Detection of very high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage

Aharonian F, Ait Benkhali F, Aschersleben J, Ashkar H, Barbosa Martins V, Batzofin R, Becherini Y, Berge D, Bernlöhr K, Böttcher M, Boisson C, Bolmont J, De Bony De Lavergne M, Bradascio F, Brose R, Brown A, Brun F, Bruno B, Burger-Scheidlin C, Casanova S, Celic J, Cerruti M, Chand T, Chandra S, Chen A, Chibueze J, Chibueze O, Collins T, Cotter G, Damascene Mbarubucyeye J, De Assis Scarpin J, Devin J, Djannati-Ataï A, Djuvsland J, Dmytriiev A, Egberts K, Einecke S, Ernenwein JP, Escañuela Nieves C, Feijen K, Filipovic M, Fontaine G, Funk S, Gabici S, Glicenstein JF, Grolleron G, Grondin MH, Haerer L, Heaß B, Hinton JA, Hofmann W, Holch TL, Holler M, Horns D, Huang Z, Jamrozy M, Jankowsky F, Jardin-Blicq A, Jung-Richardt I, Katarzyński K, Khatoon R, Khélifi B, Kluźniak W, Komin N, Kosack K, Kostunin D, Guedes Lang R, Le Stum S, Lemière A, Lemoine-Goumard M, Lenain JP, Luashvili A, Mackey J, Malyshev D, Marandon V, Marcowith A, Martí-Devesa G, Marx R, Mehta A, Mitchell A, Moderski R, Moghadam MO, Mohrmann L, Moulin E, De Naurois M, Niemiec J, Ohm S, Olivera-Nieto L, De Ona Wilhelmi E, Ostrowski M, Panny S, Panter M, Parsons RD, Pensec U, Pühlhofer G, Quirrenbach A, Ravikularaman S, Regeard M, Reimer A, Reimer O, Remy Q, Ren H, Reville B, Rieger F, Rowell G, Rudak B, Ruiz-Velasco E, Sabri K, Sahakian V, Salzmann H, Santangelo A, Sasaki M, Schäfer J, Schüssler F, Schutte HM, Shapopi JN, Spencer S, Stawarz Ł, Steenkamp R, Steinmassl S, Steppa C, Streil K, Tanaka T, Terrier R, Tluczykont M, Tsirou M, Tsuji N, van Eldik C, Vecchi M, Venter C, Wach T, Wagner SJ, Werner F, White R, Wierzcholska A, Zacharias M, Zdziarski AA, Zech A, Zywucka N (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Book Volume: 694

Article Number: A328

DOI: 10.1051/0004-6361/202453052

Abstract

The colliding-wind binary system η Carinae has been identified as a source of high-energy (HE, below ∼100 GeV) and very high-energy (VHE, above ∼100 GeV) gamma rays in the last decade, making it unique among these systems. With its eccentric 5.5-year-long orbit, the periastron passage, during which the stars are separated by only 1-2 au, is an intriguing time interval to probe particle acceleration processes within the system. In this work, we report on an extensive VHE observation campaign that for the first time covers the full periastron passage carried out with the High Energy Stereoscopic System (H.E.S.S.) in its 5-telescope configuration with upgraded cameras. The VHE gamma-ray emission from η Carinae was detected during the periastron passage with a steep spectrum with the spectral index Γ = 3.3 ± 0.2stat ± 0.1syst. Together with previous and follow-up observations, we derive a long-term light curve sampling one full orbit, showing hints of an increase in the VHE flux towards periastron, but no hint of variability during the passage itself. An analysis of contemporaneous Fermi-LAT data shows that the VHE spectrum represents a smooth continuation of the HE spectrum. From modelling the combined spectrum, we conclude that the gamma-ray emission region is located at distances of ∼10-20 au from the centre of mass of the system and that protons are accelerated up to energies of at least several tera-electronvolts inside the system in this phase.

Authors with CRIS profile

Involved external institutions

Dublin Institute for Advanced Studies (DIAS) Ireland (IE) Ruprecht-Karls-Universität Heidelberg Germany (DE) University of Groningen / Rijksuniversiteit Groningen Netherlands (NL) Laboratoire Leprince-Ringuet (LLR) France (FR) Deutsches Elektronen-Synchrotron DESY Germany (DE) Universität Potsdam Germany (DE) Université Paris Cité France (FR) Max-Planck-Institut für Kernphysik (MPIK) / Max Planck Institute for Nuclear Physics Germany (DE) Université de Bordeaux France (FR) Nicolaus Copernicus University (NCU) / Uniwersytet Mikołaja Kopernika w Toruniu (UMK) Poland (PL) Noordwes-Universiteit / North-West University South Africa (ZA) Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences Poland (PL) University of the Witwatersrand (WITS) South Africa (ZA) Université Paris-Saclay France (FR) Institut national de physique nucléaire et de physique des particules (IN2P3) France (FR) Sorbonne Université France (FR) Eberhard Karls Universität Tübingen Germany (DE) Institute of Research into the Fundamental Laws of the Universe / Institut de recherche sur les lois fondamentales de l'univers (IRFU) France (FR) University of Montpellier / Université Montpellier France (FR) Leopold-Franzens-Universität Innsbruck / University of Innsbruck Austria (AT) Institute of Nuclear Physics Polish Academy of Sciences / Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego Polskiej Akademii Nauk Poland (PL) Laboratoire Univers et Théories (LUTH) / Laboratory of the Universe and Theories France (FR) University of Oxford United Kingdom (GB) University of Adelaide Australia (AU) Yerevan Physics Institute (YerPhI) / Երևանի Ֆիզիկայի Ինստիտուտ Armenia (AM) Jagiellonian University / Uniwersytet Jagielloński (UJ) Poland (PL) University of Namibia (UNAM) Namibia (NA) Konan University / 甲南大学 Japan (JP) Universität Hamburg (UHH) Germany (DE) Riken Institute of Physical and Chemical Research / 理化学研究所 Japan (JP) Humboldt-Universität zu Berlin Germany (DE) University of Western Sydney Australia (AU)

How to cite

APA:

Aharonian, F., Ait Benkhali, F., Aschersleben, J., Ashkar, H., Barbosa Martins, V., Batzofin, R.,... Zywucka, N. (2025). Detection of very high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage. Astronomy & Astrophysics, 694. https://doi.org/10.1051/0004-6361/202453052

MLA:

Aharonian, F., et al. "Detection of very high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage." Astronomy & Astrophysics 694 (2025).

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