Multiwavelength Astronomy and CTA: X-rays

Context. Recently, the colliding-wind region of the binary stellar system HD 93129A was resolved for the first time using Very Large Baseline Interferometry. This system, one of the most massive known binaries in our Galaxy, presents non-thermal emission in the radio band, which can be used to infer the physical conditions in the system, and make predictions for the high-energy band. Aims. We intend to constrain some of the unknown parameters of HD 93129A through modeling the non-thermal emitter. We also aim to analyse the detectability of this source in hard X-rays and γ-rays. Finally, we want to predict how the non-thermal emission will evolve in the future, when the stars approach periastron. Methods. A broadband radiative model for the wind-collision region (WCR) has been developed taking into account the evolution of the accelerated particles streaming along the shocked region, the emission by different radiative processes, and the attenuation of the emission propagating through the local matter and radiation fields. We reproduce the available radio data, and make predictions of the emission in hard X-rays and γ-rays under different assumptions.Results. From the analysis of the radio emission, we find that the binary HD 93129A is more likely to have a low inclination and a high eccentricity, with the more massive star being currently closer to the observer. The minimum energy of the non-thermal electrons seems to be between ∼20-100 MeV, depending on the intensity of the magnetic field in the WCR. The latter can be in the range ∼20-1500 mG. Conclusions. Our model is able to reproduce the observed radio emission, and predicts that the non-thermal radiation from HD 93129A will increase in the near future. With instruments such as NuSTAR, Fermi, and CTA, it will be possible to constrain the relativistic particle content of the source, and other parameters such as the magnetic field strength in the WCR which, in turn, can be used to obtain upper-limits of the magnetic field on the surface of the very massive stars, thereby inferring whether magnetic field amplification is taking place in the particle acceleration region.

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“…gov, and the CTA one from Takahashi et al (2013). , and p-p (green); the filled red curve is the total emission.…”

Section: Synthetic Mapsmentioning

confidence: 99%

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

Palacio

Bosch‐Ramon

Romero

et al. 2016

A&A

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“…3). The sensitivity of e-ASTROGAM will reveal the transition from [129]). The Fermi/LAT sensitivity is for a high Galactic latitude source in 10 years of observation in survey mode.…”

Section: Science Casementioning

confidence: 99%

The e-ASTROGAM mission

et al. 2017

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e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV -the lower energy limit can be pushed to energies as low as 150 keV, albeit with rapidly degrading angular resolution, for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and the promise of eLISA.

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“…The synchrotron X-ray emission is produced by 10-100 TeV electrons, while the TeV γ-rays are produced either through π 0 -decay (the so-called hadronic scenario) or IC (the leptonic scenario); the origin of the TeV γ-ray FIGURE 1. Differential sensitivities of X-ray and γ-ray instruments for a point source [9]. Lines for the Chandra, Suzaku, INTEGRAL, and ASTRO-H (HXI and SGD) are the 3σ sensitivity curves for 100 ks exposures.…”

Section: Introductionmentioning

confidence: 99%

Nonthermal X-ray astronomy

Uchiyama¹

2012

AIP Conference Proceedings

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We provide a concise review of X-ray observations of synchrotron and inverse Compton radiation from relativistic electrons in cosmic sources, in the context of synergies between X-ray and γ-ray astronomy. Particular emphasis is placed on the cases of supernova remnants, pulsar wind nebulae, and relativistic jets of quasars. We discuss that imaging spectroscopy of synchrotron X-ray emission plays key roles in studying acceleration and transport of high-energy electrons, as well as in probing the magnetic field through a comparison with TeV γ-ray data. To demonstrate some prospects for future X-ray observations, we showcase the scientific capabilities of the next major X-ray observatory, ASTRO-H, which is a joint JAXA-NASA mission to be launched in 2014.

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Multiwavelength Astronomy and CTA: X-rays

Cited by 26 publications

References 132 publications

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

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

The e-ASTROGAM mission

Nonthermal X-ray astronomy

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