Environment of 1 ≤ z ≤ 2 MIR selected obscured and unobscured AGNs in the Extended Chandra Deep Field South

Context. In unified models, different types of active galaxy nuclei (AGN) correspond to a single class of objects, where their observed differences are solely due to the different orientations of the obscuring material around the central inner regions. Recent studies also show that this obscuring material can even extend at galactic scales due to debris from galaxy interactions and/or mergers. In standard unified models the different AGN types are expected to show similar galaxy environments. Aims. We aim to investigate properties and environment of obscured and unobscured AGNs selected from mid-infrared (MIR) bands from the Multiwavelength Survey by Yale-Chile (MUSYC), in order to test the unified model and evolutionary scenarios. Methods. The sample of AGNs was selected from images obtained with the Infrared Array Camera (IRAC) mounted on the Spitzer Space Telescope, based on their MIR colors centered at wavelengths [3.6], [4.5], [5.8] and [8.0] microns. We selected two samples of AGNs with redshifts in the range 1 ≤ z ≤ 2 and rest-frame absolute magnitudes Mv ≤ -21: obscured and unobscured AGNs by means of a simple optical-MIR color cut criterion (R - [4:5] = 3:05.) Results. We find that obscured AGNs are intrinsically optically faint in the R band, suggesting that luminous IR-selected AGNs have a significant dust extinction. From a cross-correlation with several X-ray surveys, we find that the majority of the AGNs in our sample have X-ray luminosities similar to those found in Seyfert-like galaxies. We study the properties of galaxies surrounding these two samples. Neighbouring galaxies located close to (~200 kpc) obscured AGNs tend to have redder colors, compared to the local environment of unobscured AGNs. Results obtained from a KS test show that the two color distributions are different at ~95% confidence level. We find that obscured AGNs are located in denser local galaxy environments compared to the unobscured AGN sample. Conclusions. Our results suggest that AGN obscuration can occur at galactic scales, possibly due to galaxy interactions or mergers, and that the simple unified model based solely on the local torus orientation may not be sufficient to explain all the observations.Fil: Bornancini, Carlos Guillermo. 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: Taormina, Mónica Silvia. Polish Academy of Sciences. Nicolaus Copernicus Astronomical Center; Polonia. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Garcia Lambas, Diego Rodolfo. 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

The distant red galaxy neighbour population of 1 < z < 2 QSOs and optically obscured sources

We study the Distant Red Galaxy (DRG, J-K_s > 2.3) neighbour population of Quasi Stellar Objects (QSOs) selected from the Sloan Digital Sky Survey (SDSS) in the redshift range 1 < z < 2. We perform a similar analysis for optically obscured AGNs (i.e. with a limiting magnitude I > 24) detected in the mid-infrared (24 $\mu$m) with the Spitzer Space Telescope and a mean redshift $z\sim 2.2$ in the Flamingos Extragalactic Survey (FLAMEX). Both QSOs and obscured AGN target samples cover 4.7 deg$^2$ in the same region of the sky. We find a significant difference in the environment of these two target samples. Neighbouring galaxies close to QSOs tend to be bluer than galaxies in optically obscured source environments. We also present results on the cross-correlation function of DRGs around QSOs and optically faint mid-infrared sources. The corresponding correlation length obtained for the QSO sample targets is $r_0$=$5.4\pm1.6$ Mpc h$^{-1}$ and a slope of $\gamma$=$1.94\pm0.10$ . For the optically obscured galaxy sample we find $r_0$=$8.9\pm1.4$ Mpc h$^{-1}$ and a slope of $\gamma$=$2.27\pm0.20$. These results indicate that optically faint obscured sources are located in denser environment of evolved red galaxies compare to QSOs.Comment: Accepted for publication in MNRAS, 9 pages including 5 PostScript figures and 3 table

Cicatrización post-apicectomía: contribución a su estudio

Se evaluó la cicatrización ósea post-apicectomía en 70 casos, de los cuales se realizó un seguimiento clínico-radiográfico, a través de la toma de películas periapicales pre-operatorias, post-operatorias inmediatas y controles post-operatorios a distancia a los 90, 180 y 365 días. se analizaron histopatológicamente los proceso periapicales, y se encontró como patología mas frecuente, granulomas, quistes vírgenes e infectados, colesteatomasy abscesos. Se estableció una evaluación cualitativa a escala arbitraria de 0 (cero) a 4 (cuatro), para la comparación de las imágenes radiográficas a distancia. Se tuvieron en cuenta para su evaluación las siguientes variables: elemento dentario apicectomizado, edad y sexo. Los resultados mostraron un predominio en el número de casos de granulomas (62.89%) y quistes (21.43%) y una mejor cicatrización ósea en quistes, colesteatomas y abscesos, con una escala menor en granulomas y quistes infectados. En elementos dentarios anterosuperiores se observó mejores resultados que en los inferiores y con respecto a edad y sexo no hubo influencia detectable sobre la cicatrización ósea.Ejemplo: Fil: Bornancini, Carlos Alberto. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina

Sistemas de galaxias a altos redshifts /

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física, 2009.En el presente trabajo de tesis se llevó a cabo un estudio sobre el entorno de galaxias en los campos de radiogalaxias a bajos y a altos redshifts, principalmente, y de cuásars (QSOs) y Núcleos Activos Galácticos (AGNs) oscurecidos. Para el análisis de los entornos de radiogalaxias se utilizó una técnica que selecciona objetos de acuerdo a las pendientes pronunciadas (técnica USS) observadas en el espectro en las radiofrecuencias. En el caso de los QSOs y los AGNs oscurecidos se utilizó una técnica fotométrica que permite seleccionar galaxias con la misma distribución de redshifts.Carlos Guillermo Bornancini

Environment and properties of obscured and unobscured active galactic nuclei

Abstract: We analyze the properties of obscured and unobscured active galactic nuclei selected using mid-infrared colors in the redshift range 1 < z < 3. We find that obscured objects are located in a denser local galaxy environment compared to the unobscured sample.We analyze the properties of obscured and unobscured active galactic nuclei selected using mid-infrared colors in the redshift range 1 < z < 3. We find that obscured objects are located in a denser local galaxy environment compared to the unobscured sample.http://adsabs.harvard.edu/abs/2013AAABS...4..153TFil: Taormina, Mónica. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.Fil: Bornancini, Carlos Guillermo. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Bornancini, Carlos Guillermo. Conicet. Instituto de Astronomía Teórica y Experimental; Argentina.Astronomía (incluye Astrofísica y Ciencias del Espacio

Active galactic nuclei at high redshifts: Properties and environment of Type 1 and 2 AGNs

We explore host galaxy properties and environment of a sample of Type 1 and 2 active galactic nuclei (AGN) taken from the COSMOS2015 catalogue (Laigle et al.), within 0.3 ≤ z ≤ 1.1 selected for their emission in X-rays, optical spectra and SED signatures. We find different properties of host galaxies of distinct AGNs: Type 1 AGNs reside in blue, star-forming and less massive host galaxies compared to Type 2. The majority of the AGNs have intermediate X-ray luminosities, 1042 ≤ LX 1044 erg s-1) as those observed in QSOs. Non-parametric morphological analysis show that the majority of Type 1 AGN hosts are elliptical or compact galaxies, while Type 2 AGN host present more scatter, from spirals, irregulars, and elliptical galaxies. The environment of the differentAGNtypes are similar except at small scales (rp < 100 kpc),where Type 2AGNs have more neighbour galaxies than Type 1s. Galaxies located close to Type 2AGNs (~100 kpc) tend to have redder colours, and are more massive compared to the local environment of Type 1s. The observed differences in the environment and host galaxy properties of Type 1 and 2 AGN types show that the obscuration due to the presence of gas and dust may be distributed in larger galactic-scales, possibly originated by galaxy interactions or mergers., after COSMOS2015 catalogue.Fil: Bornancini, Carlos Guillermo. 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: Garcia Lambas, Diego Rodolfo. 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

Imaging and Spectroscopy of Ultra Steep Spectrum Radio Sources

We present a sample of 40 Ultra Steep Spectrum (USS, $\alpha \leq -1.3$, $S_{\nu}\propto \nu^{\alpha}$) radio sources selected from the Westerbork in the Southern Hemisphere (WISH) catalog. The USS sources have been imaged in K--band at the Cerro Tololo Inter-American Observatory (CTIO) and with the Very Large Telescope at Cerro Paranal. We also present VLT, Keck and Willian Herschel Telescope(WHT) optical spectroscopy of 14 targets selection from 4 different USS samples. For 12 sources, we have been able to determine the redshifts, including 4 new radio galaxies at z > 3. We find that most of our USS sources have predominantly small (6'') radio sizes and faint magnitudes (K~18). The mean K-band counterpart magnitude is $\bar{K}$=18.6. The expected redshift distribution estimated using the Hubble K-z diagram has a mean of $\bar{z}_{exp}$$\sim$2.13, which is higher than the predicted redshift obtained for the SUMSS-NVSS sample and the expected redshift obtained in the 6C$^{**}$ survey. The compact USS sample analyzed here may contain a higher fraction of galaxies which are high redshift and/or are heavily obscured by dust. Using the 74, 352 and 1400 MHz flux densities of a sub-sample, we construct a radio colour-colour diagram. We find that all but one of our USS sources have a strong tendency to flatten below 352 MHz. We also find that the highest redshift source from this paper (at z=3.84) does not show evidence for spectral flattening down to 151 MHz. This suggests that very low frequency selected USS samples will likely be more efficient to find high redshift galaxies.Comment: Accepted for publication in MNRAS, 14 pages including 44 PostScript figures and 4 tables. Version with all figures available from http://www.eso.org/~cdebreuc/papers.htm

Host galaxy properties and environment of obscured and unobscured X-ray selected active galactic nuclei in the COSMOS survey

We analyse different photometric and spectroscopic properties of active galactic nuclei (AGNs) and quasars (QSOs) selected by their mid-IR power-law and X-ray emission from the COSMOS survey. We use a set of star-forming galaxies as a control sample to compare with the results. We have considered samples of obscured (HR > −0.2) and unobscured (HR 1044 erg s−1) with 1.4 ≤ z ≤ 2.5. We also study the typical environment of these samples, by assessing neighbouring galaxy number density and neighbour properties such as colour, stellar mass, and star formation rate. We find that the UV/optical and mid-infrared colour distribution of the different AGN types differ significantly. Also, we obtain most of AGNs and QSOs to be more compact when compared to the sample of SF galaxies. In general we find that the stellar mass distribution of the different AGN sample are similar, obtaining only a difference of ΔlogM = 0.3 dex (M☉) between unobscured and obscured QSOs. Obscured and unobscured AGNs and QSOs reside in different local environment at small (rp < 100 kpc) scales. Our results support previous findings where AGN type correlates with environment. These differences and those found in AGN host properties cast out the simplest unified model in which obscuration is purely an orientation effect.Fil: Bornancini, Carlos Guillermo. 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: Garcia Lambas, Diego Rodolfo. 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

Clustering and light profiles of galaxies in the environment of 20 Ultra Steep Spectrum Radio sources

We have analyzed galaxy properties in the neighborhood of 20 Ultra-Steep Spectrum Radio sources (USS) taken from the WISH catalog of De Breuck et al. (2002). Galaxies in these USS fields were identified in deep observations that were carried out in the K'-band using the OSIRIS imager at the CTIO 4m telescope. We find a statistically significant signal of clustering around our sample of USS. The angular extension of the detected USS-galaxy clustering is theta_c~20" corresponding to a spatial scale ~120 h^{-1}kpc, assuming the sources are at z~1 in a Omega_m=0.3, Omega_{\Lambda}=0.7 model universe. These results are in agreement with those obtained by Best (2000) for radio galaxy-galaxy correlation, and Best et al. (2003) for radio-loud AGN-galaxy correlation. We have also analyzed the light distribution of the galaxies by fitting Sersic's law profiles. Our results show no significant dependence of the galaxy shape parameters on the projected distance to the USS.Comment: Accepted for its publication in Astronomical Journal, 9 figure