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

Palacio, Santiago; Benaglia, P.; Becker, M. De; Bosch‐Ramon, V.; Romero, Gustavo E.

doi:10.1017/pasa.2021.60

Cited by 4 publications

(8 citation statements)

References 36 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our limits are not compatible with their most optimistic results (see Fig. 2), suggesting that the magnetic field pressure as a fraction of the thermal pressure should be at least η B > 0.01 (consistent with the constrains on the integrated photon flux, see also Table 2 in del Palacio et al 2022). Together with upper limits on B from radio observations, this narrows the available parameter space to 0.01 η B 0.03.…”

Section: Discussionsupporting

confidence: 43%

“…Together with upper limits on B from radio observations, this narrows the available parameter space to 0.01 η B 0.03. Such a small range restricts the efficiency in converting the available kinetic power within the WCR into cosmic rays (CRs) to ξ CR ∼ 3 × 10 −2 (not far from estimates on η Carinae, see Farnier et al 2011;White et al 2020;del Palacio et al 2022, in stark contrast with the ξ γ results). Thus the underlying model assumptions might foster an overconfident parameter space exclusion.…”

Section: Discussionmentioning

confidence: 97%

“…SED of the WR-WR binary Apep as modelled by delPalacio et al (2022) for different fractions of the magnetic field energy density. It includes synchrotron emission and thermal bremsstrahlung (dashed lines), IC radiation (dot-dashed lines), and π 0 decay (dotted lines).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Limits on the non-thermal emission of the WR–WR system Apep

Martí-Devesa

Reimer

2023

A&A

View full text Add to dashboard Cite

Colliding-wind binaries (CWBs) constitute an emerging class of γ-ray sources powered by strong, dense winds in massive stellar systems. The most powerful of them are those binaries hosting a Wolf-Rayet (WR) star. Following the recent discovery of Apep – the closest known Galactic WR–WR binary – we discuss the non-detection of its putative high-energy emission by the Fermi Large Area Telescope (Fermi-LAT) in this Letter. The limits reported in the GeV regime can be used to set a lower limit on the magnetic field pressure density within the shocked wind-collision region (WCR), and to exclude Apep as a bright γ-ray emitting binary. Given that this WR–WR system is the most luminous CWB identified until now at radio wavelengths, this result proves unambiguously that non-thermal synchrotron emission is not a suitable identifier for the subset of γ-ray emitters in this class of particle accelerators. Rather, Apep could be an interesting case of study for magnetic field amplification in shocked stellar winds.

show abstract

Section: Discussionsupporting

confidence: 43%

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

Limits on the non-thermal emission of the WR–WR system Apep

Martí-Devesa

Reimer

2023

A&A

View full text Add to dashboard Cite

show abstract

“…Here we present a review of the multi-zone model used to calculate the non-thermal radiation from Apep. This model is suitable for this CWB as the stars are separated by tens of AU, which means that the shocks in the WCR are essentially adiabatic and quasi-stationary (del Palacio et al 2022). The WCR structure is treated as an axi-symmetric surface under a thin shock approximation (i.e., the fluid is considered homogeneous along the direction perpendicular to the shock normal).…”

Section: Appendix C: Non-thermal Emission Modelmentioning

confidence: 99%

“…Further constraints on the radio spectrum by Bloot et al (2022) allowed del to model the source broadband emission in order to infer properties of the stellar winds and predict the SED of the source at high energies. However, these predictions are highly degenerate as it is not possible to disentangle the relativistic particle energy distribution and the magnetic field strength in the WCR, B WCR , solely from radio data (del Palacio et al 2022). A recent analysis of Fermi-LAT data in γ-rays placed stronger constraints on the high-energy SED of Apep, but were still unable to detect its emission (Martí-Devesa et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

Palacio

García

Becker

et al. 2023

A&A

Self Cite

View full text Add to dashboard Cite

Context. Massive colliding-wind binaries (CWBs) can be non-thermal sources. The emission produced in their wind-collision region (WCR) encodes information of both the shocks properties and the relativistic electrons accelerated in them. The recently discovered system Apep, a unique massive system hosting two Wolf-Rayet stars, is the most powerful synchrotron radio emitter among the known CWBs, being an exciting candidate to investigate the non-thermal processes associated with stellar wind shocks. Aims. We intend to break the degeneracy between the relativistic particle population and the magnetic field strength in the WCR of Apep by probing its hard X-ray spectrum, where inverse-Compton (IC) emission is expected to dominate. Methods. We observe Apep with NuSTAR for 60 ks and combine this with a re-analysis of a deep archival XMM-Newton observation to better constrain the X-ray spectrum. We use a non-thermal emission model to derive physical parameters from the results. Results. We detect hard X-ray emission consistent with a power-law component from Apep. This is compatible with IC emission produced in the WCR for a magnetic field of ≈ 105-190 mG, corresponding to a magnetic-to-thermal pressure ratio in the shocks of ≈ 0.007-0.021, and a fraction of ∼ 1.5 × 10 −4 of the total wind kinetic power being transferred to relativistic electrons. Conclusions. This is the first time that the non-thermal emission from a CWB is detected both in radio and high energies. This allows us to derive the most robust constraints of the particle acceleration efficiency and magnetic field intensity in a CWB so far, reducing the typical uncertainty of a few orders of magnitude to just within a factor of a few. This constitutes an important step forward in our characterisation of the physical properties of CWBs.

show abstract

eROSITA studies of the Carina nebula

Sasaki,

Robrade,

Krause

et al. 2024

A&A

View full text Add to dashboard Cite

During the first four all-sky surveys that eRASS:4 carried out from December 2019 to 2021, the extended Roentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma (Spektr-RG, SRG) observed the Galactic region of the Carina nebula. We analysed the eRASS:4 data to study the distribution and spectral properties of the hot interstellar plasma and the bright stellar sources in the Carina nebula. The spectral extraction regions of the diffuse emission were defined based on the X-ray spectral morphology and multi-wavelength data. The spectra were fit with a combination of thermal and non-thermal emission models. The X-ray bright point sources in the Carina nebula are the colliding wind binary eta Car, several O stars, and Wolf-Rayet (WR) stars. We extracted the spectra of the brightest stellar sources, which can be well fit with a multi-component thermal plasma model. The spectra of the diffuse emission in the brighter parts of the Carina nebula are well reproduced by two thermal models, a lower-temperature component (sim 0.2 keV) and a higher-temperature component (0.6 -- 0.8 keV). An additional non-thermal component dominates the emission above sim 1 keV in the central region around eta Car and the other massive stars. Significant orbital variation in the X-ray flux was measured for eta Car, WR 22, and WR 25. eta Car requires an additional time-variable thermal component in the spectral model, which is associated with the wind-wind collision zone. Properties such as temperature, pressure, and luminosity of the X-ray emitting plasma in the Carina nebula derived from the eROSITA data are consistent with theoretical calculations of emission from superbubbles. This confirms that the X-ray emission is caused by the hot plasma inside the Carina nebula that has been shocked-heated by the stellar winds of the massive stars, in particular, of eta Car.

show abstract

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

Cited by 4 publications

References 36 publications

Limits on the non-thermal emission of the WR–WR system Apep

Limits on the non-thermal emission of the WR–WR system Apep

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

eROSITA studies of the Carina nebula

Contact Info

Product

Resources

About