A multifrequency study of the Lockman Hole region: preparing for a LOFAR deep survey

Guglielmino, Gabriele (2013) A multifrequency study of the Lockman Hole region: preparing for a LOFAR deep survey, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Astronomia, 25 Ciclo. DOI 10.6092/unibo/amsdottorato/5175.
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Abstract

In this thesis, we have presented two deep 1.4 GHz and 345 MHz overlapping surveys of the Lockman Hole field taken with the Westerbork Synthesis Radio Telescope. We extracted a catalogue of ~6000 radio sources from the 1.4 GHz mosaic down to a flux limit of ~55 μJy and a catalogue of 334 radio sources down to a flux limit of ~4 mJy from the inner 7 sq. degree region of the 345 MHz image. The extracted catalogues were used to derive the source number counts at 1.4 GHz and at 345 MHz. The source counts were found to be fully consistent with previous determinations. In particular the 1.4 GHz source counts derived by the present sample provide one of the most statistically robust determinations in the flux range 0.1 < S < 1 mJy. During the commissioning program of the LOFAR telescope, the Lockman Hole field was observed at 58 MHz and 150 MHz. The 150 MHz LOFAR observation is particularly relevant as it allowed us to obtain the first LOFAR flux calibrated high resolution image of a deep field. From this image we extracted a preliminary source catalogue down to a flux limit of ~15 mJy (~10σ), that can be considered complete down to 20‒30 mJy. A spectral index study of the mJy sources in the Lockman Hole region, was performed using the available catalogues ( 1.4 GHz, 345 MHz and 150 MHz) and a deep 610 MHz source catalogue available from the literature (Garn et al. 2008, 2010).

Abstract
Tipologia del documento
Tesi di dottorato
Autore
Guglielmino, Gabriele
Supervisore
Co-supervisore
Dottorato di ricerca
Scuola di dottorato
Scienze matematiche, fisiche ed astronomiche
Ciclo
25
Coordinatore
Settore disciplinare
Settore concorsuale
URN:NBN
DOI
10.6092/unibo/amsdottorato/5175
Data di discussione
26 Febbraio 2013
URI

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