The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for [CII] Line and Dust Emission in 6 < z < 8 galaxies

We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212–272 GHz, encompass approximately the range of 6 4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S_(1.2 mm) = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) M⊙ yr^(-1). We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L_([C II]) versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe

Diagnóstico sobre la incorporación de la Nch 2957/2006 en los viveros forestales de la Región del Maule

Aravena, F. Ingeniera Forestal. Universidad de Talca, Talca. Chile. Ponce, M. Facultad de Ciencias Forestales. Universidad de Talca. Casilla 747, Talca. Chile.La investigación estuvo enfocada a diagnosticar la incorporación de la NCh2957/2006 en los viveros forestales de la Región del Maule. Para ello se empleó la “Taxonomía de Wroclaw”, obteniéndose tres clases de acercamiento a la norma. Se descubrió que lo anterior estaría en función de las capacidades y objetivos de la producción. Los viveros con un nivel de gestión alto, orientados al autoabastecimiento o a cumplir contratos con terceros, estarían más cerca del cumplimiento. Se dio también una relación directa entre: nivel de acercamiento, precios, y niveles de venta. Al evaluar las variables normadas, el nivel alto (clase I) obtuvo el 65% de las calificaciones de “buena a excelente”; el nivel medio (clase II), alcanzó el 54% de esta calificación; y en el nivel bajo (clase III), sólo el 33% de las variables resultaron como “buena”. La clase I presenta alta capacidad empresarial, con orientación al autoabastecimiento de planes de forestación/reforestación o a cumplir contratos, además demuestran interés en la norma. La clase II tiene nivel empresarial medio a alto, destinando la producción a sus patrimonios, o a cumplir contratos, y expresan escaso interés. La clase III, debido a sus deficientes capacidades, errónea noción de calidad y nulo interés en el tema, no podría certificarse por este sistema de evaluación. Se considera necesaria la implementación de la norma, pues el mercado de plantas forestales carece de estándares de calidad y se estarían empleando conceptos erróneos, sumado al desconocimiento de las ventajas que entrega la implementación de un sistema de calidad

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies

We present an analysis of a deep (1σ = 13 μJy) cosmological 1.2 mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin^2 covered by ASPECS we detect nine sources at >3.5σ significance at 1.2 mm. Our ALMA-selected sample has a median redshift of z = 1.6 ± 0.4, with only one galaxy detected at z > 2 within the survey area. This value is significantly lower than that found in millimeter samples selected at a higher flux density cutoff and similar frequencies. Most galaxies have specific star formation rates (SFRs) similar to that of main-sequence galaxies at the same epoch, and we find median values of stellar mass and SFRs of 4.0 x 10^(10)M⊙ and ~40 M⊙ yr^(-1), respectively. Using the dust emission as a tracer for the interstellar medium (ISM) mass, we derive depletion times that are typically longer than 300 Myr, and we find molecular gas fractions ranging from ~0.1 to 1.0. As noted by previous studies, these values are lower than those using CO-based ISM estimates by a factor of ~2. The 1 mm number counts (corrected for fidelity and completeness) are in agreement with previous studies that were typically restricted to brighter sources. With our individual detections only, we recover 55% ± 4% of the extragalactic background light (EBL) at 1.2 mm measured by the Planck satellite, and we recover 80% ± 7% of this EBL if we include the bright end of the number counts and additional detections from stacking. The stacked contribution is dominated by galaxies at z ~ 1-2, with stellar masses of (1–3) × 10^(10) M⊙. For the first time, we are able to characterize the population of galaxies that dominate the EBL at 1.2 mm

Large gas reservoirs and free–free emission in two lensed star-forming galaxies at z = 2.7

We report the detection of CO(1–0) line emission in the bright, lensed star-forming galaxies SPT-S 233227−5358.5 (z = 2.73) and SPT-S 053816−5030.8 (z = 2.78), using the Australia Telescope Compact Array. Both galaxies were discovered in a large-area millimetre survey with the South Pole Telescope (SPT) and found to be gravitationally lensed by intervening structures. The measured CO intensities imply galaxies with molecular gas masses of (3.2 ± 0.5) × 10^10(μ/15)^(−1)(X_CO/0.8) and (1.7 ± 0.3) × 10^10(μ/20)^(−1)(XCO/0.8) M_⊙, and gas depletion time-scales of 4.9 × 107(X_CO/0.8) and 2.6 × 10^7(X_CO/0.8) yr, respectively, where μ corresponds to the lens magnification and X_CO is the CO luminosity to gas mass conversion factor. In the case of SPT-S 053816−5030.8, we also obtained significant detections of the rest-frame 115.7 and 132.4 GHz radio continuum. Based on the radio-to-infrared spectral energy distribution and an assumed synchrotron spectral index, we find that 42 ± 10 and 55 ± 13 per cent of the flux at rest-frame 115.7 and 132.4 GHz arises from free–free emission. We find a radio-derived intrinsic star formation rate of 470 ± 170 M_⊙ yr^(−1), consistent within the uncertainties with the infrared estimate. Based on the morphology of this object in the source plane, the derived gas mass and the possible flattening of the radio spectral index towards low frequencies, we argue that SPT-S 053816−5030.8 exhibits properties compatible with a scaled-up local ultraluminous infrared galaxy

COLDz: Karl G. Jansky Very Large Array discovery of a gas-rich galaxy in COSMOS

The broad spectral bandwidth at mm and cm-wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48, through the detection of CO(1-0) line emission in the COLDz survey, through a sensitive, Ka-band (31 to 39 GHz) VLA survey of a 6.5 square arcminute region of the COSMOS field. We argue that the broad line (FWHM ~570 +/- 80 km/s) is most likely to be CO(1-0) at z=2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z = 3.2 +/- 0.4. The CO(1-0) line luminosity is L'_CO = (2.2 +/- 0.3) x 10^{10} K km/s pc^2, suggesting a cold molecular gas mass of M_gas ~ (2 - 8)x10^{10}M_solar depending on the assumed value of the molecular gas mass to CO luminosity ratio alpha_CO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L_IR = 2.5x10^{12} L_solar and the star-formation rate is ~250 M_solar/yr, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114+/-19 L_solar/(K km/s pc^2), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future

CO(1-0) line imaging of massive star-forming disc galaxies at z=1.5-2.2

We present detections of the CO(J= 1-0) emission line in a sample of four massive star-forming galaxies at z~1.5-2.2 obtained with the Karl G. Jansky Very Large Array (VLA). Combining these observations with previous CO(2-1) and CO(3-2) detections of these galaxies, we study the excitation properties of the molecular gas in our sample sources. We find an average line brightness temperature ratios of R_{21}=0.70+\-0.16 and R_{31}=0.50+\-0.29, based on measurements for three and two galaxies, respectively. These results provide additional support to previous indications of sub-thermal gas excitation for the CO(3-2) line with a typically assumed line ratio R_{31}~0.5. For one of our targets, BzK-21000, we present spatially resolved CO line maps. At the resolution of 0.18'' (1.5 kpc), most of the emission is resolved out except for some clumpy structure. From this, we attempt to identify molecular gas clumps in the data cube, finding 4 possible candidates. We estimate that <40 % of the molecular gas is confined to giant clumps (~1.5 kpc in size), and thus most of the gas could be distributed in small fainter clouds or in fairly diffuse extended regions of lower brightness temperatures than our sensitivity limit