A model for the non-thermal emission of the very massive colliding-wind binary HD 93129A

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

doi:10.1051/0004-6361/201628264

Cited by 30 publications

(62 citation statements)

References 50 publications

(79 reference statements)

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“…Theoretical predictions are strongly dependent of some parameters, such as the magnetic field that can drain the energy of electrons before they are able to produce a significant amount of gamma rays by IC scattering of stellar photons. Nevertheless, luminosities in the range 10 32 -10 34 erg s −1 can be expected from sources similar to HD 93129A (see del Palacio et al 2016).…”

Section: High-energy Observationsmentioning

confidence: 99%

An investigation into the fraction of particle accelerators among colliding-wind binaries

Becker

Benaglia

Romero

et al. 2017

A&A

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Particle-accelerating colliding-wind binaries (PACWBs) are multiple systems made of early-type stars able to accelerate particles up to relativistic velocities. The relativistic particles can interact with different fields (magnetic or radiation) in the colliding-wind region and produce non-thermal emission. In many cases, non-thermal synchrotron radiation might be observable and thus constitute an indicator of the existence of a relativistic particle population in these multiple systems. To date, the catalogue of PACWBs includes about 40 objects spread over many stellar types and evolutionary stages, with no clear trend pointing to privileged subclasses of objects likely to accelerate particles. This paper aims at discussing critically some criteria for selecting new candidates among massive binaries. The subsequent search for non-thermal radiation in these objects is expected to lead to new detections of particle accelerators. On the basis of this discussion, some broad ideas for observation strategies are formulated. At this stage of the investigation of PACWBs, there is no clear reason to consider particle acceleration in massive binaries as an anomaly or even as a rare phenomenon. We therefore consider that several PACWBs will be detected in the forthcoming years, essentially using sensitive radio interferometers which are capable of measuring synchrotron emission from colliding-wind binaries. Prospects for high-energy detections are also briefly addressed.

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Section: High-energy Observationsmentioning

confidence: 99%

An investigation into the fraction of particle accelerators among colliding-wind binaries

Becker

Benaglia

Romero

et al. 2017

A&A

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“…We applied the NT emission model described in del Palacio et al (2016) to test whether turbulent MR can account for the accelerated particles in WR 146. This model considers the adiabatic wind shocks to be thin enough to neglect their width, and that the relativistic particles are attached to the flow streamlines through the chaotic B-component.…”

Section: Turbulent Magnetic Reconnectionmentioning

confidence: 99%

Synchrotron radiation and absence of linear polarization in the colliding wind binary WR 146

Hales

Benaglia

Palacio

et al. 2017

A&A

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Context. Several massive early-type binaries exhibit non-thermal emission which has been attributed to synchrotron radiation from particles accelerated by diffusive shock acceleration (DSA) in the wind-collision region (WCR). If the magnetic field in the strong shocks is ordered, its component parallel to the shock front should be enhanced, and the resultant synchrotron radiation would be polarized. However, such polarization has never been measured. Aims. We aim to determine the percentage of linearly polarized emission from the well-known non-thermal radio emitter WR 146, a WC6+O8 system. Methods. We performed spatially-unresolved radio continuum observations of WR 146 at 5 cm and 20 cm with the Karl G. Jansky Very Large Array. We constructed a numerical model to investigate a scenario where particles are accelerated by turbulent magnetic reconnection (MR), and we performed a quantitative analysis of possible depolarization effects. Results. No linearly polarized radio emission was detected. The data constrain the fractional linear polarization to less than 0.6% between 1 to 8 GHz. This is compatible with a high level of turbulence and a dominant random component in the magnetic field. In this case the relativistic particles could be produced by turbulent magnetic reconnection. In order for this scenario to satisfy the required non-thermal energy budget, the strength of the magnetic field in the WCR must be as high as ∼ 150 mG. However, if the magnetic field is ordered and DSA is ongoing, then a combination of internal and external Faraday rotation could equally account for the depolarization of the emission. Conclusions. The absence of polarization could be caused by a highly turbulent magnetic field, other depolarization mechanisms such as Faraday rotation in the stellar wind, or a combination of these processes. It is not clear whether it is possible to develop the high level of turbulence and strong magnetic fields required for efficient MR in a long-period binary such as WR 146. This scenario might also have trouble explaining the low-frequency cutoff in the spectrum. We therefore favor a scenario where particles are accelerated through DSA and the depolarization is produced by mechanisms other than a large ratio between random to regular magnetic fields.

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“…Another possibility is that the TeV emission could be produced by massive colliding wind binaries (see e.g., Reimer et al 2006). However, the TeV luminosity of HESS J1616 is too large (∼3×10 34 erg s −1 at 3.7 kpc) to be consistent with this scenario, assuming a similar particle injection spectrum and model as in del Palacio et al (2016). Also, the size of the TeV source is much larger than the cluster size.…”

Section: Field 1 Source 25 (Cxou J1617036-504705)mentioning

confidence: 80%

Chandra Observations of the Field Containing HESS J1616–508

Hare

Kargaltsev

Pavlov³

et al. 2017

ApJ

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We report the results of three Chandra observations covering most of the extent of the TeV γ-ray source HESS J1616-508 and a search for a lower-energy counterpart to this source. We detect 56 X-ray sources, 37 of which have counterparts at lower frequencies, including a young massive star cluster, but none of them appear to be a particularly promising counterpart to the TeV source. The brightest X-ray source, CXOU J161423.4-505738, with a fluxF 0.5-7 keV ≈5×10 −13 erg cm −2 s −1 , has a hard spectrum that is well fit by a power-law model with a photon index Γ=0.2±0.3 and is a likely intermediate polar CV candidate. No counterparts of this source were detected at other wavelengths. CVs are not known to produce extended TeV emission, and the source is also largely offset (19′) from HESS J1616-508, making them unlikely to be associated. We have also set an upper limit on the X-ray flux of PSR J1614-5048 in the 0.5-8 keV band (F 0.5-8 keV <5×10−15 erg cm −2 s −1 at a 90% confidence level). This makes PSR J1614-5048 one of the least X-ray-efficient pulsars known, with an X-ray0.5 8 keV 0.5 8 keV 5 . We find no evidence supporting the association between the pulsar and the TeV source. We rule out a number of X-ray sources as possible counterparts to the TeV emission and do not find a plausible counterpart among the other sources. Lastly, we discuss the possible relation of PSR J1617-5055 to HESS J1616-508 in light of the new observations.

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A model for the non-thermal emission of the very massive colliding-wind binary HD 93129A

Cited by 30 publications

References 50 publications

An investigation into the fraction of particle accelerators among colliding-wind binaries

An investigation into the fraction of particle accelerators among colliding-wind binaries

Synchrotron radiation and absence of linear polarization in the colliding wind binary WR 146

Chandra Observations of the Field Containing HESS J1616–508

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