A multi-wavelength study of the interstellar medium in active galactic nuclei at cosmic noon

One of the most remarkable discoveries of the last two decades is that all massive galaxies host a supermassive black hole (SMBH) at their center, which has gone through an active phase of growth known as active galactic nucleus (AGN). Although galaxy evolution models need AGN feedback to reproduce the observed properties of galaxies, direct observational evidence for the mechanisms through which SMBHs and galaxies co-evolve has still to be proven. The peak epoch of galaxy assembly and SMBH growth, the so-called "cosmic noon" (1<z<3), represents a key laboratory to understand how the connection between AGN and their host galaxies was established. In this thesis, I presented observational studies of the interstellar medium (ISM) of X-ray selected AGN at cosmic noon. The gas content is directly linked to the evolution of the AGN and its host galaxy. Indeed, it feeds both the formation of new stars in the galaxy and the growth of the central SMBH. The gas in the host along our line of sight may also have a pivotal role in obscuring the central nuclear source. Finally, the kinematics and composition of the gas could be affected by the energy released by the central AGN, through the so-called AGN feedback. To achieve a comprehensive study of the ISM, I adopted a multi-wavelength approach and exploited a variety of data, from the X-ray to the radio regime, by using techniques such as broad-band spectral energy distribution (SED) fitting, X-ray spectral analysis and submm spectroscopy. I first investigated whether the obscuration observed in the X-ray spectra of AGN can be produced by the ISM of the host galaxy. For a sample of far-IR detected AGN at z>2.5 I found that the total hydrogen column density along the line of sight, measured in the X-ray band, is comparable to the column density associated with the ISM of the host, derived through SED-fitting analysis and assuming galaxy sizes. Therefore, the ISM of the host appears to be capable of providing significant absorption on kpc scales. Such absorption adds to (or even replaces) that produced on pc scales by any circumnuclear material, challenging the view of the obscured/unobscured AGN dichotomy as due to inclination effects only. Then, I conducted two complementary studies to probe the ionized and molecular phases of the ISM in a blindly-selected sample of AGN at z~2 that covers a wide range in luminosities. Such studies are necessary to properly constrain the impact of AGN feedback on galaxy evolution. The first, called SUPER, traces ionized outflows through the [OIII] line by using high-resolution spatially-resolved integral field spectroscopic observations (SINFONI). In this work I laid the foundations of the survey, by performing a multi-wavelength characterization of AGN and host galaxy properties, and showed how comparing insights from different techniques/observations is crucial to confirm and provide extra confidence in SED-fitting as well as spectroscopic results. These multi-wavelength properties will then be connected with those of the outflows as traced by SINFONI. The second study used a set of ALMA observations of the CO(J=3-2) transition, to carry out a comparison of the CO properties of AGN with those of a control sample of inactive galaxies matched in redshift, stellar mass and star-formation rate. I found that the AGN sample appears to be underluminous in CO with respect to the control sample and the difference is especially significant at high masses, log(Mstar) > 11. These observations demonstrated that the AGN may have an effect on the ISM of the hosts, although the exact mechanisms in place require further observations to be understood. These projects set the scene for future investigations, which will significantly improve our understanding of the role of AGN in galaxy evolution

Heavily obscured AGN: an ideal laboratory to study the early co-evolution of galaxies and black holes

Obscured AGN are a crucial ingredient to understand the full growth history of super massive black holes and the coevolution with their host galaxies, since they constitute the bulk of the BH accretion. In the distant Universe, many of them are hosted by submillimeter galaxies (SMGs), characterized by a high production of stars and a very fast consumption of gas. Therefore, the analysis of this class of objects is fundamental to investigate the role of the ISM in the early coevolution of galaxies and black holes. We present a multiwavelength study of a sample of six obscured X-ray selected AGN at z>2.5 in the CDF-S, detected in the far-IR/submm bands. We performed the X-ray spectral analysis based on the 7Ms Chandra dataset, which provides the best X-ray spectral information currently available for distant AGN. We were able to place constraints on the obscuring column densities and the intrinsic luminosities of our targets. Moreover, we built up the UV to FIR spectral energy distributions (SEDs) by combining the broad-band photometry from CANDELS and the Herschel catalogs, and analyzed them by means of an SED decomposition technique. Therefore, we derived important physical parameters of both the host galaxy and the AGN. In addition, we obtained, through an empirical calibration, the gas mass in the host galaxy and assessed the galaxy sizes in order to estimate the column density associated with the host ISM. The comparison of the ISM column densities with the values measured from the X-ray spectral analysis pointed out that the contribution of the host ISM to the obscuration of the AGN emission can be substantial, ranging from ~10% up to ~100% of the value derived from the X-ray spectra. The absorption may occur at different physical scales in these sources and, in particular, the medium in the host galaxy is an ingredient that should be taken into account, since it may have a relevant role in driving the early co-evolution of galaxies with their black holes

A multi-wavelength study of the interstellar medium in active galactic nuclei at cosmic noon

One of the most remarkable discoveries of the last two decades is that all massive galaxies host a supermassive black hole (SMBH) at their center, which has gone through an active phase of growth known as active galactic nucleus (AGN). Although galaxy evolution models need AGN feedback to reproduce the observed properties of galaxies, direct observational evidence for the mechanisms through which SMBHs and galaxies co-evolve has still to be proven. The peak epoch of galaxy assembly and SMBH growth, the so-called "cosmic noon" (1<z<3), represents a key laboratory to understand how the connection between AGN and their host galaxies was established. In this thesis, I presented observational studies of the interstellar medium (ISM) of X-ray selected AGN at cosmic noon. The gas content is directly linked to the evolution of the AGN and its host galaxy. Indeed, it feeds both the formation of new stars in the galaxy and the growth of the central SMBH. The gas in the host along our line of sight may also have a pivotal role in obscuring the central nuclear source. Finally, the kinematics and composition of the gas could be affected by the energy released by the central AGN, through the so-called AGN feedback. To achieve a comprehensive study of the ISM, I adopted a multi-wavelength approach and exploited a variety of data, from the X-ray to the radio regime, by using techniques such as broad-band spectral energy distribution (SED) fitting, X-ray spectral analysis and submm spectroscopy. I first investigated whether the obscuration observed in the X-ray spectra of AGN can be produced by the ISM of the host galaxy. For a sample of far-IR detected AGN at z>2.5 I found that the total hydrogen column density along the line of sight, measured in the X-ray band, is comparable to the column density associated with the ISM of the host, derived through SED-fitting analysis and assuming galaxy sizes. Therefore, the ISM of the host appears to be capable of providing significant absorption on kpc scales. Such absorption adds to (or even replaces) that produced on pc scales by any circumnuclear material, challenging the view of the obscured/unobscured AGN dichotomy as due to inclination effects only. Then, I conducted two complementary studies to probe the ionized and molecular phases of the ISM in a blindly-selected sample of AGN at z~2 that covers a wide range in luminosities. Such studies are necessary to properly constrain the impact of AGN feedback on galaxy evolution. The first, called SUPER, traces ionized outflows through the [OIII] line by using high-resolution spatially-resolved integral field spectroscopic observations (SINFONI). In this work I laid the foundations of the survey, by performing a multi-wavelength characterization of AGN and host galaxy properties, and showed how comparing insights from different techniques/observations is crucial to confirm and provide extra confidence in SED-fitting as well as spectroscopic results. These multi-wavelength properties will then be connected with those of the outflows as traced by SINFONI. The second study used a set of ALMA observations of the CO(J=3-2) transition, to carry out a comparison of the CO properties of AGN with those of a control sample of inactive galaxies matched in redshift, stellar mass and star-formation rate. I found that the AGN sample appears to be underluminous in CO with respect to the control sample and the difference is especially significant at high masses, log(Mstar) > 11. These observations demonstrated that the AGN may have an effect on the ISM of the hosts, although the exact mechanisms in place require further observations to be understood. These projects set the scene for future investigations, which will significantly improve our understanding of the role of AGN in galaxy evolution

Miniaturas y composición en el mundo andino: forma, función y agencia

Las imágenes en miniatura se han registrado desde tiempos prehispánicos en la zona andina y en el Noroeste argentino, y son numerosas las evidencias que dan cuenta de la presencia de estos objetos en contexto ritual: fuentes coloniales, registros arqueológicos y relatos etnográficos nos hablan del “uso” de estos objetos en ceremonias domésticas, funerarias o chamánicas. No obstante, no hay sido estudiadas de manera sistemática por la historia del arte ni por la antropología. Esta presentación es parte del proyecto doctoral en el que estudio el uso y agencia de las miniaturas en la Feria de Alasitas, una fiesta del altiplano boliviano que hace más de una década se celebra también en la Ciudad de Buenos Aires. La celebración de Alasitas o Fiesta del Ekeko que se realiza cada 24 de Enero es una de las prácticas culturales que se pusieron en escena en la ciudad de Buenos Aires tras la llegada de inmigrantes bolivianos identificados con las culturas quechua y aymara. El ritual al Ekeko, dios de la abundancia, se realiza desde tiempos ancestrales en la zona del altiplano andino, en la actualidad tiene su epicentro en la ciudad de La Paz y en su versión local se organiza en varios espacios de la CABA. En esta investigación me refiero a la realizada en la wak´a del Parque Avellaneda, por tratarse de un espacio ritual y legitimador de los pueblos originarios en el ámbito urbano.Eje temático 3: Discursos y representaciones acerca de lo regional.Facultad de Bellas Arte

Volatile Composition and Biological Activity of Key Lime Citrus aurantifolia Essential Oil

The essential oil of Citrus aurantifolia (Christm) Swingle fruits (limes) was studied for its potential spasmolytic effects in relation to its chemical composition. The essential oil, extracted by hydrodistillation (HD), was analyzed by GC-FID and GC-MS. The antispasmodic activity was evaluated on isolated rabbit jejunum, aorta and uterus. The results indicated that the essential oil of C aurantifolia possesses important spasmolytic properties, which are likely to be due to its major constituents, limonene (58.4%), β-pinene (15.4%), γ-terpinene (8.5%), and citral (4.4%)

The X-ray emission of z>2.5 active galactic nuclei can be obscured by their host galaxies

We present a multi-wavelength study of seven AGN at spectroscopic redshift >2.5 in the 7 Ms Chandra Deep Field South, selected to have good FIR/sub-mm detections. Our aim is to investigate the possibility that the obscuration observed in the X-rays can be produced by the interstellar medium (ISM) of the host galaxy. Based on the 7 Ms Chandra spectra, we measured obscuring column densities N$_{H, X}$ in excess of 7x10$^{22}$ cm$^{-2}$ and intrinsic X-ray luminosities L$_{X}$>10$^{44}$ erg s$^{-1}$ for our targets, as well as equivalent widths for the Fe K$\alpha$ emission line EW>0.5-1 keV. We built the UV-to-FIR spectral energy distributions by using broad-band photometry from CANDELS and Herschel catalogs. By means of an SED decomposition technique, we derived stellar masses (M$_{*}$~10$^{11}$ Msun), IR luminosities (L$_{IR}$>10$^{12}$ Lsun), star formation rates (SFR~190-1680 Msun yr$^{-1}$) and AGN bolometric luminosities (L$_{bol}$~10$^{46}$ erg s$^{-1}$) for our sample. We used an empirically-calibrated relation between gas masses and FIR/sub-mm luminosities and derived M$_{gas}$~0.8-5.4x10$^{10}$ Msun. High-resolution (0.3-0.7'') ALMA data (when available, CANDELS data otherwise) were used to estimate the galaxy size and hence the volume enclosing most of the ISM under simple geometrical assumptions. These measurements were then combined to derive the column density associated with the ISM of the host, on the order of N$_{H, ISM}$~10$^{23-24}$ cm$^{-2}$. The comparison between the ISM column densities and those measured from the X-ray spectral analysis shows that they are similar. This suggests that, at least at high redshift, significant absorption on kpc scales by the dense ISM in the host likely adds to or substitutes that produced by circumnuclear gas on pc scales (i.e., the torus of unified models). The lack of unobscured AGN among our ISM-rich targets supports this scenario.Comment: 15 pages, 3 figures. Accepted for publication in A&

Miniaturas y composición en el mundo andino: forma, función y agencia

Las imágenes en miniatura se han registrado desde tiempos prehispánicos en la zona andina y en el Noroeste argentino, y son numerosas las evidencias que dan cuenta de la presencia de estos objetos en contexto ritual: fuentes coloniales, registros arqueológicos y relatos etnográficos nos hablan del “uso” de estos objetos en ceremonias domésticas, funerarias o chamánicas. No obstante, no hay sido estudiadas de manera sistemática por la historia del arte ni por la antropología. Esta presentación es parte del proyecto doctoral en el que estudio el uso y agencia de las miniaturas en la Feria de Alasitas, una fiesta del altiplano boliviano que hace más de una década se celebra también en la Ciudad de Buenos Aires. La celebración de Alasitas o Fiesta del Ekeko que se realiza cada 24 de Enero es una de las prácticas culturales que se pusieron en escena en la ciudad de Buenos Aires tras la llegada de inmigrantes bolivianos identificados con las culturas quechua y aymara. El ritual al Ekeko, dios de la abundancia, se realiza desde tiempos ancestrales en la zona del altiplano andino, en la actualidad tiene su epicentro en la ciudad de La Paz y en su versión local se organiza en varios espacios de la CABA. En esta investigación me refiero a la realizada en la wak´a del Parque Avellaneda, por tratarse de un espacio ritual y legitimador de los pueblos originarios en el ámbito urbano.Eje temático 3: Discursos y representaciones acerca de lo regional.Facultad de Bellas Arte

Mapuche terrorista. Pervivencia de estereotipos del siglo XIX en la construcción de la imagen del “indio” como otro/extranjero en la coyuntura de la Argentina actual.

The image of the wild and uncivilized “indian” shaped by traveling artists since the XVI century, was continued by the discourses of the XIX century, that were consolidated with the so-called “generation of ‘80”, for being useful to its objectives of territorial neo-colonization towards The inside of the country. The idea of the Mapuche-foreigner is thus constructed, marginalizing it from the ideology of national identity. The dispute over the land was since then a never-ending battle intensified in the current conjuncture. This article seeks to show that, together with the harassment and persecution of the Mapuche sector, which takes on significance after the death of Santiago Maldonado, those stigmatizations that are now strongly dimensioned and distorted by the mass media are refloated; focusing otherness on the image of the foreign-separatist-terrorist Mapuche, activating discriminatory features well installed in the common sense of a part of the population.La imagen del “indio” salvaje e incivilizado configurada por los artistas viajeros desde el siglo XVI, fue continuada por los discursos del siglo XIX y se consolidaron con la llamada “generación del ´80” por ser útil a sus objetivos de neo-colonización territorial hacia el interior del país. En este artículo se busca evidenciar que, junto al hostigamiento y persecución del sector mapuche, que toma trascendencia a partir de la muerte de Santiago Maldonado, se reflotan aquellas estigmatizaciones ahora fuertemente dimensionadas y distorsionadas por los medios masivos de comunicación; focalizando la otredad en la imagen del mapuche extranjero-separatista-terrorista, activando rasgos discriminatorios. Palabras clave: pueblos originarios - otredad - mapuche - estereotipo.A imagem do selvagem e incivilizado “índio” moldado pelos artistas viajantes desde o século XVI foi continuada pelos discursos do século XIX, que se consolidaram com a chamada “geração dos anos 80”, por ser útil aos seus objetivos de neocolonização territorial em direção ao interior do país. A idéia do estrangeiro Mapuche é assim construída, marginalizando-o da ideologia da identidade nacional. A disputa pela terra foi, desde então, uma batalha interminável intensificada na atual conjuntura. Este artigo procura mostrar que, juntamente com o assédio e a perseguição ao setor mapuche, que assume um significado após a morte de Santiago Maldonado, as estigmatizações que agora são fortemente dimensionadas e distorcidas pelos meios de comunicação de massa são reflutidas; focando a alteridade na imagem do mapuche-separatista- -terrorista estrangeiro, ativando características discriminatórias bem instaladas no senso comum de uma parte da população

On the dust and gas content of high-redshift galaxies hosting obscured AGN in the CDF–S

Submillimeter Galaxies (SMGs) at high redshift are among the best targets to investigate the early evolutionary phases in the lifetime of massive systems, during which large gas reservoirs sustain vigorous star formation and efficiently feed the central, buried Super Massive Black Hole (SMBH), until it enters into luminous Quasar (QSO) phase, quenching the star formation. I present the analysis of new ALMA band 4 (1.8-2.4 mm) data of six obscured QSOs (log NH > 23) hosted by SMGs at redshift > 2.5 in the 7 Ms Chandra Deep Field South (CDF-S), showing their properties in terms of continuum dust emission and high-J CO transitions. Sizes and masses of the galaxies are measured to estimate whether and to which extent the host ISM may contribute to the nuclear absorption, assuming different geometries. The derived column densities suggest that the galaxy ISM can substantially contribute to the AGN obscuration. I also discuss the kinematics and morphology in some of these object, finding that two of the sources present unambiguous features of a rotating system, while a third source is possibly undergoing a merger