Astrophysical jets

The production of jets is a characteristic common to different astrophysical accreting objects at all scales, from long gamma-ray bursts to galactic binaries. Aside from certain phenomenology specific to each type of source, the physical processes underlying the formation and propagation of the jets is believed to be the same. I present some general ideas on the dynamics and energetics of relativistic jets, discussing the mechanisms of ejection, acceleration, and collimation of the outflows. I also focus on the radiative aspects of jets, reviewing the most relevant mechanisms of non-thermal emission with special emphasis in the high-energy regime.Fil: Vila, Gabriela Soledad. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina1st Argentinian-Brazilian Meeting on Gravitation, Relativistic Astrophysics and Cosmology (GrACo)Foz de IguazúBrasilGRAC

High-energy emission from accreting black holes with high-mass donor stars

We present an analysis of the interactions of a distribution of relativistic protons under the typical conditions of the corona surrounding an accreting black hole. The model is applied to a concrete binary system with a high-mass donor star: the classical source Cygnus X-1Fil: Vila, Gabriela Soledad. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Romero, Gustavo Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A leptonic/hadronic jet model for the low-mass microquasar XTE J1118+480

We present a one–zone jet model that fits the data from simultaneous broadband radio-to-X-rays observations of XTE J1118+480. We calculate the radiative contribution to the non-thermal spectrum of both relativistic electrons and protons, as well as that from secondary muons, charged pions and electron-positron pairs produced at high-energy hadronic interactions. The distributions in energy of all the particle species are obtained taking into account the energy losses, injection, decay and escape from the emission region. We also include absorption effects on the emission spectrum due to photon-photon annihilation. Finally, we discuss the detectability of XTE J1118+480 at high energies with the present instruments according to the predictions of our model for the gamma-ray band.Fil: Vila, Gabriela Soledad. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaIAU Symposium 275: Jets at all ScalesBuenos AiresArgentinaInternational Astronomical Unio

Leptonic/hadronic models for electromagnetic emission in microquasars: The case of GX 339-4

We present a general self-consistent lepto/hadronic jet model for the non-thermal electromagnetic emission of microquasars. The model is applied to the low-mass microquasar (LMMQ) GX 339-4 and predicts its high-energy features. We assume that both leptons and hadrons are accelerated up to relativistic energies by diffusive shock acceleration and calculate their contribution to the electromagnetic spectrum through all main radiative processes. The radiative contribution of secondary particles (pions, muons and electron-positron pairs) is included. We use a set of simultaneous observations in radio and X-rays to constrain the model parameters and find the best fit to the data. We obtain different spectral energy distributions that can explain the observations, and make predictions for the high-energy emission. Observations with gamma-ray instruments like Fermi can be used to test the model and determine the proton content of the jets. Finally, we estimate the positron injection in the surrounding medium. Our findings support the suggested association between LMMQs and the observed distribution of the 511 keV line flux observed by INTEGRAL.Facultad de Ciencias Astronómicas y Geofísica

High-energy emission from accreting black holes with high-mass donor stars

We present an analysis of the interactions of a distribution of relativistic protons under the typical conditions of the corona surrounding an accreting black hole. The model is applied to a concrete binary system with a high-mass donor star: the classical source Cygnus X-1Facultad de Ciencias Astronómicas y Geofísica

Un videojuego de contabilidad y su eficacia en cuanto a sus atributos, motivación y resultados de aprendizaje

El objetivo del presente trabajo es valorar la efectividad de un videojuego de contabilidad en relación a sus atributos, motivación y resultados de aprendizaje. Los resultados muestran que, en relación a los atributos, la mayoría fueron evaluados favorablemente,destacando los relacionados con diversión, adicción y la provisión de información clara sobre los objetivos mientras que los menos valorados fueron los relacionados con la retroalimentación. En cuanto a la motivación, los resultados muestran que los estudiantes perciben la actividad como motivadora, sobre todo en cuanto a disfrute con el juego y sensación de éxito. Y, en cuanto a los objetivos de aprendizaje, los resultados dan sus valores más altos demostrando que los participantes perciben que aprenden y que consiguen sus objetivos

The proton low-mass microquasar: High-energy emission

Context. A population of unidentified gamma-ray sources is forming a structure resembling a halo around the Galactic center. These sources are highly variable, and hence they should be associated with compact objects. Microquasars are objects undergoing accretion with relativistic jets; if such an object has a low-mass, evolved, donor star, it might be found in the Galactic halo. If these low-mass microquasars can generate detectable gamma-ray emission, then they are natural candidates to account for the halo high-energy sources. Aims. We aim to construct models for high-energy emission of low-mass microquasars, which could produce a significant luminosity in the gamma-ray domain. Methods. We consider that a significant fraction of the relativistic particles in the jets of low-mass microquasars are protons and then we study the production of high-energy emission through proton synchrotron radiation and photopion production. Photopair production and leptonic processes are considered as well. We compute a number of specific models with different parameters to explore the possibilities of this scenario. Results. We find that important luminosities, in the range of 1034-1037 erg s-1, can be achieved by proton synchrotron radiation in the Gamma-Ray Large Area Space Telescope (GLAST) energy range, and lower, but still significant luminosities at higher energies for some models. Conclusions. We conclude that the proton microquasar model offers a very interesting alternative to account for the halo gamma-ray sources and presents a variety of predictions that might be tested in the near future by instruments like GLAST, the High-Energy Stereoscopic System II (HESS II), the Major Atmospheric Gamma-ray Imaging Cherenkov telescope II (MAGIC II), and neutrino telescopes like IceCube.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

A leptonic/hadronic jet model for the low-mass microquasar XTE J1118+480

We present a one-zone jet model that fits the data from simultaneous broadband radio-to-X-rays observations of XTE J1118+480. We calculate the radiative contribution to the non-thermal spectrum of both relativistic electrons and protons, as well as that from secondary muons, charged pions and electron-positron pairs produced at high-energy hadronic interactions. The distributions in energy of all the particle species are obtained taking into account the energy losses, injection, decay and escape from the emission region.We also include absorption effects on the emission spectrum due to photon-photon annihilation. Finally, we discuss the detectability of XTE J1118+480 at high energies with the present instruments according to the predictions of our model for the gamma-ray band.Facultad de Ciencias Astronómicas y Geofísica

Supermassive black hole binaries at high energies

An accretion disk around a supermassive black hole may be strongly perturbed by the presence of a secondary black hole. Recent simulations have shown that, under certain conditions, the tidal torques exerted by the secondary black hole may open an annular gap in the disk. In this regime, matter "overflows" across the secondary's orbit to accrete onto the primary and may feed a pair of relativistic jets. In this work we study the radiative properties of a binary system of supermassive black holes, assuming that a relativistic jet is launched from the primary and the migration of the secondary across the disk proceeds in the "overflowing" regime. The modified radiative spectrum of the disk is calculated accounting for strong gravitational effects in the innermost region. The jet emits non-thermal radiation all along the electromagnetic spectrum by interaction of locally accelerated electrons with the jet's magnetic field and internal and external radiation. In particular, we investigate whether the interaction of the relativistic electrons with the photons emitted by the accretion disk induces any signature in the spectral energy distribution of the jet that may reveal the presence of the secondary black hole.Fil: Romero, Gustavo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto Argentino de Radioastronomia (i); ArgentinaFil: Pérez, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto Argentino de Radioastronomia (i); ArgentinaFil: Vila, Gabriela Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto Argentino de Radioastronomia (i); Argentin