CosmoVerseSchool@Sofia (25-31 May 2026)
Our understanding of the Universe is at a turning point with the predictions of the standard model of cosmology (or concordance model), and the observations from different surveys showing tensions in several key areas. The disagreement is expressed in the value of cosmic expansion as well as in the growth of large-scale structure in the Universe. New cosmological surveys, many of which are European, may expose tension in additional areas of the concordance model. The question of cosmological tensions can be confronted in a number of ways. Firstly, survey data needs to be further analyzed for potential systematic uncertainties or biases. It would also be interesting to explore predictions from possible combined survey data, which is something survey collaborations cannot normally explore. Secondly, there have been numerous advances in approaches to data analysis and statistical approaches, some of which provide less dependence on cosmological models to make cosmological parameter estimates. Lastly, there are a plethora of new proposals from fundamental physics which range from novel neutrino physics to dark energy proposals (and others) which may contribute to a solution to the cosmological tensions problem. These represent the three research themes through which cosmological tensions will either be alleviated or resolved.
The main aim of CosmoVerse is to establish a synergy between these research areas and foster a sustainable network based on interdisciplinary research in order to confront the growing challenges of tensions in cosmological survey data. CosmoVerse will take a harmonized approach involving all key communities.
CosmoVerseSchool@Sofia 2026 is the second school by the CosmoVerse COST Action and centers on the interface of observational measurements and data analysis of these data sets. Within CosmoVerse, this features the intersection of Working Groups 1 (Observational Cosmology and systematics) and 2 (Data Analysis in Cosmology) (see here for more information). The School will cover lectures and training in analyzing observational data sets in the context of cosmological parameter estimates. This is connected to the CosmoVerse Data Challenge.
Venue
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria
Lecturers
Siyang Li (University of California, Berkeley, USA)
Yukei Murakami (Johns Hopkins University, USA)
Kayla Owens (University of Chicago, USA)
Louise Breuval (Space Telescope Science Institute, Baltimore, USA)
Teresa Sicignano (Scuola Superiore Meridionale – INAF-OACN, Italy)
Important dates
1 November 2025: Registration and abstract submission opens
1 February 2026: Registration and abstract submission deadline
25-31 May 2026: School days
27 May 2026: Conference Dinner
28 May 2026: Public Lecture
SOC
Siyang Li (University of California, Berkeley, USA)
Jackson Levi Said (University of Malta, MT)
Eleonora Di Valentino (Sheffield University, UK)
Noemi Frusciante (UNINA, IT)
Agnieszka Pollo (National Center for Nuclear Research, PL)
Marika Asgari (Newcastle University, UK)
LOC
Denitsa Staicova (Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences)
Lilia Anguelova (Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences)
Michail Stoilov(Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences)
Petar Danev(Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences)
Hristo Tonchev(Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences)
Funding
The School has no registration fees for all participants. The CosmoVerse COST Action will provide funding (travel & subsistence) to a number of students in attendance. However, if alternative funding is available, we ask that students take this into consideration.
Getting to Sofia
Sofia, the capital of Bulgaria, is easily accessible by air, rail, and bus.
By air:
Sofia International Airport “Vasil Levski” (SOF) is located about 10 km from the city center. It has direct connections to most major European cities. The city center can be reached in about 20–30 minutes by taxi, metro, or bus.
Metro: Line M4 connects Terminal 2 directly to the city center (about 30 min, ticket €0.80 / 1.60 BGN) (map).
Bus: Bus 84 and 184 connect both terminals to central Sofia (ticket €0.80 / 1.60 BGN) (map).
Taxi: The official taxi operator OK Supertrans can be found outside the arrivals area (approx. €10–15 / 20–30 BGN to the center).
By train or bus:
Sofia Central Railway Station and the nearby Central Bus Station offer international and domestic connections. Both are directly linked to the city’s metro and public transport network.
Public transport:
Sofia’s public transport includes metro, trams, and buses. Single-ride tickets cost about €0.80 (1.60 BGN). Daily and multiday passes are also available.
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