Matias M. Reynoso

A lepto-hadronic model for high-energy emission from FR I radiogalaxies

Context. The well known radiogalaxy Cen A has been recently detected as a source of very high energy (VHE) γ-rays by the HESS experiment just before Fermi/LAT detected it at high energies (HE). The detection, together with that of M 87, established radiogalaxies as VHE γ-ray emitters. Aims. The aim of this work is to present a lepto-hadronic model for the VHE emission from the relativistic jets in FR I radiogalaxies. Methods. We consider that protons and electrons are accelerated in a compact region near the base of the jet, and they cool emitting multi wavelength radiation as propagating along the jet. The proton and electron distributions are obtained through steady-state transport equation taking into account acceleration, radiative and non-radiative cooling processes, as well as particle transport by convection. Results. Considering the effects of photon absorption at different wavelengths, we calculate the radiation emitted by the primary protons and electrons, as well as the contribution of secondaries particles (e ± , π sa ndμs). The expected high-energy neutrino signal is also obtained and the possibility of detections with KM3NeT and IceCube is discussed. Conclusions. The spectral energy distribution obtained in our model with an appropriate set of parameters for an extended emission zone can account for much of the observed spectra for both AGNs.

Precession of neutrino-cooled accretion disks in gamma-ray burst engines

Aims. We study the precession of accretion disks in the context of gamma-ray burst inner engines. Methods. With an accretion disk model that allows for neutrino cooling, we evaluate the possible periods of disk precession and nutation due to the Lense-Thirring effect. Results. Assuming jet ejection perpendicular to the disk midplane and a typical intrinsic time dependence for the burst, we find possible gamma-ray light curves with a temporal microstructure similar to what is observed in some subsamples. Conclusions. We conclude that the precession and nutation of a neutrino-cooled accretion disk in the burst engine might be responsible for some events, especially those with a slow rise and a fast decay.

Gravitational radiation from precessing accretion disks in gamma-ray bursts

We study the precession of accretion disks in the context of gamma-ray burst inner engines. Our aim is to quantitatively estimate the characteristics of gravitational waves produced by the precession of the transient accretion disk in gamma-ray bursts. We evaluate the possible periods of disk precession caused by the Lense-Thirring effect using an accretion disk model that allows for neutrino cooling. Assuming jet ejection perpendicular to the disk plane and a typical intrinsic time-dependence for the burst, we find gamma-ray light curves that have a temporal microstructure similar to that observed in some reported events. The parameters obtained for the precession are then used to evaluate the production of gravitational waves. We find that the precession of accretion disks of outer radius smaller than

Production of gamma rays and neutrinos in the dark jets of the microquasar SS433

10^8

On neutrino absorption tomography of the Earth

cm and accretion rates above 1 solar mass per second could be detected by Advanced LIGO if they occur at distances of less than 100 Mpc. We conclude that the precession of a neutrino-cooled accretion disk in long gamma-ray bursts can be probed by gravitational wave astronomy. Precession of the disks in short gamma-ray events is undetectable with the current technology.

Gamma-ray absorption in the microquasar SS433

We study the spectral energy distribution of gamma rays and neutrinos in the precessing microquasar SS433 as a result of pp interactions within its dark jets. Gamma-ray absorption due to interactions with matter of the extended disc and of the star is found to be important, as well as absorption caused by the ultraviolet and mid-infrared radiation from the equatorial envelopment. We analyse the range of precessional phases for which this attenuation is at a minimum and the chances for detection of a gamma-ray signal are enhanced. The power of relativistic protons in the jets, a free parameter of the model, is constrained by HEGRA data. This imposes limits on the gamma-ray fluxes to be detected with instruments such as GLAST, VERITAS and MAGIC II. A future detection of high-energy neutrinos with cubic kilometre telescopes such as IceCube would also yield important information about acceleration mechanisms that may take place in the dark jets. Overall, the determination of the ratio of gamma-ray to neutrino flux will result in a key observational tool to clarify the physics of heavy jets.

A two-component model for the high-energy variability of blazars - Application to PKS 2155-304

Abstract We study the passage of UHE neutrinos through the Earth in order to perform an absorption tomography of its inner structure. The aim of this work is to study the extraction methods of the Earths density, in this conditions, we do not need to implement a realistic Monte Carlo simulation, as we are only interested in comparing the goodness of a standard method [Astropart. Phys. 12 (1999) 193] with the one we propose. The Earths density is reconstructed using the 2-d Radon transform and we compare the density obtained considering neutral current regeneration through the complete transport equation, with the one obtained making use of the effective cross section approximation (standard method). We see that the effective cross section leads in general to inaccurate results, especially for flat initial neutrino fluxes, while the full transport equation method works regardless of the initial flux. Finally, an error propagation analysis made for different uncertainties in the surviving neutrino flux shows that the recovered density presents a percentage uncertainty less than two times the uncertainty in the flux.

New physics with IceCube

We discuss the gamma-ray absorption in the inner region of the microquasar SS433. Our investigation includes several contributions to the opacity of this system. They result from the ambient fields generated by the primary star, possibly an A-type supergiant, and a very extended disk around the black hole. Besides the sharp and dramatic absorption effect that occurs every time the star crosses the emission zone, we find in the UV photon field from the extended disk an important source of absorption for very high energy gamma-rays. This results in periodic gamma-ray observational signatures.

A two-zone approach to neutrino production in gamma-ray bursts

Aims. We study the production of very-high-energy emission in blazars as a superposition of a steady component from a baryonic jet and a time-dependent contribution from an inner e − e + beam launched by the black hole. Methods. Both primary relativistic electrons and protons are injected in the jet, and the particle distributions along it are found by solving a one-dimensional transport equation that accounts for convection and cooling. The short-timescale variability of the emission is explained by local pair injections in turbulent regions of the inner beam. Results. For illustration, we apply the model to the case of PKS 2155-304, reproducing a quiescent state of emission with inverse Compton and synchrotron radiation from primary electrons, as well as proton-proton interactions in the jet. The latter also yield an accompanying neutrino flux that could be observed with a new generation km-scale detector in the northern hemisphere such as KM3NeT.

A MODEL FOR THE HIGH-ENERGY EMISSION FROM BLAZARS

IceCube, a cubic kilometer neutrino telescope, will be capable of probing neutrino-nucleon interactions in the ultrahigh energy regime, far beyond the energies reached by colliders. In this article we introduce a new observable that combines several advantages; it only makes use of the upward-going neutrino flux, so that the Earth filters the atmospheric muons, and it is only weakly dependent on the initial astrophysical flux uncertainties.