Building blocks in hierarchical clustering scenarios and their connection with damped Lyα systems

We carried out a comprehensive analysis of the chemical properties of the interstellar medium (ISM) and the stellar population (SP) of current normal galaxies and their progenitors in a hierarchical clustering scenario. We compared the results with observations of damped Lyman- α systems (DLAs) under the hypothesis that, at least, part of the observed DLAs could originate in the building blocks of present-day normal galaxies. We used a hydrodynamical cosmological code which includes star formation and chemical enrichment. Galaxy-like objects are identified at z = 0 and then followed back in time. Random lines of sight (LOS) are drawn through these structures in order to mimic damped Lyman-α systems. We then analysed the chemical properties of the ISM and SP along the LOS. We found that the progenitors of current galaxies in the field with mean L -1 could be the associated DLA galaxies. For these systems we detected a trend for (L/L*) to increase with redshift. We found moderate metallicity evolution for [Zn/H], [Fe/H] and [Si/H]. However, when we applied the observational filter suggested by Boissé et al. (1998) in order to restrict the sample to the observed limits in densities and metallicities, we found mild evolution consistent with observational results that include dust corrections. [Si/Fe] and [S/Fe] show weak α-enhancement in agreement with observations corrected by dust depletion. We found α/Fe in the ISM and SP to have more homogeneous abundances than [Fe/H] and [Zn/H]. In our models, the global metallicity evolution is driven by the high metallicity and high column density simulated DLAs, which have low impact parameters (b 8 M⊙. Our results suggest that geometrical effects could be the mechanism responsible for the non-detectability of high-metallicity and high-column-density DLAs. We found sub-DLAs to map preferentially the outskirts of the simulated DLA galaxies. Hence, they can contribute to the study of the metallicity of the galactic structure as a function of redshift. An analysis of the metallicity content of the ISMs and SPs of the galaxy-like objects as a function of redshift shows the formation of a central stellar mass concentration with nearly solar metallicity at all redshifts while stars in the outer parts of these objects have lower metallicities. The gas content becomes enriched progressively with redshift and at all radii. The abundance properties of the galaxy-like objects and the simulated DLAs are the results of the contribution of type la and II Supernovae and gas infall from the dark matter haloes with a timing settled by their particular evolution history in a hierarchical clustering scenario. Our results suggest that the mild evolution detected in the observations could arise from a conspiracy of all of these processes.Facultad de Ciencias Astronómicas y Geofísica

Chemical Enrichment at High Redshifts: Understanding the Nature of Damped Lyα Systems in Hierarchical Models

We use cosmological hydrodynamical simulations including star formation and metal enrichment to study the evolution of the chemical properties of galaxy-like objects at high redshift in the range 0.25 < z < 2.35 in a hierarchical clustering scenario. We find that as the galactic objects are assembled, their gaseous components exhibit neutral hydrogen column densities with abundances and scatter comparable to those observed in damped Lyα systems (DLAs). The unweighted mean of abundance ratios and least-square linear regressions through the simulated DLAs yield intrinsic metallicity evolution for [Zn/H] and [Fe/H] consistent with results obtained from similar analyses of available observations. Our model statistically reproduces the mild evolution detected in the metallicity of the neutral hydrogen content of the universe, given by mass-weighted means, if observational constraints are considered (as suggested in 1998 by Boissée and co-workers). For the α-elements in the simulated DLAs, we find neither enhancement nor dependence on metallicity. Our results support the hypotheses that DLAs trace a variety of galactic objects with different formation histories and that both Type I and Type II supernovae are contributing to the chemical enrichment of the gas component, at least since z ≈ 2. This study indicates that DLAs could be understood as the building blocks that merged to form current normal galaxies within a hierarchical clustering scenario.Facultad de Ciencias Astronómicas y Geofísica

Chemical Enrichment at High Redshifts: Understanding the Nature of Damped Lyα\alpha Systems in Hierarchical Models

We use cosmological hydrodynamical simulations including star formation and metal enrichment to study the evolution of the chemical properties of galaxy-like objects at high redshift in the range $0.25<z< 2.35$ in a hierarchical clustering scenario. As the galactic objects are assembled we find that their gaseous components exhibit neutral Hydrogen column densities with abundances and scatter comparable to those observed in damped Lyman-$\alpha$ systems (DLAs).The unweighted mean of abundance ratios and least square linear regressions through the simulated DLAs yield intrinsic metallicity evolution for the [Zn/H] and [Fe/H], consistent with results obtained from similar analysis of available observations. Our model statistically reproduces the mild evolution detected in the metallicity of the neutral hydrogen content of the Universe, given by mass-weighted means,if observational constraints are considered (as suggested by Boiss\'ee et al. 1998). For the $\alpha$-elements in the simulated DLAs, we find neither enhancement nor dependence on metallicity. Our results support the hypotheses that DLAs trace a variety of galactic objects with different formation histories and that both SNI and SNII are contributing to the chemical enrichment of the gas component at least since $z \approx 2$. This study indicates that DLAs could be understood as the building blocks that merged to form today normal galaxies within a hierarchical clustering scenario.Comment: 2 Postscript figures.Acepted Ap

Eventos astrofísicos y formación de estructura

Se están estudiando los procesos astrofísicos vinculados a los eventos de explosión de supernova. En particular se analiza la posibilidad que la energía liberada pueda modificar la dinámica local en un esquema jerárquico de formación de estructura como el modelo Coid Dark Matter. Además, se está trabajando en la elaboración de un programa de cómputos basado en el esquema particle - mesh y que permita un tratamiento adecuado de las interacciones partícula - partícula en escalas menores que la resolución del potencial de la red. Esto permitiría un cómputo mas preciso de estos modelos.Asociación Argentina de Astronomí

Antifungal, phyto, cyto, genotoxic and lipophilic properties of three complexes of sulfadimethoxine (HSDM) with Ag(I). Synthesis and characterization of [Ag3SDM(SCN)2]·H2O and [Ag2(SDM)2o-phenanthroline]·H2O

Fungal infections are still a major problem. Some limitations of current antifungals (toxicity, fungal resistance) require the search for new drugs. The interest in metal–sulfanilamide derivatives was stimulated by the successful introduction of a silver-sulfadiazine complex, yet in current use, to prevent microbial infections during burn treatment of both humans and animals. Sulfadimethoxine (HSDM) is used in medicine, most frequently veterinary, to treat many infections, such as respiratory, urinary, etc. In this work we report the synthesis, characterization by elemental analysis, FTIR, 1H NMR and 13C NMR spectra of the heteroleptic complexes [Ag3SDM(SCN)2]·H2O and [Ag2(SDM)2o-phenanthroline]·H2O, named as AgSDM-SCN and AgSDM-phen, respectively, and the biological properties (lipophilicity, antifungal, phyto, cyto and genotoxicity) of AgSDM-SCN, AgSDM-phen and the homoleptic one: AgSDM. 1H NMR spectra show that the sulfonamide moiety loses its acidic proton in both complexes, in agreement with the FTIR results. The three complexes showed a moderate antifungal activity, mainly against the yeasts Candida albicans, C. tropicalis and Cryptococcus neoformans. None of the tested fungi was inhibited by the free ligand. Lipophilicity: log Koctanol/water values were 0.80, 0.84, 0.85, 0.94 and 0.43 for HSDM, NaSDM, AgSDM, AgSDM-SCN and AgSDM-phen respectively, similarly to another sulfa-metal complexes. No genotoxicity or cytotoxicity were observed for AgSDM and AgSDM-SCN in the Allium cepa test, different from AgSDM-phen. Given these results, the studied complexes could be good candidates for further pharmaceutical studies.Fil: Mosconi, Natalia Ester. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Monti, Laura Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Giulidori, Cecilia María del Luján. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Williams, Patricia Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Raimondi, Marcela Patricia. Universidad Nacional de Rosario. Facultad de Ciencias Médicas; ArgentinaFil: Bellú, Sebastián Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Rizzotto, Marcela Adriana. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentin

Nitrogen abundances in damped Lyman α systems: the combined effects of SNII and SNIa in a hierarchical clustering scenario

The combined enrichment of supernovae (SN) types II and I in a hierarchical clustering scenario could produce regions with low N content with respect to α elements, consistent with observed values measured in damped Lyman α systems (DLAs). We have studied the formation of DLAs in a hierarchical clustering scenario under the hypothesis that the building blocks of current field galaxies could be part of the structures mapped by DLAs. In our models the effects of the non-linear evolution of the structure (which produces bursty star formation histories, gas infall, etc.) and the contributions of SNIa and SNII are found to be responsible of producing these N regions with respect to the α elements. Although SNIa are not main production sites for Si or O, because of the particular timing between SNIa and SNII, their contributions can help to produce clouds with such abundances. Consistently, we found the simulated low nitrogen DLAs to have subsolar [Fe/H]. We show that low nitrogen DLAs have experienced important star formation activity in the past with higher efficiency than normal DLAs. Our chemical model suggests that SNIa play a relevant role in the determination of the abundance pattern of DLA and, that the observed low nitrogen DLA frequency could be explained taking into account the time-delay of ≈0.5 Gyr introduced by these supernova to release metals.Facultad de Ciencias Astronómicas y Geofísica

Building blocks in hierarchical clustering scenarios and their connection with damped Lyα systems

We carried out a comprehensive analysis of the chemical properties of the interstellar medium (ISM) and the stellar population (SP) of current normal galaxies and their progenitors in a hierarchical clustering scenario. We compared the results with observations of damped Lyman- α systems (DLAs) under the hypothesis that, at least, part of the observed DLAs could originate in the building blocks of present-day normal galaxies. We used a hydrodynamical cosmological code which includes star formation and chemical enrichment. Galaxy-like objects are identified at z = 0 and then followed back in time. Random lines of sight (LOS) are drawn through these structures in order to mimic damped Lyman-α systems. We then analysed the chemical properties of the ISM and SP along the LOS. We found that the progenitors of current galaxies in the field with mean L -1 could be the associated DLA galaxies. For these systems we detected a trend for (L/L*) to increase with redshift. We found moderate metallicity evolution for [Zn/H], [Fe/H] and [Si/H]. However, when we applied the observational filter suggested by Boissé et al. (1998) in order to restrict the sample to the observed limits in densities and metallicities, we found mild evolution consistent with observational results that include dust corrections. [Si/Fe] and [S/Fe] show weak α-enhancement in agreement with observations corrected by dust depletion. We found α/Fe in the ISM and SP to have more homogeneous abundances than [Fe/H] and [Zn/H]. In our models, the global metallicity evolution is driven by the high metallicity and high column density simulated DLAs, which have low impact parameters (b 8 M⊙. Our results suggest that geometrical effects could be the mechanism responsible for the non-detectability of high-metallicity and high-column-density DLAs. We found sub-DLAs to map preferentially the outskirts of the simulated DLA galaxies. Hence, they can contribute to the study of the metallicity of the galactic structure as a function of redshift. An analysis of the metallicity content of the ISMs and SPs of the galaxy-like objects as a function of redshift shows the formation of a central stellar mass concentration with nearly solar metallicity at all redshifts while stars in the outer parts of these objects have lower metallicities. The gas content becomes enriched progressively with redshift and at all radii. The abundance properties of the galaxy-like objects and the simulated DLAs are the results of the contribution of type la and II Supernovae and gas infall from the dark matter haloes with a timing settled by their particular evolution history in a hierarchical clustering scenario. Our results suggest that the mild evolution detected in the observations could arise from a conspiracy of all of these processes.Facultad de Ciencias Astronómicas y Geofísica

Exploración de la habitabilidad en viviendas sociales construidas por el estado en la ciudad de Rosario

El trabajo explora la habitabilidad higrotérmica y ventilativa de dos conjuntos de viviendas de interés social construidas por el Estado provincial (Dirección Provincial de Vivienda y Urbanismo) y municipal (Servicio Público de la Vivienda). Se realiza una evaluación térmica estival e invernal para ambas viviendas, se analiza la ventilación de confort como estrategia pasiva para reducir las cargas térmicas y se verifica el riesgo de condensación superficial. Se presentan estrategias de ajuste para mejorar las condiciones de confort dado que la habitabilidad implementada en el diseño y construcción es mínima. Se analizan los reales consumos de energía eléctrica anual verificándose la precariedad constructiva de los planteos juntamente con un desconocimiento de la valoración real de la energía por parte de los ocupantes.The research work explores higrothermal and ventilative habitabillity of two low-income dwellings neighbourhoods built by Provincial State(Provincial Board of Housing and Planning) and Municipal one (Housing Public Service). Summer and winter evaluation as well as ventilation analysis, as a passive strategy to reduce thermal loads, are performed for both cases. Surface condensation risk is verified. Adjustment strategies are presented to improve comfort conditions, due to the minimum habitability implemented in design and construction. Real annual energy consumption shows inadequate building performance and the lack of real energy value from occupants.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Incorporación de aspectos higrotérmicos y demanda energética de las construcciones en reglamento de edificación de Rosario : Verificación de su aplicación en un edificio en altura del área central

Las tipologías edilicias en el área central de Rosario evidencian un total desinterés en términos de habitabilidad cuantitativa y cualitativa. Se presenta la Ordenanza Nº 8757, que incorpora al Reglamento de Edificación de la Ciudad de Rosario la Sección “Aspectos Higrotérmicos y Demanda Energética de las Construcciones”, avanzando en el establecimiento de normas legales que apunten a regular las características constructivas con incidencia en los consumos energéticos para climatización y garantizar estándares mínimos de confort de los edificios. Se aplica a un edificio de oficinas, compacto y hermético, ubicado en el área central de Rosario. Se evalúan los parámetros higrotérmicos de diseño, los valores de transmitancia térmica de los componentes de la envolvente, la verificación del riesgo de condensación superficial e intersticial en los cerramientos, y la demanda energética de calefacción y refrigeración y se analizan los resultados con el objeto de mejorar la eficiencia energética del ambiente construido.Architectonic typologies located in the central area of Rosario city disregard quantitative and qualitative habitability. Ordinance Nº 8567 is presented and will be enclosed in Rosario Building Regulations under the section “Higrothermal Aspects and Energy Demand in Buildings”. This one tends to establish legal regulations about buildings features with incidence on energy consumption for interior conditioning and to guarantee minimum comfort standards. A compact and high office building, located in the central area of Rosario has been selected to apply the ordinance. Hygrothermal design parameters, envelope thermal transmittance, energy demands for heating, cooling and condensation prevention on building assembly are evaluated. Results are analyzed so as to improve energy efficiency of the built environment.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Dark matter response to galaxy formation

We have resimulated the six galaxy-sized haloes of the Aquarius Project including metal-dependent cooling, star formation and supernova feedback. This allows us to study not only how dark matter haloes respond to galaxy formation, but also how this response is affected by details of halo assembly history. In agreement with previous work, we find baryon condensation to lead to increased dark matter concentration. Dark matter density profiles differ substantially in shape from halo to halo when baryons are included, but in all cases the velocity dispersion decreases monotonically with radius. Some haloes show an approximately constant dark matter velocity anisotropy with $\beta \approx 0.1-02$, while others retain the anisotropy structure of their baryon-free versions. Most of our haloes become approximately oblate in their inner regions, although a few retain the shape of their dissipationless counterparts. Pseudo-phase-space densities are described by a power law in radius of altered slope when baryons are included. The shape and concentration of the dark matter density profiles are not well reproduced by published adiabatic contraction models. The significant spread we find in the density and kinematic structure of our haloes appears related to differences in their formation histories. Such differences already affect the final structure in baryon-free simulations, but they are reinforced by the inclusion of baryons, and new features are produced. The details of galaxy formation need to be better understood before the inner dark matter structure of galaxies can be used to constrain cosmological models or the nature of dark matter.Comment: 14 pages, 9 figures. Accepted MNRAS. Revised version includes discussion on resolution effects and minor changes