Towards open and reproducible multi-instrument analysis in gamma-ray astronomy

C. Nigro (1) , C. Deil (2) , R. Zanin (2) , T. Hassan (1) , J. King (3) , J. E. Ruiz (4) , L. Saha (5) , R. Terrier (6) , K. Brügge (7) , M. Nöthe (7) , R. Bird (8) , T. T. Y. Lin (9) , J. Aleksić (10) , C. Boisson (11) , J. L. Contreras (5) , A. Donath (2) , L. Jouvin (10) , N. Kelley-Hoskins (1) , B. Khelifi (6) , K. Kosack (12) , J. Rico (10) , A. Sinha (6)

1 DESY - Deutsches Elektronen-Synchrotron [Zeuthen]
2 MPIK - Max-Planck-Institut für Kernphysik
3 LSW - Landessternwarte Königstuhl [ZAH]
4 IAA - Instituto de Astrofísica de Andalucía
5 UCM - Universidad Complutense de Madrid = Complutense University of Madrid [Madrid]
6 APC (UMR_7164) - AstroParticule et Cosmologie
7 TU - Technische Universität Dortmund [Dortmund]
8 Department of Physics and Astronomy [UCLA, Los Angeles]
9 McGill University = Université McGill [Montréal, Canada]
10 IFAE - Institut de Física d’Altes Energies [Barcelone]
11 LUTH (UMR_8102) - Laboratoire Univers et Théories
12 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers

The analysis and combination of data from different gamma-ray instruments involves the use of collaboration proprietary software and case-by-case methods. The effort of defining a common data format for high-level data, namely event lists and instrument response functions (IRFs), has recently started for very-high-energy gamma-ray instruments, driven by the upcoming Cherenkov Telescope Array (CTA). In this work we implemented this prototypical data format for a small set of MAGIC, VERITAS, FACT, and H.E.S.S. Crab nebula observations, and we analyzed them with the open-source gammapy software package. By combining data from Fermi-LAT, and from four of the currently operating imaging atmospheric Cherenkov telescopes, we produced a joint maximum likelihood fit of the Crab nebula spectrum. Aspects of the statistical errors and the evaluation of systematic uncertainty are also commented upon, along with the release format of spectral measurements. The results presented in this work are obtained using open-access on-line assets that allow for a long-term reproducibility of the results.

Mots clés: methods: data analysis; gamma rays: general

Domaines: Astrophysique [astro-ph]

C. Nigro, C. Deil, R. Zanin, T. Hassan, J. King, et al.. Towards open and reproducible multi-instrument analysis in gamma-ray astronomy. Astronomy and Astrophysics - A&A, 2019, 625, pp.A10. ⟨10.1051/0004-6361/201834938⟩. ⟨cea-02129828⟩