Browsing by Author "Hale, Catherine Laura"

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    MIGHTEE: the continuum survey data release 1
    (Oxford University Press, 2025) Jarvis, Matthew J.; An, Fangxia; Hale, Catherine Laura
    The MeerKAT International GHz Tiered Extragalactic Exploration Surv e y (MIGHTEE) is one of the large surv e y projects using the MeerKAT telescope, co v ering four fields that have a wealth of ancillary data available. We present Data Release 1 of the MIGHTEE continuum surv e y, releasing total intensity images and catalogues o v er ∼20 de g 2 , across three fields at ∼1.2-1.3 GHz. This includes 4.2 de g 2 o v er the Cosmic Evolution Surv e y (COSMOS) field, 14.4 de g 2 o v er the XMM Large-Scale Structure (XMM-LSS) field and deeper imaging o v er 1.5 de g 2 of the Extended Chandra Deep Field South (CDFS). We release images at both a lower resolution (7-9 arcsec) and higher resolution ( ∼5 arcsec). These images have central rms sensitivities of ∼1 . 3 -2.7 μJy beam -1 ( ∼1 . 2 -3.6 μJy beam -1 ) in the lower (higher) resolution images, respectively. We also release catalogues comprised of ∼144 000 ( ∼114 000) sources using the lower (higher) resolution images. We compare the astrometry and flux-density calibration with the Early Science data in the COSMOS and XMM-LSS fields and previous radio observations in the CDFS field, finding broad agreement. Furthermore, we extend the source counts at the ∼10 μJy level to these larger areas ( ∼20 deg 2 ) and, using the areal co v erage of MIGHTEE we measure the sample variance for differing areas of sky. We find a typical sample variance of 10 -20 per cent for 0.3 and 0.5 de g 2 subre gions at S 1 . 4 ≤200 μJy, which increases at brighter flux densities, given the lower source density and expected higher galaxy bias for these sources.
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    The clustering of active galactic nuclei and star-forming galaxies in the LoTSS Deep Fields
    (Oxford University Press, 2025) Jarvis, Matthew; Hale, Catherine Laura; Best, Phillip
    Using deep observations across three of the LOFAR Two-metre Sky Survey Deep Fields, this work measures the angular clustering of star-forming galaxies (SFGs) and low-excitation radio galaxies (LERGs) to 1.5 for faint sources, 200 Jy. We measure the angular auto-correlation of LOFAR sources in redshift bins and their cross-correlation with multiwavelength sources to measure the evolving galaxy bias for SFGs and LERGs. Our work shows the bias of the radio-selected SFGs increases from = at 0.2 to = at 1.2; faster than the assumed models adopted in previous LOFAR cosmology studies (at sensitivities where active galactic nuclei dominate), but in broad agreement with previous work. We further study the luminosity dependence of bias for SFGs and find little evidence for any luminosity dependence at fixed redshift, although uncertainties remain large for the sample sizes available. The LERG population instead shows a weaker redshift evolution with = at 0.7 to = at 1.2, though it is also consistent with the assumed bias evolution model () within the measured uncertainties. For those LERGs that reside in quiescent galaxies, there is weak evidence that they are more biased than the general LERG population and evolve from = at 0.7 to = at 1.2. This suggests the halo environment of radio sources may be related to their properties. These measurements can help constrain models for the bias evolution of these source populations, and can help inform multi-tracer analyses.