Very high energy gamma rays from the direction of Sagittarius A<sup>*</sup>

Aharonian, F.; Akhperjanian, A. G.; Aye, K.-M.; Bazer‐Bachi, A. R.; Beilicke, M.; Benbow, W.; Berge, D.; Berghaus, P.; Bernlöhr, K.; Bolz, O.; Boisson, C.; Borgneier, C.; Breitling, F.; Brown, A. M.; Gordo, J. Bussons; Chadwick, P. M.; Chitnis, V. R.; Chounet, L.‐M.; Cornils, R.; Degrange, B.; Djannati‐Ataï, A.; Drury, L. O’c.; Ergin, T.; Espigat, P.; Feinstein, F.; Fleury, P.; Fontaine, G.; Funk, S.; Gallant, Y. A.; Giebels, B.; Gillessen, S.; Goret, P.; Guy, J.; Hadjichristidis, C.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Holleran, M.; Horns, D.; Jager, O. C. de; Jung, I.; Khélifi, B.; Komin, Nu.; Konopelko, A.; Latham, I. J.; Gallou, R. Le; Lemoine, Martin; Leroy, N.; Löhse, T.; Marcowith, A.; Masterson, C.; McComb, T. J. L.; Naurois, M. de; Nolan, S. J.; Noutsos, A.; Orford, K. J.; Ouchrif, M.; Panter, M.; Pelletier, G.; Pita, S.; Pohl, M.; Pühlhofer, G.; Punch, M.; Raubenheimer, Britt; Raue, M.; Raux, J.; Redondo, I.; Reimer, A.; Ripken, J.; Rivoal, M.; Rob, L.; Rolland, L.; Rowell, G.; Sahakian, V.; Saugé, L.; Schlenker, S.; Schuster, C.; Schwanke, U.; Siewert, M.; Sol, H.; Steenkamp, R.; Stegmann, C.; Tavernet, J.‐P.; Théoret, C. G.; Tluczykont, M.; Walt, D. J. van der; Vasileiadis, G.; Vincent, P.; Visser, Bart; Völk, H. J.; Wagner, S. J.

doi:10.1051/0004-6361:200400055

Cited by 370 publications

(201 citation statements)

References 24 publications

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“…At higher energies than is accessible by the LAT, there is now firm evidence from HESS (Aharonian et al, 2004) and MAGIC (Albert et al, 2006) for a point source, HESS J1745-290, that is coincident with the position of Sgr A*. The energy spectrum of this source is dN/dE E −2.1 , and there is a cutoff in the spectrum at approximately 15 TeV.…”

Section: Galactic Centermentioning

confidence: 96%

Galactic searches for dark matter

2013

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For nearly a century, more mass has been measured in galaxies than is contained in the luminous stars and gas. Through continual advances in observations and theory, it has become clear that the dark matter in galaxies is not comprised of known astronomical objects or baryonic matter, and that identification of it is certain to reveal a profound connection between astrophysics, cosmology, and fundamental physics. The best explanation for dark matter is that it is in the form of a yet undiscovered particle of nature, with experiments now gaining sensitivity to the most well-motivated particle dark matter candidates. In this article, I review measurements of dark matter in the Milky Way and its satellite galaxies and the status of Galactic searches for particle dark matter using a combination of terrestrial and space-based astroparticle detectors, and large scale astronomical surveys. I review the limits on the dark matter annihilation and scattering cross sections that can be extracted from both astroparticle experiments and astronomical observations, and explore the theoretical implications of these limits. I discuss methods to measure the properties of particle dark matter using future experiments, and conclude by highlighting the exciting potential for dark matter searches during the next decade, and beyond.

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Section: Galactic Centermentioning

confidence: 96%

Galactic searches for dark matter

2013

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“…data at 68%, 90% and 95% confidence levels for cutoffs at 2.9 PeV, 0.6 PeV and 0.4 PeV, respectively. This is the first robust detection of a VHE cosmic hadronic accelerator which operates as a PeVatron.Remarkably, the Galactic Centre PeVatron appears to be located in the same region as the central γ-ray source HESS J1745-290 [11][12][13][14] . Unfortunately, the current data cannot provide an answer as to whether there is an intrinsic link between these two objects.…”

mentioning

confidence: 99%

“…Remarkably, the Galactic Centre PeVatron appears to be located in the same region as the central γ-ray source HESS J1745-290 [11][12][13][14] . Unfortunately, the current data cannot provide an answer as to whether there is an intrinsic link between these two objects.…”

mentioning

confidence: 99%

Acceleration of petaelectronvolt protons in the Galactic Centre

Abramowski¹,

Aharonian²,

Benkhali³

et al. 2016

Nature

402

229

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Galactic cosmic rays reach energies of at least a few Peta-electronvolts (1 PeV =1015 electron volts)1 . This implies our Galaxy contains PeV accelerators (PeVatrons), but all proposed models of Galactic cosmic-ray accelerators encounter non-trivial difficulties at exactly these energies 2 . Tens of Galactic accelerators capable of accelerating particle to tens of TeV (1 TeV =10 12 electron volts) energies were inferred from recent gamma-ray observations 3 . None of the currently known accelerators, however, not even the handful of shell-type supernova remnants commonly believed to supply most Galactic cosmic rays, have shown the characteristic tracers of PeV particles: power-law spectra of gamma rays extending without a cutoff or a spectral break to tens of TeV 4 . Here we report deep gamma-ray observations with arcminute angular resolution of the Galactic Centre regions, which show the expected tracer of the presence of PeV particles within the central 10 parsec of the Galaxy. We argue that the supermassive black hole Sagittarius A* is linked to this PeVatron. Sagittarius A* went through active phases in the past, as demonstrated by X-ray outbursts 5 and an outflow from the Galactic Center 6 . Although its current rate of particle acceleration is not sufficient to provide a substantial contribution to Galactic cosmic rays, Sagittarius A* could have plausibly been more active over the last 10 6−7 years, and therefore should be considered as a viable alternative to supernova remnants as a source of PeV Galactic cosmic rays.The large photon statistics accumulated over the last 10 years of observations with the High Energy Stereoscopic System (H.E.S.S.), together with improvements in the methods of data analysis, allow for a deep study of the properties of the diffuse very-high-energy (VHE; more than 100 GeV) emission of the central molecular zone. This region surrounding the Galactic Centre contains predominantly molecular gas and extends (in projection) out to r∼250 pc at positive galactic longitudes and r∼150 pc at negative longitudes. The map of the central molecular zone as seen in VHE γ-rays (Fig. 1) shows a strong (although not linear; see below) correlation between the brightness distribution of VHE γ-rays and the locations of massive gas-rich complexes. This points towards a hadronic origin of the diffuse emission 7 , where the γ-rays result from the interactions of relativistic protons with the ambient gas. The second important mechanism of production of VHE γ-rays 3 is the inverse Compton scattering of electrons. However, the severe radiative losses suffered by multi-TeV electrons in the Galactic Centre region prevent them from propagating over scales comparable to the size of the central molecular zone, thus disfavouring a leptonic origin of the γ-rays (see discussion in Methods and Extended Data Figures 1 and 2). The location and the particle injection rate history of the cosmic-ray accelerator(s), responsible for the relativistic protons, determine the spatial distribution of these cosmic rays which...

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“…Early H.E.S.S. observations of the GC region led to the detection of a point-like source of VHE γ-rays at the gravitational centre of the Galaxy (HESS J1745−290) [6], compatible with the positions of the supermassive black hole Sagittarius A ⋆ , the supernova remnant (SNR) Sgr A East, and a GC source reported by other groups [7,8]. A more sensitive exposure of the region in 2004 revealed a second source: the supernova remnant/pulsar wind nebula G 0.9+0.1 [9].…”

mentioning

confidence: 99%