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Register a new userGamma-ray emission from Wolf-Rayet stars interacting with AGN jets
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Dense populations of stars surround the nuclear regions of galaxies. In this work, we study the interaction of a WR star with relativistic jets in active galactic nuclei. A bow-shaped double-shock structure will form as a consequence of the interaction of the jet and the wind of the star. Particles can be accelerated up to relativistic energies in these shocks and emit high-energy radiation. We compute the produced gamma-ray emission obtaining that this radiation may be significant. This emission is expected to be particularly relevant for nearby non-blazar sources.
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Dense populations of stars surround the nuclear regions of galaxies. In active galactic nuclei, these stars can interact with the relativistic jets launched by the supermasive black hole. In this work, we study the interaction of early-type stars with relativistic jets in active galactic nuclei. A bow-shaped double-shock structure is formed as a consequence of the interaction of the jet and the stellar wind of each early-type star. Particles can be accelerated up to relativistic energies in these shocks and emit high-energy radiation. We compute, considering different stellar densities of the galactic core, the gamma-ray emission produced by non-thermal radiative processes. This radiation may be significant in some cases, and its detection might yield valuable information on the properties of the stellar population in the galaxy nucleus, as well as on the relativistic jet. This emission is expected to be particularly relevant for nearby non-blazar sources.
We study the interaction of early-type stars with the jets of active galactic nuclei. A bow-shock will form as a consequence of the interaction of the jet with the winds of stars and particles can be accelerated up to relativistic energies in these shocks. We compute the non-thermal radiation produced by relativistic electrons from radio to gamma-rays. This radiation may be significant, and its detection might yield information on the properties of the stellar population in the galaxy nucleus, as well as on the relativistic jet. This emission is expected to be relevant for nearby non-blazar sources.
Using a code that employs a self-consistent method for computing the effects of photoionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive Wolf-Rayet (W-R) stars. Our algorithm incorporates a simplified model of the photo-ionization source, computes the fractional ionization of hydrogen due to the photoionizing flux and recombination, and determines self-consistently the energy balance due to ionization, photo-heating and radiative cooling. We take into account changes in stellar properties and mass-loss over the stars evolution. Our multi-dimensional simulations clearly reveal the presence of strong ionization front instabilities. Using various X-ray emission models, and abundances consistent with those derived for W-R nebulae, we compute the X-ray flux and spectra from our wind bubble models. We show the evolution of the X-ray spectral features with time over the evolution of the star, taking the absorption of the X-rays by the ionized bubble into account. Our simulated X-ray spectra compare reasonably well with observed spectra of Wolf-Rayet bubbles. They suggest that X-ray nebulae around massive stars may not be easily detectable, consistent with observations.
Different theoretical models predict VHE gamma-ray emission to arise in tight binary star systems (high mass-loss and high wind speeds), which has not been confirmed experimentally so far. Here we present the first bounds on the VHE emission from two isolated Wolf-Rayet star binaries, WR147 and WR146, obtained with the MAGIC telescope.
The Wolf-Rayet (WR) bubble S 308 around the WR star HD 50896 is one of the only two WR bubbles known to possess X-ray emission. We present XMM-Newton observations of three fields of this WR bubble that, in conjunction with an existing observation of its Northwest quadrant, map most of the nebula. The X-ray emission from S 308 displays a limb-brightened morphology, with a central cavity ~22 arcmin in size and a shell thickness of ~8 arcmin. This X-ray shell is confined by the optical shell of ionized material. The spectrum is dominated by the He-like triplets of NIV at 0.43 keV and OVII at 0.57 keV, and declines towards high energies, with a faint tail up to 1 keV. This spectrum can be described by a two-temperature optically thin plasma emission model (T1 ~ 1.1x10^6 K, T2 ~ 13x10^6 K), with a total X-ray luminosity ~2x10^33 erg/s at the assumed distance of 1.5 kpc.
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