Interacción entre los radio-jets y el material interestelar en radiogalaxias

En este trabajo se estudian los sistemas nebulares (gas ionizado) localizados en las regiones más externas de potentes radiogalaxias y conocidos como Regiones Extendidas con Emisión de Líneas (EELR). Fueron descubiertos en forma sistemática mediante observaciones con el Telescopio Espacial Hubble (HST). Las propiedades que las definen desde su propio nombre son las grandes distancias hasta las cuales es posible localizarlas, superando el alcance de la componente estelar en las mismas imágenes del HST, y el tipo de líneas de emisión que componen su espectro. El estudio consta de la determinación del proceso de ionización dominante en la zona, mediante la comparación de los dos principales mecanismos posibles: la ionización de las nebulosas por parte del campo de radiación emitido por la fuente central, y la ionización por ondas de choque radiativas, desencadenadas por la interacción de la radiofuente, en particular, sus jets, con el medio que atraviesa (sólo en un objeto los procesos de choque estarían desencadenados por otro mecanismo). Los análisis requieren de la evaluación de las propiedades físicas del sistema gaseoso, ya sea la profundidad óptica, la distancia que las separa de la fuente puntual, el comportamiento espacial de la emisión o sus características cinemáticas, para poder estudiarlas bajo las hipótesis de cada modelo. El rol que desempeñe el núcleo activo nunca será despreciable, sin embargo, el interés por el estudio sistemático de la interacción entre los jets y el material interestelar radica en que este mecanismo podría explicar el estado de ionización de las EELR de la mano de su estado cinemático. La técnica empleada fue la espectroscopía óptica de ranura larga (long-slit). Todos los espectros nebulares se tomaron especialmente para el desarrollo de esta Tesis con el instrumento GMOS del Telescopio Gemini Norte (TGN). La excelente calidad de los datos obtenidos permitió completar las tres líneas principales de la investigación: el análisis espectroscópico, el comportamiento espacial de la emisión y la cinemática de la región. El objetivo principal fue obtener una explicación tan global como fuera posible sobre las características multibanda de la emisión, con especial énfasis en la relación espacial que pudiera haber entre la emisión y la cinemática en las distintas bandas del espectro, y en la relación de alineamiento entre las estructuras en óptico y en radio. Los modelos se analizaron según sus predicciones sobre las estructuras de ionización y con la información contenida en los cocientes de líneas (diagramas de diagóstico). En general, la estructura de ionización no puede resolverse espacialmente en ninguno de los dos escenarios, pero la información contenida en el comportamiento espacial de las líneas de emisión fue determinante para evaluar el dominio de una región sobre otra y, consecuentemente, de un mecanismo de ionización sobre el otro. Se encontraron fuentes donde se puede asegurar el dominio de un mecanismo concreto, y fuentes donde se necesita la contribución de ambos para poder explicar tanto las características espectrales, como la intensidad de la radiación observada. En la mayoría de los objetos analizados (cinco de siete) la EELR está alineada con los radio-jets. Sin embargo, los resultados son compatibles no con la dirección de alineación radio-óptico sino con la información contenida en los campos de velocidades. En los casos donde se puede asegurar que la ionización ocurre predominantemente como consecuencia de procesos de choque, el campo de velocidades siempre muestra importantes indicios de movimientos de perturbación con velocidades altas. En los casos donde domina la fotoionización del campo central, las perturbaciones cinemáticas nunca son significativas.Facultad de Ciencias Astronómicas y Geofísica

The fingerprints of photoionization and shock-ionization in two CSS sources

We investigate the ionization state of the extended emission-line regions (EELRs) around two compact steep-spectrum (CSS) radio galaxies, 3C 268.3 and 3C 303.1, in order to identify the contribution of photoionization and shock-ionization. We perform a new spectroscopical (long-slit) analysis with GMOS/Gemini with the slit oriented in the radio-jet direction, where outflows are known to exist. The [Ne V] λ3426 emission is the most interesting feature of the spectra and the one key to breaking the degeneracy between the models: since this emission-line is more extended than He II, it challenges the ionization structure proposed by any photoionization model, also its intensity relative to H β does not behave as expected with respect to the ionization parameter U in the same scenario. On the contrary, when it is compared to the intensity of [O II] λ3727/H β and all these results are joined, the whole scenario is plausible to be explained as emission coming from the hot, compressed, shocked gas in shock-ionization models. Although the model fitting is strongly sensitive to the chosen line ratios, it argues for the presence of external and strong ionizing fields, such as the precursor field created by the shock or/and the AGN radiation field. In this paper, we show how AGN photoionization and shock-ionization triggered by jet–cloud interaction work together in these EELRs in order to explain the observed trends and line-ratio behaviours in a kinematically acceptable way.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

The fingerprints of photoionization and shock-ionization in two CSS sources

We investigate the ionization state of the extended emission-line regions (EELRs) around two compact steep-spectrum (CSS) radio galaxies, 3C 268.3 and 3C 303.1, in order to identify the contribution of photoionization and shock-ionization. We perform a new spectroscopical (long-slit) analysis with GMOS/Gemini with the slit oriented in the radio-jet direction, where outflows are known to exist. The [Ne V] λ3426 emission is the most interesting feature of the spectra and the one key to breaking the degeneracy between the models: since this emission-line is more extended than He II, it challenges the ionization structure proposed by any photoionization model, also its intensity relative to H β does not behave as expected with respect to the ionization parameter U in the same scenario. On the contrary, when it is compared to the intensity of [O II] λ3727/H β and all these results are joined, the whole scenario is plausible to be explained as emission coming from the hot, compressed, shocked gas in shock-ionization models. Although the model fitting is strongly sensitive to the chosen line ratios, it argues for the presence of external and strong ionizing fields, such as the precursor field created by the shock or/and the AGN radiation field. In this paper, we show how AGN photoionization and shock-ionization triggered by jet–cloud interaction work together in these EELRs in order to explain the observed trends and line-ratio behaviours in a kinematically acceptable way.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Searching for evidence of jet-cloud interaction in radio galaxies : First results for 3C 381

We present results of Gemini spectroscopy and Hubble Space Telescope imaging of the 3C 381 radio galaxy. Possible ionizing mechanisms for the extended emission-line region were studied through state-of-the-art diagnostic analysis employing line ratios. Photoionization from the central engine as well as mixed medium photoionization models fail in reproducing both the strengths and the behaviour of the highest excitation lines, such as [Ne v]λ3424, He ii and [O iii]λ5007, which are measured at very large distances from the active galactic nucleus. Shock-ionization models provide a better fit to the observation. Expanding shocks with velocities higher than 500 km s-1 are capable of reaching the observed intensity ratios for lines with different ionization states and excitation degrees. This model also provides a direct explanation of the mechanical energy input needed to explain the high-velocity line-splitting observed in the velocity field.Facultad de Ciencias Astronómicas y Geofísica

Shock ionization in the extended emission-line region of 3C 305: the last piece of the (optical) puzzle

We present new Gemini spectroscopical data of the extended emission-line region of the 3C 305 radio galaxy in order to achieve a final answer to the long-standing question about the ionizing mechanism. The spectra show strong kinematic disturbances within the most intense line-emitting region. The relative intensities of the emission lines agree with the hypothesis that the gas is shocked during the interaction of powerful radio jets with the ambient medium. The emission from the recombination region acts as a very effective cooling mechanism, which is supported by the presence of a neutral outflow. However, the observed intensity is almost an order of magnitude lower than expected in a pure shock model. So, autoionizing shock models, in low-density and low-abundance regimes, are required in order to account for the observed emission within the region. This scenario also supports the hypothesis that the optical emitting gas and the X-ray plasma are in pressure balance.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Shock ionization in the extended emission-line region of 3C 305: the last piece of the (optical) puzzle

We present new Gemini spectroscopical data of the extended emission-line region of the 3C 305 radio galaxy in order to achieve a final answer to the long-standing question about the ionizing mechanism. The spectra show strong kinematic disturbances within the most intense line-emitting region. The relative intensities of the emission lines agree with the hypothesis that the gas is shocked during the interaction of powerful radio jets with the ambient medium. The emission from the recombination region acts as a very effective cooling mechanism, which is supported by the presence of a neutral outflow. However, the observed intensity is almost an order of magnitude lower than expected in a pure shock model. So, autoionizing shock models, in low-density and low-abundance regimes, are required in order to account for the observed emission within the region. This scenario also supports the hypothesis that the optical emitting gas and the X-ray plasma are in pressure balance.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Searching for evidence of jet-cloud interaction in radio galaxies : First results for 3C 381

We present results of Gemini spectroscopy and Hubble Space Telescope imaging of the 3C 381 radio galaxy. Possible ionizing mechanisms for the extended emission-line region were studied through state-of-the-art diagnostic analysis employing line ratios. Photoionization from the central engine as well as mixed medium photoionization models fail in reproducing both the strengths and the behaviour of the highest excitation lines, such as [Ne v]λ3424, He ii and [O iii]λ5007, which are measured at very large distances from the active galactic nucleus. Shock-ionization models provide a better fit to the observation. Expanding shocks with velocities higher than 500 km s-1 are capable of reaching the observed intensity ratios for lines with different ionization states and excitation degrees. This model also provides a direct explanation of the mechanical energy input needed to explain the high-velocity line-splitting observed in the velocity field.Facultad de Ciencias Astronómicas y Geofísica

Search of Extended Objects in the Southern Sky (SExOSS) using S-PLUS DR1: photometric characterization of extragalactic sources

The SExOSS (Search of Extended Objects in the Southern Sky) project is planning to study alarge sample of extended sources in the southern sky. Using The Southern Photometric Local Universe Survey(S-PLUS) data taken in 12 filters (5 broad + 7 narrow bands), the first step will consist to analyze the photometricrelationships shown using the broandband magnitudes, and through a deeper characterization made from narrowband filters behaviour. Such a characterization could reveal the existence of new photometric relationshipsinvolving one or more of those narrow band magnitudes available in this survey. In the present work, the firstresults obtained are shown, on a sample of extended sources included in the first data release (DR1) of S-PLUS.This first release corresponds to the Stripe-82 sky area previously observed by the Sloan Digital Sky Survey (SDSS).For our analysis, we considered a subsample of objects that had spectra in the SDSS to be able to perform aspectroscopic classification of their internal activity (galaxies with/without star formation, active nuclei, etc.) andthen searching for links between the properties shown in the narrow band photometry. The S-PLUS DR1 hasmore than 3 × 105sources, of which about 3 × 104 have been found to be extended and matched in the SDSS. Wepresent here the results obtained on a subsample selected by considering threshold values for the signtal-to-noiselevel in both the SDSS spectra and the magnitude value in the DR1 database, on which a blind classification ofinternal activity was carried out.Fil: Haack, Rodrigo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Andruchow, Ileana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: López, Iván. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Reynaldi, María Victoria. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Saponara, Juliana. 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: Smith Castelli, Analia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina62º Reunión Anual de la Asociacion Argentina de AstronomiaRosarioArgentinaUniversidad Nacional de RosarioComplejo Astronómico Municipal Galileo Galile

The excitation mechanisms of X-ray oxygen emission-lines

We present the Catalogue of High REsolution Spectra of Obscured Sources (CHRESOS) from the XMM-Newton Science Archive. It comprises soft X-ray emission-lines from C to Si and the Fe 3C and Fe 3G L-shell transitions. Here, we concentrate on the oxygen emission-lines O VII(f) and O VIII Lyα to shed light onto the physical processes with which their formation can be related to: active galactic nucleus vs. star-forming regions. We are analysing the relationships between the oxygen lines and the luminosities of: [OIII]λ5007, [OIV]25.89μm, MIR-12μm, FIR-60μm, FIR-100μm, and hard X-rays continuum bands.Fil: Reynaldi, María Victoria. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Guainazzi, Matteo. Agencia Espacial Europea. European Space Research And Technology Centre.; Países BajosFil: Bianchi, Stefano. Università Roma Tre Iii.; ItaliaFil: Andruchow, Ileana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: García, Federico. Kapteyn Astronomical Institute; Países Bajos. 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: Lopez, Ivan. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Salerno, Nicolás. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaSymposium S359: Galaxy Evolution and Feedback across Different EnvironmentsBento GonçalvesBrasilInternational Astronomical Unio

On the origin of X-ray oxygen emission lines in obscured AGN

We present the Catalogue of High Resolution Spectra of Obscured Sources (CHRESOS) from the XMM-Newton Science Archive. It comprises the emission-line luminosities of H- and He-like transitions from C to Si, and the Fe 3C and Fe 3G L-shell ones. Here, we concentrate on the soft X-ray O VII (f) and O VIII Lyα emission lines to shed light on to the physical processes with which their formation can be related to active galactic nucleus (AGN) versus star-forming regions. We compare their luminosity with that of two other important oxygen key lines [O III] λ5007 Å, in the optical, and [O IV] 25.89 μm, in the infrared (IR). We also test O VII (f) and O VIII Lyα luminosities against that of continuum bands in the IR and hard X-rays, which point to different ionization processes. We probe into those processes by analysing photoionization and collisional ionization model predictions upon our lines. We show that both scenarios can explain the formation and observed intensities of O VII (f) and O VIII Lyα. By analysing the relationships between O VII (f) and O VIII Lyα, and all other observables: [O III] λ5007 Å, [O IV] 25.89 μm emission lines, and mid-infrared (MIR) 12 μm, far-infrared (FIR) 60 and 100 μm, 2-10 and 14-195 keV continuum bands, we conclude that the AGN radiation field is mainly responsible of the soft X-ray oxygen excitation.Fil: Reynaldi, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Guainazzi, Matteo. Agencia Espacial Europea. European Space Research And Technology Centre.; Países BajosFil: Bianchi, S. Universita Degli Studi Roma Treviso; ItaliaFil: Andruchow, Ileana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: García, Federico. Kapteyn Astronomical Institute; Países BajosFil: Salerno, N. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: López, I. E.. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin