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G. Giardino

Publications and source records attributed to G. Giardino.

75 records · Page 5Linked to original sources

The angular power spectrum of radio emission at 2.3 GHz

We have analysed the Rhodes/HartRAO survey at 2326 MHz and derived the global angular power spectrum of Galactic continuum emission. In order to measure the angular power spectrum of the diffuse component, point sources were removed from the map by median filtering. A least-square fit to the angular power spectrum of the entire survey with a power law spectrum C_l proportional to l^{-alpha}, gives alpha = 2.43 +/- 0.01 for l = 2-100. The angular power spectrum of radio emission appears to steepen at high Galactic latitudes and for observed regions with |b| > 20 deg, the fitted spectral index is alpha = 2.92 +/- 0.07. We have extrapolated this result to 30 GHz (the lowest frequency channel of Planck) and estimate that no significant contribution to the sky temperature fluctuation is likely to come from synchrotron at degree-angular scales

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Analysis of CMB foregrounds using a database for Planck

Within the scope of the Planck IDIS (Integrated Data Information System) project we have started to develop the data model for time-ordered data and full-sky maps. The data model is part of the Data Management Component (DMC), a software system designed according to a three-tier architecture which allows complete separation between data storage and processing. The DMC is already being used for simulation activities and the modeling of some foreground components. We have ingested several Galactic surveys into the database and used the science data-access interface to process the data. The data structure for full-sky maps utilises the HEALPix tessellation of the sphere. We have been able to obtain consistent measures of the angular power spectrum of the Galactic radio continuum emission between 408 MHz and 2417 MHz.

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Constraints on the physical properties of the damped Ly-alpha system of Q0000-2619 at z = 3.054

We present the detection of CII and CII* absorption in the z = 3.0543 damped Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine structure excitation temperature between 19.6 and 21.6 K. The upper value sets a strict upper limit on the CMB temperature at this redshift, which is consistent with the predicted value of 11.05 K from standard cosmology. Under the assumptions of an ionization degree ranging from 0 to 10%, a gas kinetic temperature between 100 and 10000 K and a UV field with a Milky Way spectrum, the density of the absorber is constrained to be between 0.7 and 40 cm^-3 and the H-ionizing flux between 1 and 80 times the intensity of the Galactic UV field. If the damped Ly-alpha system is assumed to be homogeneous, the implication is that its size in the direction of the line of sight must be between 1 and 100 pc.

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