Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and H.E.S.S. analysis
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Published:2024-06
Issue:
Volume:686
Page:A308
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ISSN:0004-6361
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Container-title:Astronomy & Astrophysics
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language:
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Short-container-title:A&A
Author:
Aharonian F., Ait Benkhali F., Aschersleben J., Ashkar H., Backes M., Baktash A., Barbosa Martins V., Batzofin R., Becherini Y., Berge D., Bernlöhr K., Bi B., Böttcher M., Boisson C., Bolmont J., de Bony de Lavergne M., Borowska J., Bradascio F., Breuhaus M., Brose R., Brown A., Brun F., Bruno B., Bulik T., Burger-Scheidlin C., Bylund T., Caroff S., Casanova S., Cecil R., Celic J., Cerruti M., Chambery P., Chand T., Chandra S., Chen A., Chibueze J., Chibueze O., Cotter G., Cristofari P., Devin J., Djannati-Ataï A., Djuvsland J., Dmytriiev A., Einecke S., Ernenwein J.-P., Fegan S., Feijen K., Filipović M., Fontaine G., Füßling M., Funk S., Gabici S., Gallant Y. A., Giavitto G., Glawion D., Glicenstein J. F., Glombitza J., Goswami P., Grolleron G., Grondin M.-H., Haerer L., Hinton J. A., Hofmann W., Holch T. L., Holler M., Horns D., Jamrozy M., Jankowsky F., Joshi V., Kasai E., Katarzyński K., Khatoon R., Khélifi B., Kluźniak W., Komin Nu., Kosack K., Kostunin D., Kundu A., Lang R. G., Le Stum S., Leitl F., Lemière A., Lemoine-Goumard M., Lenain J.-P., Leuschner F., Luashvili A., Mackey J., Malyshev D., Malyshev D., Marandon V., Marinos P., Martí-Devesa G., Marx R., Mehta A., Meyer M.ORCID, Mitchell A., Moderski R., Mohrmann L.ORCID, Montanari A., Moulin E., Murach T., de Naurois M., Niemiec J., O’Brien P., Ohm S., Olivera-Nieto L., de Ona Wilhelmi E., Ostrowski M., Panny S., Panter M., Parsons R. D., Peron G., Prokhorov D. A., Pühlhofer G., Punch M., Quirrenbach A., Regeard M., Reichherzer P., Reimer A., Reimer O., Ren H., Renaud M., Reville B., Rieger F., Roellinghoff G., Rudak B., Sahakian V., Salzmann H., Sasaki M., Schüssler F., Schutte H. M., Shapopi J. N. S., Specovius A., Spencer S., Stawarz Ł., Steenkamp R., Steinmassl S., Steppa C., Streil K., Sushch I., Suzuki H., Takahashi T., Tanaka T., Terrier R., Tluczykont M., Tsuji N., Unbehaun T.ORCID, van Eldik C., Vecchi M., Veh J., Venter C., Vink J., Wach T., Wagner S. J., Wierzcholska A., Zacharias M., Zargaryan D., Zdziarski A. A., Zech A., Zouari S., Żywucka N., Harding A.
Abstract
The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy γ rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula’s γ-ray emission between 1 GeV and ∼100 TeV, that is, over five orders of magnitude in energy. Using the open-source software package GAMMAPY, we combined 11.4 yr of data from the Fermi Large Area Telescope and 80 h of High Energy Stereoscopic System (H.E.S.S.) data at the event level and provide a measurement of the spatial extension of the nebula and its energy spectrum. We find evidence for a shrinking of the nebula with increasing γ-ray energy. Furthermore, we fitted several phenomenological models to the measured data, finding that none of them can fully describe the spatial extension and the spectral energy distribution at the same time. Especially the extension measured at TeV energies appears too large when compared to the X-ray emission. Our measurements probe the structure of the magnetic field between the pulsar wind termination shock and the dust torus, and we conclude that the magnetic field strength decreases with increasing distance from the pulsar. We complement our study with a careful assessment of systematic uncertainties.
Funder
Science and Technology Facilities Council Irish Research Council Science Foundation Ireland Knut och Alice Wallenbergs Stiftelse South African Department of Science and Technology South African National Research Foundation University of Namibia National Commission on Research, Science and Technology Bundesministerium für Bildung, Wissenschaft und Forschung Austrian Science Fund Australian Research Council Japan Society for the Promotion of Science Universiteit van Amsterdam Science Committee of Armenia Bundesministerium für Bildung und Forschung Max-Planck-Gesellschaft Deutsche Forschungsgemeinschaft Helmholtz-Gemeinschaft Alexander von Humboldt-Stiftung Ministère de l'Enseignement Supérieur et de la Recherche Centre National de la Recherche Scientifique Commissariat à l'Énergie Atomique et aux Énergies Alternatives
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