Apertif 1.4 GHz continuum observations of the Boötes field and their combined view with LOFAR

• DOI: 10.48550/arxiv.2306.03710
• Publication Date: 2023-01-01
• Authors: A. M. Kutkin; Tom Oosterloo; R. Morganti; A. R. Offringa; Elizabeth A. K. A...; B. Adebahr; Helga Dénes; Kelley M. Hess; J. M. van der Hulst; W. J. G. de Blok; Ayhan Bozkurt; W. A. van Cappellen; A. W. Gunst; H. A. Holties; J. van Leeuwen; G. M. Loose; L. C. Oostrum; D. Vohl; Stefan J. Wijnholds; J. Ziemke
• Keywords: LOFAR

We present a new image of 26.5 square degree region in the Boötes constellation obtained at 1.4 GHz using Aperture Tile Focus (Apertif) system on Westerbork Synthesis Radio Telescope. use newly developed processing pipeline which includes direction-dependent self-calibration provides significant improvement quality images compared to those released as part Apertif first data release. For region, we mosaic 187 and extract source catalog. The has an angular resolution 27${\times}$11.5 arcseconds median background noise 40 $μ$Jy/beam. catalog 8994 sources is complete down 0.3 mJy level. combine with LOFAR field 54 150 MHz study spectral properties sources. find flattening towards low flux density Using index limits from non-detections derive that up 9 percent have ultra-steep spectra slope steeper than -1.2. Steepening increasing redshift also seen showing different dependency for low-frequency high frequency one. This can be explained by population having concave radio turnover around band. Additionally, discuss cases individual extended interesting resolved structure. With improved pipeline, aim continue wide-area surveys release several famous fields.