Astrophysics - Cosmology and Nongalactic Astrophysics
Astrophysics - Astrophysics of Galaxies
Beschreibung:
Covering ∼5600 deg2 to rms sensitivities of ∼70−100 μJy beam−1, the LOFAR Two-metre Sky Survey Data Release 2 (LoTSS-DR2) provides the largest low-frequency (∼150 MHz) radio catalogue to date, making it an excellent tool for large-area radio cosmology studies. In this work, we use LoTSS-DR2 sources to investigate the angular two-point correlation function of galaxies within the survey. We discuss systematics in the data and an improved methodology for generating random catalogues, compared to that used for LoTSS-DR1, before presenting the angular clustering for ∼900,000 sources ≥1.5 mJy and a peak signal-to-noise ≥7.5 across ∼80% of the observed area. Using the clustering we infer the bias assuming two evolutionary models. When fitting {angular scales of 0.5≤θ<5°, using a linear bias model, we find LoTSS-DR2 sources are biased tracers of the underlying matter, with a bias of bC=2.14+0.22−0.20 (assuming constant bias) and bE(z=0)=1.79+0.15−0.14 (for an evolving model, inversely proportional to the growth factor), corresponding to bE=2.81+0.24−0.22 at the median redshift of our sample, assuming the LoTSS Deep Fields redshift distribution is representative of our data. This reduces to bC=2.02+0.17−0.16 and bE(z=0)=1.67+0.12−0.12 when allowing preferential redshift distributions from the Deep Fields to model our data. Whilst the clustering amplitude is slightly lower than LoTSS-DR1 (≥2 mJy), our study benefits from larger samples and improved redshift estimates. (assuming constant bias) and bE(z=0)=1.79+0.15−0.14 (for an evolving model, inversely proportional to the growth factor), corresponding to bE= 2.81+0.24-0.12 at the median redshift of our sample, assuming the LoTSS Deep Fields redshift distribution is representative of our data. This reduces to bC=2.02+0.17−0.16 and bE(z=0)=1.67+0.12−0.12when allowing preferential redshift distributions from the Deep Fields to model our data. Whilst the clustering amplitude is slightly lower than LoTSS-DR1 (≥2 mJy), our study benefits from larger samples and improved redshift estimates.