The high-energy emission from HD 93129A near periastron

Palacio, Santiago; García, Federico; Altamirano, D.; Barbá, R. H.; Bosch‐Ramon, V.; Corcoran, M. F.; Becker, M. De; Hamaguchi, Kenji; Apellániz, J. Maíz; Adrover, P. Munar; Paredes, J. M.; Romero, Gustavo E.; Sana, H.; Tavani, M.; ud‐Doula, Asif

doi:10.1093/mnras/staa1156

Cited by 8 publications

(12 citation statements)

References 49 publications

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“…Nonetheless, a possible hardening of the particle energy distribution at high energies could potentially increase the γ -ray luminosity significantly (e.g. del Palacio et al 2016Palacio et al , 2020. We also note that the radiation from secondary pairs created in γ − γ interactions is negligible because the soft γ -ray spectrum leads to much less power being radiated above 100 GeV than below 100 GeV, so the pair energetics is small.…”

Section: High-energy Spectral Energy Distributionmentioning

confidence: 79%

“…With this end, we further investigate the possibility of constraining a putative power-law component in the hard X-ray spectrum, as can be expected for a bright CWB (e.g. Hamaguchi et al 2018;del Palacio et al 2020). Given that the source is not significantly variable, we choose to analyse the XMM-Newton observation ObsID 0201500101, for which the source is pointed closest to on-axis and is observed with all EPIC cameras.…”

Section: Observations In the X-ray Bandmentioning

confidence: 99%

“…This intrinsic emission is then corrected for absorption in the local matter and radiation fields. In Appendix A, we present a slight modification on how the particle energy distribution is calculated with respect to the base model in del Palacio et al (2020).…”

Section: Emission Modelmentioning

confidence: 99%

“…by radio data alone, but predictions in the high-energy domain can help to break this degeneracy (e.g. delPalacio et al 2020). Here, we calculate the expected fluxes in different energy bands accessible to current facilities.…”

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confidence: 99%

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The non-thermal emission from the colliding-wind binary Apep

Palacio

Benaglia

Becker

et al. 2022

Publ. Astron. Soc. Aust.

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Therecently discovered massive binary system Apep is the most powerful synchrotron emitter among the known Galactic colliding-wind binaries. This makes this particular system of great interest to investigate stellar winds and the non-thermal processes associated with their shocks. This source was detected at various radio bands, and in addition the wind-collision region was resolved by means of very-long baseline interferometric observations. We use a non-thermal emission model for colliding-wind binaries to derive physical properties of this system. The observed morphology in the resolved maps allows us to estimate the system projection angle on the sky to be $\psi \approx 85^\circ$ . The observed radio flux densities also allow us to characterise both the intrinsic synchrotron spectrum of the source and its modifications due to free–free absorption in the stellar winds at low frequencies; from this, we derive mass–loss rates of the stars of $\dot{M}_\mathrm{WN} \approx 4\times10^{-5}\;\mathrm{M}_\odot\,\mathrm{yr}^{-1}$ and $\dot{M}_\mathrm{WC} \approx 2.9\times10^{-5}\;\mathrm{M}_\odot\,\mathrm{yr}^{-1}$ . Finally, the broadband spectral energy distribution is calculated for different combinations of the remaining free parameters, namely the intensity of the magnetic field and the injected power in non-thermal particles. We show that the degeneracy of these two parameters can be solved with observations in the high-energy domain, most likely in the hard X-rays but also possibly in $\gamma$ -rays under favourable conditions.

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Section: High-energy Spectral Energy Distributionmentioning

confidence: 79%

Section: Observations In the X-ray Bandmentioning

confidence: 99%

Section: Emission Modelmentioning

confidence: 99%

mentioning

confidence: 99%

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The non-thermal emission from the colliding-wind binary Apep

Palacio

Benaglia

Becker

et al. 2022

Publ. Astron. Soc. Aust.

Self Cite

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“…Taking into account the emission from the relativistic particles in the WCR, the spectrum should be modelled as a combination of a thermal and a non-thermal (power-law) component, such as tbabs * (apec + po) (c.f. del Palacio et al, 2020). For the power-law component we fix the photon spectral index to the expected value of Γ = 1 − α = 1.71 (see forthcoming Sec.…”

Section: Observations In the X-ray Bandmentioning

confidence: 99%

The non-thermal emission from the colliding-wind binary Apep

del Palacio,

Benaglia,

De Becker

et al. 2021

Preprint

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The recently discovered massive binary system Apep is the most powerful synchrotron emitter among the known Galactic colliding-wind binaries. This makes this particular system of great interest to investigate stellar winds and the non-thermal processes associated with their shocks. This source was detected at various radio bands, and in addition the wind-collision region was resolved by means of very-long baseline interferometric observations. We use a non-thermal emission model for colliding-wind binaries to derive physical properties of this system. The observed morphology in the resolved maps allows us to estimate a value of ψ ≈ 85 • for the system projection angle on the sky. The observed radio fluxes also allow us to characterise both the intrinsic synchrotron spectrum of the source and its modifications due to free-free absorption in the stellar winds at low frequencies; from this we derive mass-loss rates of the stars of ṀWN ≈ 4 × 10 −5 M yr −1 and ṀWC ≈ 2.9 × 10 −5 M yr −1 . Finally, the broadband spectral energy distribution is calculated for different combinations of the remaining free parameters, namely the intensity of the magnetic field and the injected power in non-thermal particles. We show that the degeneracy of these two parameters can be solved with observations in the high-energy domain, most likely in the hard X-rays but also possibly in γ-rays under favourable conditions.

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η Carinae with Fermi-LAT: two full orbits and the third periastron

Martí-Devesa

Reimer

2021

A&A

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Context. Colliding-wind binaries are massive stellar systems featuring strong, interacting winds. These binaries may be actual particle accelerators, making them variable γ-ray sources due to changes in the wind collision region along the orbit. However, only two of these massive stellar binary systems have been identified as high-energy sources. The first and archetypical system of this class is η Carinae, a bright γ-ray source with orbital variability peaking around its periastron passage. Aims. The origin of the high-energy emission in η Carinae is still unclear, with both lepto-hadronic and hadronic scenarios being under discussion. Moreover, the γ-ray emission seemed to differ between the two periastrons previously observed with the Fermi-Large Area Telescope. Continuing observations might provide highly valuable information for understanding the emission mechanisms in this system. Methods. We have used almost 12 yr of data from the Fermi-Large Area Telescope. We studied both low- and high-energy components, searching for differences and similarities between both orbits, and we made use of this large dataset to search for emission from nearby colliding-wind binaries. Results. We show how the energy component above 10 GeV of η Carinae peaks months before the 2014 periastron, while the 2020 periastron is the brightest one to date. Additionally, upper limits are provided for the high-energy emission in other particle-accelerating colliding-wind systems. Conclusions. Current γ-ray observations of η Carinae strongly suggest that the wind collision region of this system is perturbed from orbit to orbit, affecting particle transport within the shock.

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The high-energy emission from HD 93129A near periastron

Cited by 8 publications

References 49 publications

The non-thermal emission from the colliding-wind binary Apep

The non-thermal emission from the colliding-wind binary Apep

The non-thermal emission from the colliding-wind binary Apep

η Carinae with Fermi-LAT: two full orbits and the third periastron

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