Search for long-term variability of HESS J1745-290

At the center of our Galaxy lies the bright γ -ray point-like source HESS J1745-290, which is compatible in position with Sgr A ⋆ , although an association between the two remains uncertain. Using data obtained between 2004 and 2019 with the High Energy Stereoscopic System (H.E.S.S.) on the Galactic center region, we studied the variability of HESS J1745-290 over 353 hours of observations collected over 16 years, representing the largest dataset gathered yet on this region at TeV energies. We performed a 3D maximum-likelihood analysis of the central source and the diffuse γ -ray emission in the Galactic center region. This analysis allowed us to extract the spectral and morphological intrinsic behavior of the two components. By performing this analysis on an annual basis, we derived the light curve of HESS J1745-290 and the diffuse emission over the past 16 years. The 3D maximum-likelihood analysis method allowed us to separate the central source from the overlapping diffuse emission, enabling a recalibration of the former by the latter and alleviating some of the systematic effects. We find no long-term or yearly variability. We also provide an estimate of the sensitivity of H.E.S.S. to variation of this specific source over 16 years. We rule out any yearly γ -ray flux variation of this source larger than 30%, as well as any linear flux variation exceeding 30% over this time period.

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Journal
Astronomy and Astrophysics
Published
2026-05-01
DOI
https://doi.org/10.1051/0004-6361/202557676
Primary Topic
Astrophysical Phenomena and Observations
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article
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article

Search for long-term variability of HESS J1745-290

K. Feijen, V. Sahakian, D. Malyshev, A. Mitchell et al.
Astronomy and Astrophysics
Astrophysical Phenomena and Observations
article

Search for long-term variability of HESS J1745-290

K. Feijen, V. Sahakian, D. Malyshev, A. Mitchell, R. Batzofin, I. Jung-Richardt, F. Aharonian, M Sasaki, D. Berge, M.G.F. Mayer, C Boisson, M. O. Moghadam, P. Pichard, K. Kosack, M. Backes, P. Goswami, E. de Oña Wilhelmi, K. Bernlöhr, A. Quirrenbach, U. Pensec, J. Glombitza, N. Komin, T. Preis, C. Burger-Scheidlin, B. Reville, C. Escañuela Nieves, G. Rowell, T. L. Holch, F Brun, J Bolmont, F Schüssler, M Cerruti, B Khélifi, A Djannati-Ataï, B. Cornejo, M. Punch, J. de Assis Scarpin, O. Reimer, K. Sabri, S. Gabici, R. D. Parsons, G. Fontaine, W. Si Said, J. Celic, A. Dmytriiev, A. Lemière, J. F. Glicenstein, R. G. Lang, M. D. Filipovic, J. A. Hinton, S. Panny, M. Lemoine-Goumard, I. Reis, D. Kerszberg, M. Chernyakova, M. Holler, W. Hofmann, J. Mackey, I. Jaroschewski, L. Olivera-Nieto, A. Montanari, Ł. Stawarz, B. Bruno, M. de Naurois, F. Jankowsky, A. Acharyya, D. Horns, G. Cotter, S. Funk, F. Rieger, J. Devin, J.-P. Lenain, H. X. Ren, A. Santangelo, J.-P. Ernenwein, T. Bylund, D. Kostunin, O. Chibueze, J. Damascene Mbarubucyeye, A. Mehta, G. Pühlhofer, K. Egg, M. Böttcher, A. Chen, A. Reimer, P. Fauverge, M. de Bony de Lavergne, A. G. Delgado Giler, J. O. Chibueze, M. Jamrozy, R. Moderski, P. Liniewicz, L. Heckmann, V. Marandon, B. Rudak, H. Sol, S. Lazarević, J. Niemiec, B. Hess, L. Mohrmann
article en

Abstract

At the center of our Galaxy lies the bright γ -ray point-like source HESS J1745-290, which is compatible in position with Sgr A ⋆ , although an association between the two remains uncertain. Using data obtained between 2004 and 2019 with the High Energy Stereoscopic System (H.E.S.S.) on the Galactic center region, we studied the variability of HESS J1745-290 over 353 hours of observations collected over 16 years, representing the largest dataset gathered yet on this region at TeV energies. We performed a 3D maximum-likelihood analysis of the central source and the diffuse γ -ray emission in the Galactic center region. This analysis allowed us to extract the spectral and morphological intrinsic behavior of the two components. By performing this analysis on an annual basis, we derived the light curve of HESS J1745-290 and the diffuse emission over the past 16 years. The 3D maximum-likelihood analysis method allowed us to separate the central source from the overlapping diffuse emission, enabling a recalibration of the former by the latter and alleviating some of the systematic effects. We find no long-term or yearly variability. We also provide an estimate of the sensitivity of H.E.S.S. to variation of this specific source over 16 years. We rule out any yearly γ -ray flux variation of this source larger than 30%, as well as any linear flux variation exceeding 30% over this time period.

Astronomy and AstrophysicsVol. 709
Jagiellonian University (PL), Centre National de la Recherche Scientifique (FR), Dublin Institute For Advanced Studies (IE), A. Alikhanyan National Laboratory (AM), Université de Bordeaux (FR), Universität Hamburg (DE), University of Potsdam (DE), University of Southern Denmark (DK), Friedrich-Alexander-Universität Erlangen-Nürnberg (DE), Universität Innsbruck (AT), University of the Witwatersrand (ZA), Université de Montpellier (FR), Université Paris Cité (FR), Aix-Marseille Université (FR), University of Namibia (NA), Heidelberg University (DE), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris Sciences et Lettres (FR), North-West University (ZA), Université Paris-Saclay (FR), Deutsches Elektronen-Synchrotron DESY (DE), Laboratoire AstroParticule et Cosmologie (FR), Humboldt-Universität zu Berlin (DE), Sorbonne Université (FR), University of Oxford (GB), Laboratoire Univers et Particules de Montpellier (FR), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), International Center for Relativistic Astrophysics (IT), CEA Paris-Saclay (FR), Astronomical Institute of the Slovak Academy of Sciences (SK), Hamburg Institut (Germany) (DE), Nicolaus Copernicus Astronomical Center (PL), Polish Mother’s Memorial Hospital Research Institute (PL), Thüringer Landessternwarte Tautenburg (DE), Max Planck Institute for Nuclear Physics (DE), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), The University of Adelaide (AU), Western Sydney University (AU), University of Tübingen (DE), University of Amsterdam (NL), Polish Academy of Sciences (PL)
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