H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883

Aharonian F, Benkhali FA, Aschersleben J, Ashkar H, Backes M, Martins VB, Batzofin R, Becherini Y, Berge D, Bernlöhr K, Bottcher M, Boisson C, Bolmont J, de Bony de Lavergne M, Borowska J, Bouyahiaoui M, Brose R, Brown A, Brun F, Bruno B, Bulik T, Burger-Scheidlin C, Caroff S, Casanova S, Celic J, Cerruti M, Chand T, Chandra S, Chen A, Chibueze J, Chibueze O, Cotter G, Mbarubucyeye JD, Devin J, Djuvsland J, Dmytriiev A, Egberts K, Einecke S, Ernenwein JP, Fontaine G, Funk S, Gabici S, Gallant YA, Glawion D, Glicenstein JF, Goswami P, Grolleron G, Haerer L, Heb B, Hofmann W, Holch TL, Holler M, Huang Z, Jamrozy M, Jankowsky F, Joshi V, Jung-Richardt I, Kasai E, Katarzyński K, Khangulyan D, Khatoon R, Khélifi B, Kluźniak W, Komin NU, Kosack K, Kostunin D, Kundu A, Guedes Lang R, Le Stum S, Leitl F, Lemiere A, Lemoine-Goumard M, Lenain JP, Leuschner F, Mackey J, Malyshev D, Marti-Devesa G, Marx R, Mehta A, Meintjes PJ, Mitchell A, Moderski R, Mohrmann L, Montanari A, Moulin E, Murach T, de Naurois M, Niemiec J, Ohm S, de Ona Wilhelmi E, Ostrowski M, Panny S, Panter M, Parsons RD, Pensec U, Peron G, Prokhorov DA, Pühlhofer G, Punch M, Quirrenbach A, Regeard M, Reimer A, Reimer O, Reis I, Ren H, Rieger F, Rudak B, Ruiz-Velasco E, Sahakian V, Salzmann H, Santangelo A, Sasaki M, Schäfer J, Schussler F, Schutte HM, Shapopi JN, Spencer S, Stawarz L, Steenkamp R, Steinmassl S, Steppa C, Streil K, Sushch I, Takahashi T, Tanaka T, Taylor AM, Terrier R, Thorpe-Morgan C, Tluczykont M, Unbehaun T, van Eldik C, van Soelen B, Vecchi M, Venter C, Vink J, Wach T, Wagner SJ, Werner F, Wierzcholska A, Zacharias M, Zdziarski AA, Zech A, Zywucka N (2024)

Publication Language: English

Publication Type: Journal article

Publication year: 2024

Journal

Book Volume: 687

Article Number: A219

DOI: 10.1051/0004-6361/202449612

Abstract

PSR B1259–63/LS 2883 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 yr period, around an O9.5Ve star (LS 2883). At orbital phases close to periastron passages, the system radiates bright and variable non-thermal emission, for which the temporal and spectral properties of this emission are, for now, poorly understood. In this regard, very high-energy (VHE) emission is especially useful to study and constrain radiation processes and particle acceleration in the system. We report on an extensive VHE observation campaign conducted with the High Energy Stereoscopic System, comprised of approximately 100 h of data taken over five months, from tp − 24 days to tp + 127 days around the system’s 2021 periastron passage (where tp is the time of periastron). We also present the timing and spectral analyses of the source. The VHE light curve in 2021 is consistent overall with the stacked light curve of all previous observations. Within the light curve, we report a VHE maximum at times coincident with the third X-ray peak first detected in the 2021 X-ray light curve. In the light curve – although sparsely sampled in this time period – we see no VHE enhancement during the second disc crossing. In addition, we see no correspondence to the 2021 GeV flare in the VHE light curve. The VHE spectrum obtained from the analysis of the 2021 dataset is best described by a power law of spectral index Γ = 2.65±0.04stat ±0.04sys, a value consistent with the spectral index obtained from the analysis of data collected with H.E.S.S. during the previous observations of the source. We report spectral variability with a difference of ∆Γ = 0.56 ± 0.18stat ± 0.10sys at 95% confidence intervals, between sub-periods of the 2021 dataset. We also detail our investigation into X-ray/TeV and GeV/TeV flux correlations in the 2021 periastron passage. We find a linear correlation between contemporaneous flux values of X-ray and TeV datasets, detected mainly after tp + 25 days, suggesting a change in the available energy for non-thermal radiation processes. We detect no significant correlation between GeV and TeV flux points, within the uncertainties of the measurements, from ∼tp − 23 days to ∼tp + 126 days. This suggests that the GeV and TeV emission originate from different electron populations.

Authors with CRIS profile

Involved external institutions

Dublin Institute for Advanced Studies (DIAS) Ireland (IE) University of Groningen / Rijksuniversiteit Groningen Netherlands (NL) Laboratoire Leprince-Ringuet (LLR) France (FR) University of Namibia (UNAM) Namibia (NA) Deutsches Elektronen-Synchrotron DESY Germany (DE) Max-Planck-Institut für Kernphysik (MPIK) / Max Planck Institute for Nuclear Physics Germany (DE) Noordwes-Universiteit / North-West University South Africa (ZA) Laboratoire Univers et Théories (LUTH) / Laboratory of the Universe and Theories France (FR) Sorbonne Université France (FR) Leopold-Franzens-Universität Innsbruck / University of Innsbruck Austria (AT) Ruprecht-Karls-Universität Heidelberg 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) Institute of Nuclear Physics Polish Academy of Sciences / Instytut Fizyki Jądrowej im. Henryka Niewodniczańskiego Polskiej Akademii Nauk Poland (PL) Jagiellonian University / Uniwersytet Jagielloński (UJ) Poland (PL) Universität Potsdam Germany (DE) University of Tokyo Japan (JP) Konan University / 甲南大学 Japan (JP) Université Paris-Sud France (FR) Eberhard Karls Universität Tübingen Germany (DE) Universität Hamburg (UHH) Germany (DE) University of Amsterdam Netherlands (NL) Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences Poland (PL) Humboldt-Universität zu Berlin Germany (DE) Institut national de physique nucléaire et de physique des particules (IN2P3) France (FR) University of the Free State South Africa (ZA) University of Oxford United Kingdom (GB) University of Warsaw / Uniwersytet Warszawski Poland (PL) University of Savoy Mont Blanc / Université Savoie Mont Blanc France (FR) University of the Witwatersrand (WITS) South Africa (ZA) University of Montpellier / Université Montpellier France (FR) University of Adelaide Australia (AU) Nicolaus Copernicus University (NCU) / Uniwersytet Mikołaja Kopernika w Toruniu (UMK) Poland (PL) Rikkyo University / 立教大学 Japan (JP) Université Paris-Saclay France (FR) Université de Bordeaux France (FR) Yerevan State University / Երեվանի Պետական Համալսարան (YSU) Armenia (AM)

How to cite

APA:

Aharonian, F., Benkhali, F.A., Aschersleben, J., Ashkar, H., Backes, M., Martins, V.B.,... Zywucka, N. (2024). H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883. Astronomy & Astrophysics, 687. https://doi.org/10.1051/0004-6361/202449612

MLA:

Aharonian, F., et al. "H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883." Astronomy & Astrophysics 687 (2024).

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