Validation of standardized data formats and tools for ground-level particle-based gamma-ray observatories

¹ Physics Division, Los Alamos National Laboratory, Los Alamos, NM, USA
² Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de Mexico, México
³ Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico
⁴ Department of Physics, Pennsylvania State University, University Park, PA, USA
⁵ Department of Physics, Michigan Technological University, Houghton, MI, USA
⁶ Department of Physics, University of Maryland, College Park, MD, USA
⁷ Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, Mexico
⁸ Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
⁹ Instituto Nacional de Astrofísica, óptica y Electrónica, Puebla, Mexico
¹⁰ Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 IFJ-PAN, Krakow, Poland
¹¹ Centro de Investigación en Computación, Instituto Politécnico Nacional, México City, Mexico
¹² Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
¹³ Department of Physics, University of Wisconsin-Madison, Madison, WI, USA
¹⁴ Departamento de Física, Centro Universitario de Ciencias Exactase Ingenierias, Universidad de Guadalajara, Guadalajara, Mexico
¹⁵ Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias, Ave. Eugenio Garza Sada 2501, Monterrey, N.L., Mexico, 64849
¹⁶ Max-Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany
¹⁷ Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand
¹⁸ National Astronomical Research Institute of Thailand (Public Organization), Don Kaeo, MaeRim, Chiang Mai 50180, Thailand
¹⁹ Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
²⁰ Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
²¹ Universidad Politecnica de Pachuca, Pachuca, Hgo, Mexico
²² Space Science and Applications Group, Los Alamos National Laboratory, Los Alamos, NM, USA
²³ Dept of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
²⁴ Universidad Autónoma del Estado de Hidalgo, Pachuca, Mexico
²⁵ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
²⁶ University of Seoul, Seoul, Rep. of Korea
²⁷ Instituto de Física Corpuscular, CSIC, Universitat de València, E-46980 Paterna, Valencia, Spain
²⁸ Radboud Universiteit, Nijmegen, The Netherlands
²⁹ Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, USA
³⁰ Tsung-Dao Lee Institute and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, PR China
³¹ Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, DF, Mexico
³² Center for Astrophysics, Harvard and Smithsonian, Cambridge, MA, USA

Received: 11 March 2022
Accepted: 24 June 2022

Abstract

Context. Ground-based γ-ray astronomy is still a rather young field of research, with strong historical connections to particle physics. This is why most observations are conducted by experiments with proprietary data and analysis software, as is usual in the particle physics field. However, in recent years, this paradigm has been slowly shifting toward the development and use of open-source data formats and tools, driven by upcoming observatories such as the Cherenkov Telescope Array (CTA). In this context, a community-driven, shared data format (the gamma-astro-data-format, or GADF) and analysis tools such as Gammapy and ctools have been developed. So far, these efforts have been led by the Imaging Atmospheric Cherenkov Telescope community, leaving out other types of ground-based γ-ray instruments.

Aims. We aim to show that the data from ground particle arrays, such as the High-Altitude Water Cherenkov (HAWC) observatory, are also compatible with the GADF and can thus be fully analyzed using the related tools, in this case, Gammapy.

Methods. We reproduced several published HAWC results using Gammapy and data products compliant with GADF standard. We also illustrate the capabilities of the shared format and tools by producing a joint fit of the Crab spectrum including data from six different γ-ray experiments.

Results. We find excellent agreement with the reference results, a powerful confirmation of both the published results and the tools involved.

Conclusions. The data from particle detector arrays such as the HAWC observatory can be adapted to the GADF and thus analyzed with Gammapy. A common data format and shared analysis tools allow multi-instrument joint analysis and effective data sharing. To emphasize this, a sample of Crab nebula event lists is made public with this paper. Because of the complementary nature of pointing and wide-field instruments, this synergy will be distinctly beneficial for the joint scientific exploitation of future observatories such as the Southern Wide-field Gamma-ray Observatory and CTA.