Emisión no térmica y aceleración de partículas en jets protoestelares

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2018.Desde los primeros estudios realizados en radiofrecuencias en regiones de formación estelar, la emisión de jets de objetos estelares jóvenes (YSOs, por sus siglas en inglés) ha sido considerada exclusivamente de origen térmico. La presencia de una componente de emisión no térmica en jets protoestelares, constituye un descubrimiento reciente y sin dudas excepcional, que implica la existencia de partículas con velocidades relativistas en interacción con campos magnéticos. Explicar la presencia de tales partículas en estos sistemas, requiere la acción de un mecanismo responsable de incrementar eficientemente su energía cinética. El principal objetivo de esta Tesis es profundizar en la investigación de este interesante tópico. Para ello se estudió la emisión continua en radio de dos YSOs con distinta masa: (1) La fuente triple en radio continuo en Serpens (masa intermedia), el primer YSO para el cual ha sido propuesta la presencia de emisión sincrotrón y que, morfológicamente, puede considerarse el prototipo de jet protoestelar no térmico; (2) El sistema HH 80-81 (alta masa), uno de los jets protoestelares más potentes conocidos, y el único (hasta el momento) en que se ha detectado emisión centimétrica linealmente polarizada, confirmando el origen sincrotrónico de la radiación. En ambos casos, se realizaron estudios para caracterizar la naturaleza de la emisión en radio en distintas regiones del jet. Los resultados fueron analizados en el contexto de aceleración de partículas en choques del jet con el medio ambiente, explorando los posibles escenarios en que éstas podrían ser eficientemente aceleradas a energías relativistas. El estudio de estos objetos fue abordado en un amplio rango de longitudes de onda de radio, mediante el análisis de nuevos datos de alta sensitividad obtenidos con interferómetro Karl G. Jansky Very Large Array (VLA) del National Radio Astronomy Observatory (NRAO).Since the first studies of star formation regions at radio frequencies, the emission of jets powered by young stellar objects (YSOs) has been exclusively considered of thermal origin. The presence of a non thermal component in the radio emission of these jets constitutes a recent discovery with very importan implications, such as the existence of particles with relativistic velocity interacting with magnetic fields. The existence of relativistic particles in these low energy systems requires the action of a mechanism able to efficiently increase their kinetic energy. The main goal of this Thesis is to deepen the study of this interesting topic. For this purpose we studied the radio continuum emission of two representative YSOs having different masses: (1) The triple source in Serpens (intermediate mass), known to be first YSO for which the presence of synchrotron radiation has been proposed, and morphologically considered as a prototype of non-thermal jets; (2) The system HH 80-81 (high mass), being one of the most powerful protostellar jets known, and the only one (to date) for which linearly polarized centimeter emission has been detected, thus confirming the synchrotronic origin of the radiation. In both cases, studies were conducted to characterize the nature of the radio emission in different regions of the jet. The results were analyzed in the context of particle acceleration in the shocks of the jet with the environment, exploring possible scenarios to accelerate particles up to relativistic energies. We addressed the study of these objects through the analysis of new high sensitivity data obtained with the Karl G. Jansky Very Large Array (VLA) interferometer from the National Radio Astronomy Observatory (NRAO), in a wide range of radio wavelengths

Particle acceleration in the Herbig–Haro objects HH 80 and HH 81

We present an analysis of radio (Karl G. Jansky Very Large Array (VLA)), optical (HST), and X-ray (Chandra and XMM-Newton) observations and archival data of the Herbig-Haro objects HH 80 and HH 81 in the context of jet-cloud interactions. Our radio images are the highest angular resolution to date of these objects, allowing to spatially resolve the knots and compare the regions emitting in the different spectral ranges. We found that soft X-ray thermal emission is located ahead of the non-thermal radio peak. This result is consistent with a radiative forward shock that heats the shocked gas up to 106K, and an adiabatic reverse shock able to accelerate particles and produce synchrotron radiation detectable at radio frequencies. These high angular resolution radio images also reveal a bow shock structure in the case of HH 80N, being the first time this morphology is detected in a Herbig-Haro object at these frequencies.Fil: Rodríguez Kamenetzky, Adriana Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Carrasco Gonzalez, Carlos Eugenio. Universidad Nacional Autónoma de México. Instituto de Radioastronomía y Astrofísica; MéxicoFil: González Martín, Omaira. Universidad Nacional Autónoma de México. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Araudo, Anabella Teresa. Czech Academy of Sciences; República ChecaFil: Rodríguez, Luis Felipe. Universidad Nacional Autónoma de México. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Vig, Sarita. Indian Institute of Space Science and Technology. Department of Earth and Space Science; IndiaFil: Hofner, Peter. New Mexico Tech. Physics Department; Estados Unido

Investigating particle acceleration in Protostellar Jets: The triple radio continuum source in serpens

While most protostellar jets present free-free emission at radio wavelengths, synchrotron emission has also been proposed to be present in a handful of these objects. The presence of nonthermal emission has been inferred by negative spectral indices at centimeter wavelengths. In one case (the HH 80-81 jet arising from a massive protostar), its synchrotron nature was confirmed by the detection of linearly polarized radio emission. One of the main consequences of these results is that synchrotron emission implies the presence of relativistic particles among the nonrelativistic material of these jets. Therefore, an acceleration mechanism should be taking place. The most probable scenario is that particles are accelerated when the jets strongly impact against the dense envelope surrounding the protostar. Here we present an analysis of radio observations obtained with the Very Large Array of the triple radio source in the Serpens star-forming region. This object is known to be a radio jet arising from an intermediate-mass protostar. It is also one of the first protostellar jets where the presence of nonthermal emission was proposed. We analyze the dynamics of the jet and the nature of the emission and discuss these issues in the context of the physical parameters of the jet and the particle acceleration phenomenon.Fil: Rodríguez Kamenetzky, Adriana Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Carrasco Gonzalez, Carlos Eugenio. Universidad Nacional Autónoma de México; MéxicoFil: Araudo, Anabella Teresa. University of Oxford. Department of Physics; Reino Unido. 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: Torrelles, Jose M.. Universidad de Barcelona; EspañaFil: Anglada, Guillem. Instituto de Astrofisica Andalucia; EspañaFil: Marti, Josep. Universidad de Jaén; EspañaFil: Luis Felipe Rodriguez. Universidad Nacional Autónoma de México; MéxicoFil: Valotto, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

Nonthermal emission and particle acceleration in protostellar jets

The presence of non thermal emission detected at radio frequencies in some protostellar jets, constitutes a remarkable discovery with very imporant implications: (1) these low energy systems should be able to accelerate particles up to relativistic energies; (2) when detected, polarized radio emission allow to study magnetic fields with techniques usualy applied to relativistic jets.Here I summarize the main results obtained during my PhD research, devoted to deepen the understanding particle acceleration in protostellar jets, through new JVLA radio observations in wide frequency range These observations allowed to study the jet morphology and the dominant emission nature with unprecedented sensitivity in two representative cases: Te triple source in Serpens, and the HH 80-81 jet.Fil: Rodríguez Kamenetzky, Adriana Raquel. Instituto de Radioastronomía y Astrofísica, Unam; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

Spectroscopic study of the [OIII]λ5007 profile in Seyfert 1 galaxies

The spectra of active galactic nuclei usually exhibit wings in some emission lines, such as [OIII]λλ5007,4959, with these wings generally being blueshifted and related to strong winds and outflows. The aim of this work was to analyse the [OIII] emission lines in broad line Seyfert 1 (BLS1) galaxies in order to detect the presence of wings, and to study the [OIII] line properties and their possible connection with the central engine. In addition, we attempted to compare the black hole mass distribution in both BLS1 galaxies with symmetric and blue-asymmetric [OIII] profiles. For this purpose, we carried out a spectroscopic study of a sample of 45 nearby southern BLS1 galaxies from the 6 Degree Field Galaxy survey. The [OIII] emission lines were well fitted using a single Gaussian function in 23 galaxies, while 22 objects presented a wing component and required a double-Gaussian decomposition. By computing the radial velocity difference between the wing and core centroids (i.e. ∆v), we found 18 galaxies exhibiting blueshifted wings, 2 objects presenting red wings and 2 galaxies showing symmetric wings (∆v=0). Moreover, ∆v was slightly correlated with the black hole mass. In addition, we computed the radial velocity difference of the blue-side full extension of the wing relative to the centroid of the core component through the blue emission parameter, which revealed a correlation with black hole mass, in agreement with previous results reported for narrow line galaxies. Finally, in our sample, similar black hole mass distributions were observed in both BLS1 galaxies with symmetric and blueshifted asymmetric [OIII] profiles.Fil: Schmidt, Eduardo Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Baravalle, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Rodríguez Kamenetzky, Adriana Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Universidad Nacional Autónoma de México; Méxic

The Highly Collimated Radio Jet of HH 80-81: Structure and Nonthermal Emission

Radio emission from protostellar jets is usually dominated by free-free emission from thermal electrons. However, in some cases, it has been proposed that nonthermal emission could also be present. This additional contribution from nonthermal emission has been inferred through negative spectral indices at centimeter wavelengths in some regions of the radio jets. In the case of HH 80-81, one of the most powerful protostellar jets known, linearly polarized emission has also been detected, revealing that the nonthermal emission is of synchrotron nature from a population of relativistic particles in the jet. This result implies that an acceleration mechanism should be taking place in some parts of the jet. Here, we present new high sensitivity and high angular resolution radio observations at several wavelengths (in the 3-20 cm range) of the HH 80-81 radio jet. These new observations represent an improvement in sensitivity and angular resolution by a factor of ∼10 with respect to previous observations. This allows us to resolve the morphology of the radio jet and to study the different emission mechanisms involved through spectral index maps. We conclude that synchrotron emission in this jet arises from an extended component detected at low frequencies and from the termination points of the jet, where strong shocks against the ambient medium can produce efficient particle acceleration.Fil: Rodríguez Kamenetzky, Adriana Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Carrasco Gonzalez, Carlos Eugenio. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Araudo, Anabella Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Astronomical Institute of the Academy of Sciences; República ChecaFil: 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; ArgentinaFil: Torrelles, José M.. Consejo Superior de Investigaciones Científicas; EspañaFil: Rodríguez, Luis F.. Instituto de Radioastronomía y Astrofísica; MéxicoFil: Anglada, Guillem. Consejo Superior de Investigaciones Científicas; EspañaFil: Martí, Josep. Universidad de Jaén; EspañaFil: Perucho, Manel. Universidad de Valencia; EspañaFil: Valotto, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin