The prototype X-ray binary GX 339–4: using TeV γ-rays to assess LMXBs as Galactic cosmic ray accelerators

Kantzas, Dimitrios; Markoff, Sera; Lucchini, Matteo; Ceccobello, Chiara; Grinberg, V.; Connors, Riley; Uttley, P.

doi:10.1093/mnras/stac004

Cited by 10 publications

(11 citation statements)

References 180 publications

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“…3). However, despite this positional coincidence, we consider an association of 4U 1642−45 with HESS J1646−458 -or even the emission observed just in region A -highly unlikely: LMXBs are not known emitters of γ rays in the TeV energy range, in fact, Kantzas et al (2022) have recently shown that even the upcoming Cherenkov Telescope Array (CTA) will be able to detect LMXB outbursts only under favourable circumstances. Moreover, the observed emission is spatially extended, which would be unexpected if it is produced inside a transient jet.…”

Section: U 1642-45mentioning

confidence: 82%

A deep spectromorphological study of theγ-ray emission surrounding the young massive stellar cluster Westerlund 1

Aharonian

Ashkar

Backes

et al. 2022

A&A

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Context. Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) that are accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy, is a prime candidate for studying this hypothesis. While the veryhigh-energy γ-ray source HESS J1646−458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. Aims. We aim to identify the physical processes responsible for the γ-ray emission around Westerlund 1 and thus to understand the role of massive stellar clusters in the acceleration of Galactic CRs better. Methods. Using 164 hours of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the γ-ray emission of HESS J1646−458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. Results. We detected large-scale (∼2 • diameter) γ-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with γ-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and it is uniform across the entire source region. We did not find a clear correlation of the γ-ray emission with gas clouds as identified through H I and CO observations. Conclusions. We conclude that, of the known objects within the region, only Westerlund 1 can explain the majority of the γ-ray emission. Several CR acceleration sites and mechanisms are conceivable and discussed in detail. While it seems clear that Westerlund 1 acts as a powerful particle accelerator, no firm conclusions on the contribution of massive stellar clusters to the flux of Galactic CRs in general can be drawn at this point.

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Section: U 1642-45mentioning

confidence: 82%

A deep spectromorphological study of theγ-ray emission surrounding the young massive stellar cluster Westerlund 1

Aharonian

Ashkar

Backes

et al. 2022

A&A

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“…With the conserved, mass-loading jet model we develop here, we are able to constrain the total energy that is allocated to the protons and is used to accelerate them to non-thermal energies. In that way, the total energy carried by the accelerated protons never exceeds the available energy of the jets that has been a major issue in the past (Böttcher et al 2013;Zdziarski & Böttcher 2015;Liodakis & Petropoulou 2020;Kantzas et al 2022). In Fig.…”

Section: Proton Energy Crisismentioning

confidence: 92%

“…The acceleration efficiency 𝑓 sc depends on the particle acceleration mechanism, but we fix it at a value between 0.01 and 0.1 leading to a maximum electron energy of the order of GeV for the case of a BHXB. For the lepto-hadronic scenario, we assume that protons accelerate as well in a power law from an 𝜀 min = 1 to some 𝜀 max that we calculate by equating the acceleration timescale to the (lateral) escape timescale 𝑟/c of the jet segment and for the case of BHXBs it may attain values of the order of 100 TeV and above (Pepe et al 2015;Kantzas et al 2021Kantzas et al , 2022. We constrain the non-thermal particle distributions by assuming that they extend up to the maximum energy, and then they drop exponentially…”

Section: The Acceleration Region and Particle Accelerationmentioning

confidence: 99%

“…The increased energy available for non-thermal proton acceleration allows for a stronger TeV flux, which is dominated by the neutral pion decay due to p𝛾 interactions. Such TeV flux, depending on the distance of the BHXB (see, e.g., Kantzas et al 2022) might be significant to be detected by current TeV facilities, such as the Large High Altitude Air Shower Observatory (LHAASO) or future 𝛾-ray facilities, such as the Cherenkov Telescope Array (CTA). The fact that an initially pair dominated jet can potentially lead to a stronger TeV flux may sound counterintuitive, but in fact it is natural in our treatment due to the assumption that the mass loading is linked with energy dissipation into particle acceleration.…”

Section: Mass-loaded Jets -Hadjetmentioning

confidence: 99%

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Exploring the role of composition and mass-loading on the properties of hadronic jets

Kantzas¹,

Markoff²,

Lucchini³

et al. 2023

Preprint

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Astrophysical jets are relativistic outflows that remain collimated for remarkably many orders of magnitude. Despite decades of research, the origin of cosmic rays (CRs) remains unclear, but jets launched by both supermassive black holes in the centre of galaxies and stellar-mass black holes harboured in X-ray binaries (BHXBs) are among the candidate sources for CR acceleration. When CRs accelerate in astrophysical jets, they initiate particle cascades that form 𝛾-rays and neutrinos. In the so-called hadronic scenario, the population of accelerated CRs requires a significant amount of energy to properly explain the spectral constraints similarly to a purely leptonic scenario. The amount of energy required often exceeds the Eddington limit, or even the total energy available within the jets. The exact energy source for the accelerated protons is unclear, but due to energy conservation along the jets, it is believed to come from the jet itself via transfer of energy from the magnetic fields, or kinetic energy from the outflow. To address this hadronic energy issue and to self-consistently evolve the energy flux along the flows, we explore a novel treatment for including hadronic content, in which instabilities along the jet/wind border play a critical role. We discuss the impact of the different jet composition on the jet dynamics for a pair dominated and an electron-proton jet, and consequently the emitted spectrum, accounting for both leptonic and hadronic processes. Finally, we discuss the implications of this mass-loading scenario to address the proton energy issue.

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“…If Γ 1, this difference is negligible. 1 We note that Lucchini et al (2021) and Kantzas et al (2022) used a for-The Poynting flux in an ideal-MHD jet (i.e., with the electric vector perpendicular to the magnetic one,…”

Section: The Jet Structurementioning

confidence: 99%

A simple analytical model of magnetic jets

Zdziarski,

Stawarz,

Sikora

et al. 2022

Preprint

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We propose a simple analytical jet model of magnetic jets, utilizing conservation laws and some results of published GRMHD jet simulations, and consider radially-averaged profiles of the physical quantities. We take into account conversion of the magnetic energy flux to bulk acceleration in jets formed around rotating black holes assuming the mass continuity equation and constant jet power, leading to the Bernoulli equation. For assumed profiles of the bulk Lorentz factor and the radius, this gives the profile of toroidal magnetic field component along the jet. We then consider the case where the poloidal field component is connected to a rotating black hole surrounded by an accretion disc. The formalism recovers the standard formula for the power extracted from a rotating black hole. We find that the poloidal field strength dominates over the toroidal one in the comoving frame up to large distances, which means that jets should be more stable to current-driven kink modes. The resulting magnetic field profiles can then be used to calculate the jet synchrotron emission.

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The prototype X-ray binary GX 339–4: using TeV γ-rays to assess LMXBs as Galactic cosmic ray accelerators

Cited by 10 publications

References 180 publications

A deep spectromorphological study of theγ-ray emission surrounding the young massive stellar cluster Westerlund 1

A deep spectromorphological study of theγ-ray emission surrounding the young massive stellar cluster Westerlund 1

Exploring the role of composition and mass-loading on the properties of hadronic jets

A simple analytical model of magnetic jets

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