Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude

We estimate the 21 cm Radio Background from accretion onto the first intermediate-mass Black Holes between $z\approx 30$ and $z\approx 16$. Combining potentially optimistic, but plausible, scenarios for black hole formation and growth with empirical correlations between luminosity and radio-emission observed in low-redshift active galactic nuclei, we find that a model of black holes forming in molecular cooling halos is able to produce a 21 cm background that exceeds the Cosmic Microwave Background (CMB) at $z \approx 17$ though models involving larger halo masses are not entirely excluded. Such a background could explain the surprisingly large amplitude of the 21 cm absorption feature recently reported by the EDGES collaboration. Such black holes would also produce significant X-ray emission and contribute to the $0.5-2$ keV soft X-ray background at the level of $\approx 10^{-13}-10^{-12}$ erg sec$^{-1}$ cm$^{-2}$ deg$^{-2}$, consistent with existing constraints. In order to avoid heating the IGM over the EDGES trough, these black holes would need to be obscured by Hydrogen column depths of $N_\text{H} \sim 5 \times 10^{23} \text{cm}^{-2}$. Such black holes would avoid violating contraints on the CMB optical depth from Planck if their UV photon escape fractions were below $f_{\text{esc}} \lesssim 0.1$, which would be a natural result of $N_\text{H} \sim 5 \times 10^{23} \text{cm}^{-2}$ imposed by an unheated IGM.Comment: 10 pages, 7 figures, accepted to ApJ, replacement to match submitted versio

Equivalence of categories of simple Lie algebras in positive characteristic

In this paper we first study some properties of the finite-dimensional simple restricted Lie algebras. In the literature is found a one-to-one correspondence between them and finite-dimensional simple Lie algebras over a field of positive characteristic. Motivated by this fact, we give a one-to-one correspondence between their morphisms, which allow us to conclude that such categories are equivalen

Nematic Films and Radially Anisotropic Delaunay Surfaces

We develop a theory of axisymmetric surfaces minimizing a combination of surface tension and nematic elastic energies which may be suitable for describing simple film and bubble shapes. As a function of the elastic constant and the applied tension on the bubbles, we find the analogues of the unduloid, sphere, and nodoid in addition to other new surfaces.Comment: 15 pages, 18 figure

Tectonic setting of the northernmost volcanic belt of the central cordillera, colombia

The northernmost Colombian recent volcanism is located in the central part of the Central Cordillera between the Romerales and Machín volcanoes. This volcanic belt is bounded by transversal fault systems, observed in an area of 10.000 km2. Radar and Landsat images interpretations, earthquakes locations, relative displacements of blocks, active faults studies and published geological maps were used to constrain this volcanism. Three major fracture orientations systems were recognized in the region. The fist system strikes N-S and is parallel to the Central Cordillera foothills. The second is oriented NW-SE and is related to the Rio Arma Fault and similar structures. The third with a SW-NE tendency is comparable with structures such as the Garrapatas and Ibagué faults. Faulting and recent volcanism relationship was identified, as well as their seismic activity. Additionally, the relative importance of the identified tectonic structures was established. Finally a micro-block is proposed for the region and their relative directions and magnitudes of displacement were determined using GPS methods. This analysis allow us to propose the Ibagué and Arma fault systems as tectonic boundaries of a crustal block that represents the subduction of a slab segment under the continental arch, generating the recent volcanism in this part of the Central Cordillera.   Key words: .  El vulcanismo reciente más septentrional de Colombia, comprendido entre los volcanes Romerales al norte y Cerro Machín al sur, está limitado por grandes sistemas de fallas que cruzan transversalmente el país, los cuales se muestran en este trabajo dentro de un área seleccionada de 10.000 km2 que se estudió a partir de imágenes de radar, Landsat y otros datos como localizaciones de sismos, cálculos de desplazamientos relativos de bloques, mapas de fallas activas y planchas geológicas publicadas. Se reconocieron tres direcciones predominantes de fracturamiento en la zona, una N-S paralela a los piedemontes de la Cordillera Central, otra SW-NE relacionada con fallas como Río Arma o La Pintada y la tercera tendencia SW-NE comparable con la dirección de Garrapatas e Ibagué. Además, se identificó la correlación existente entre las fallas y los volcanes recientes, se diferenció la actividad sísmica asociada con el vulcanismo y con las fallas; se determinó el grado de importancia en la zona de cada uno de los grupos de estructuras tectónicas identificadas y finalmente se reconoció el desplazamiento relativo de un microbloque propuesto para la región. De esta forma y de manera preliminar, se asumen algunos sentidos y magnitudes de desplazamientos, que junto con los demás datos permiten proponer un modelo que relaciona las zonas de falla de Ibagué y Arma como límites tectónicos de un segmento de placa que subduce bajo el arco continental y genera el vulcanismo reciente en esta parte de la Cordillera Central. &nbsp

Tectonic setting of the northernmost volcanic belt of the central cordillera, colombia

The northernmost Colombian recent volcanism is located in the central part of the Central Cordillera between the Romerales and Machín volcanoes. This volcanic belt is bounded by transversal fault systems, observed in an area of 10.000 km2. Radar and Landsat images interpretations, earthquakes locations, relative displacements of blocks, active faults studies and published geological maps were used to constrain this volcanism. Three major fracture orientations systems were recognized in the region. The fist system strikes N-S and is parallel to the Central Cordillera foothills. The second is oriented NW-SE and is related to the Rio Arma Fault and similar structures. The third with a SW-NE tendency is comparable with structures such as the Garrapatas and Ibagué faults. Faulting and recent volcanism relationship was identified, as well as their seismic activity. Additionally, the relative importance of the identified tectonic structures was established. Finally a micro-block is proposed for the region and their relative directions and magnitudes of displacement were determined using GPS methods. This analysis allow us to propose the Ibagué and Arma fault systems as tectonic boundaries of a crustal block that represents the subduction of a slab segment under the continental arch, generating the recent volcanism in this part of the Central Cordillera.   Key words: .  El vulcanismo reciente más septentrional de Colombia, comprendido entre los volcanes Romerales al norte y Cerro Machín al sur, está limitado por grandes sistemas de fallas que cruzan transversalmente el país, los cuales se muestran en este trabajo dentro de un área seleccionada de 10.000 km2 que se estudió a partir de imágenes de radar, Landsat y otros datos como localizaciones de sismos, cálculos de desplazamientos relativos de bloques, mapas de fallas activas y planchas geológicas publicadas. Se reconocieron tres direcciones predominantes de fracturamiento en la zona, una N-S paralela a los piedemontes de la Cordillera Central, otra SW-NE relacionada con fallas como Río Arma o La Pintada y la tercera tendencia SW-NE comparable con la dirección de Garrapatas e Ibagué. Además, se identificó la correlación existente entre las fallas y los volcanes recientes, se diferenció la actividad sísmica asociada con el vulcanismo y con las fallas; se determinó el grado de importancia en la zona de cada uno de los grupos de estructuras tectónicas identificadas y finalmente se reconoció el desplazamiento relativo de un microbloque propuesto para la región. De esta forma y de manera preliminar, se asumen algunos sentidos y magnitudes de desplazamientos, que junto con los demás datos permiten proponer un modelo que relaciona las zonas de falla de Ibagué y Arma como límites tectónicos de un segmento de placa que subduce bajo el arco continental y genera el vulcanismo reciente en esta parte de la Cordillera Central. &nbsp

Fungicidas a partir de extractos vegetales: una alternativa en el manejo integrado de hongos fitopatógenos

Esta revisión ofrece una visión general sobre reportes de evaluación de la actividad biológica in vitro de extractos vegetales sobre hongos fitopatógenos. Se presentan los métodos experimentales para la obtención de extractos vegetales y la caracterización de metabolitos, así como los métodos de inhibición del hongo mediante macro y micrométodos. Por último, se presentan las recomendaciones para clasificar la potencialidad de un extracto vegetal sobre un hongo fitopatógeno con el fin de establecer un enfoque prometedor para el descubrimiento de nuevos agentes antifúngicos en el control etológico y manejo integrado de hongos.This review offers an overview of reports evaluating the in vitro biological activity of plant extracts on pathogenic fungi. We present the experimental methods for obtaining plant extracts and the characterization of metabolites, as well as the methods of inhibition of the fungus by means of macro and micro methods. Finally, we present the recommendations to classify the potentiality of a plant extract on a pathogenic fungus, in order to establish a promising approach for the discovery of new antifungal agents for the ethological control and integrated management of phytopathogenic fungi.Gerencia de Comunicación e Imagen Institucional, DNA SICC, INTAFil: Mesa, Ana María. Universidad de Antioquia. Facultad de Ciencias Exactas y Naturales. Instituto de Biología. Grupo de investigación Agrobiotecnología; ColombiaFil: Marin, P.A. Universidad de Antioquia. Facultad de Ciencias Exactas y Naturales. Instituto de Biología. Grupo de investigación BIOMA; ColombiaFil: Ocampo, O. Universidad de Antioquia. Facultad de Ciencias Exactas y Naturales. Instituto de Biología. Grupo de investigación Agrobiotecnología; ColombiaFil: Calle, J. Universidad de Antioquia. Facultad de Ciencias Exactas y Naturales. Instituto de Biología. Grupo de investigación BIOMA; ColombiaFil: Monsalve Fonnegra, Zulma Isabel. Universidad de Antioquia. Facultad de Ciencias Exactas y Naturales. Instituto de Biología. Grupo de investigación Agrobiotecnología; Colombi

Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude

We estimate the 21 cm radio background from accretion onto the first intermediate-mass black holes between z ≈ 30 and z ≈ 16. Combining potentially optimistic, but plausible, scenarios for black hole formation and growth with empirical correlations between luminosity and radio emission observed in low-redshift active galactic nuclei, we find that a model of black holes forming in molecular cooling halos is able to produce a 21 cm background that exceeds the cosmic microwave background (CMB) at z ≈ 17, though models involving larger halo masses are not entirely excluded. Such a background could explain the surprisingly large amplitude of the 21 cm absorption feature recently reported by the EDGES collaboration. Such black holes would also produce significant X-ray emission and contribute to the 0.5–2 keV soft X-ray background at the level of ≈10^(−13)–10^(−12) erg s^(−1)cm^(−2) deg^(−2), consistent with existing constraints. In order to avoid heating the intergalactic medium (IGM) over the EDGES trough, these black holes would need to be obscured by hydrogen column depths of N_H ~ 5 × 10^(23) cm^(−2). Such black holes would avoid violating constraints on the CMB optical depth from Planck if their UV photon escape fractions were below f_(esc) ≾ 0.1, which would be a natural result of N_H ~ 5 × 10^(23) cm^(−2) being imposed by an unheated IGM

The QUIET Instrument

The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales (~ 1 degree). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 uK sqrt(s)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 uK sqrt(s) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01. The two arrays together cover multipoles in the range l= 25-975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument