photons to complement the observations of atmospheric showers; and

  • Neutrino physicists have long understood that some cataclysmic events, such as supernovae, radiate huge amounts of energy in both light (photons) and neutrinos.

Recently, the interplay between different messengers has strengthened the complementarity between gravitational wave astronomy and UV/optical/infrared astronomy, in particular relating to NS-NS/BH-NS mergers. Understanding new possibilities for MM observations can expand observations and the theories behind them. Investigation of MM physics will certainly enrich both astronomy and astroparticle physics research. Pursuing projects that explore the complementarity of different messengers is one of the key paths to improve both fields in the near future.


We now have an opportunity to foster the development of this area in Brazil and Latin America. Our goal with the Principia Program in Multi-Messenger Astrophysics is to:

  • Identify what are the main scientific problems that can be tackled using MM observations;

  • Develop strategies to facilitate the organic growth of a local group of researchers who will work in those fields;

  • Determine which new experiments, observatories and instruments have the greatest potential for MM science; and

  • Strengthen contacts with local industries that can be tapped in order to develop new technologies and to build parts for these new instruments.


Preliminary Schedule of the Principia Program on MM Astrophysics


The Principia Program will run over four (4) weeks, from May 22nd to June 16th, 2023, with more emphasis on the first week (May 22-26) and the fourth and final week (June 12-16). We will also hold social events interspersed with the main activities of the Program.


  • Week #1: May 22nd - May 26th

Welcome and general guidelines; short presentations with main challenges & opportunities of MM Astrophysics over the next 10 years; survey of MM Astrophysics activity around the world (theory & experiments); focus groups on different messengers and their interfaces; community day (May 24th: contributed talks from local researchers); assessment of strengths and weaknesses of local groups; discussion about strategies to build up stronger MMA communities and networks in Brazil & Latin America; summary of main conclusions from 1st week and first rough draft of a White Paper for the Brazilian community & funding agencies.

  • Week #2: May 29th - June 2nd

The Principia Program will run in parallel with the Advanced School. The Program will continue with focus groups on the different interfaces of MM Astrophysics and discussions between participants of the Program and lecturers of the School; we will also review discussions and results of the previous week with new participants; preparation of the draft of the White Paper will continue.

  • Week #3: June 4th - June 7th

The Principia Program will continue in parallel with the Advanced School. At this point we will have converged on a smaller set of theoretical challenges and new instruments, which will be further discussed between participants of the Program and lecturers of the School; during this week we will also have a focus group on the main new experiments that are worth investing in the future, and the prospects for participation in theoretical research as well as instrumentation.

  • Week #4: June 12th - June 16th

The final week of the Program will start with a summary of the main findings of previous weeks. The White Paper should now have taken shape, with a more clear definition of the scientific challenges and likely fields with potential for disruptive advances, and possible strategies to foster a new generation of researchers in MM Astrophysics; during this week we will also host an Industry Day, with visits from representatives of local industries and engineering firms that are potential partners for the development or construction of instrumentation for the next generation of MM experiments and observatories; the final days of the Principia Program will be dedicated to finishing the draft of the White Paper.

Local Organizing Committee:

L. Raul Abramo (Coordinator; Instituto de Física, Universidade de São Paulo)

Ivone Albuquerque (Instituto de Física, Universidade de São Paulo)

Rita de Cássia dos Anjos (Departamento de Engenharia e Ciências Exatas, Universidade Federal do Paraná)

Enrico Bertuzzo (Instituto de Física, Universidade de São Paulo)

Rodrigo Nemmen (Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo)

Orlando L. G. Peres (Instituto de Física Gleb Wataghin, Unicamp)

Edivaldo M. Santos (Instituto de Física, Universidade de São Paulo)

L. Vitor de Souza (Instituto de Física de São Carlos, Universidade de São Paulo)

Riccardo Sturani (Instituto de Física Teórica, UNESP)

For further enquiries about this event, please contact

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