One- and Two-point Source Statistics from the LOFAR Two-metre Sky Survey First Data Release. (arXiv:1908.10309v2 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Siewert_T/0/1/0/all/0/1">Thilo M. Siewert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hale_C/0/1/0/all/0/1">Catherine Hale</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bhardwaj_N/0/1/0/all/0/1">Nitesh Bhardwaj</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Biermann_M/0/1/0/all/0/1">Marian Biermann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bacon_D/0/1/0/all/0/1">David J. Bacon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jarvis_M/0/1/0/all/0/1">Matt Jarvis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rottgering_H/0/1/0/all/0/1">Huub R&#xf6;ttgering</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schwarz_D/0/1/0/all/0/1">Dominik J. Schwarz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shimwell_T/0/1/0/all/0/1">Timothy Shimwell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Best_P/0/1/0/all/0/1">Philip N. Best</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Duncan_K/0/1/0/all/0/1">Kenneth J. Duncan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hardcastle_M/0/1/0/all/0/1">Martin J. Hardcastle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sabater_J/0/1/0/all/0/1">Jose Sabater</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tasse_C/0/1/0/all/0/1">Cyril Tasse</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+White_G/0/1/0/all/0/1">Glenn J. White</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Williams_W/0/1/0/all/0/1">Wendy L. Williams</a>

The LOFAR Two-metre Sky Survey (LoTSS) will map the complete Northern sky and
provide an excellent opportunity to study the distribution and evolution of the
large-scale structure of the Universe. We study the completeness of the LoTSS
first data release (DR1) and find a point-source completeness of 99 % above
flux densities of 0.8 mJy and define a suite of quality cuts. We determine the
count-in-cell statistics and differential source counts statistic and measure
the angular two-point correlation function of the LoTSS radio sources. The
counts-in-cell statistic reveals that the distribution of radio sources cannot
be described by a spatial Poisson process. Instead, a good fit is provided by a
compound Poisson distribution. The differential source counts are in good
agreement with previous findings in deep fields at low radio frequencies.
Simulated catalogues from the SKA design study sky and the Tiered Radio
Extragalactic Continuum Simulation match with our findings. The angular
two-point correlation is $<10^{-2}$ at angular scales $> 1$ deg. Restricting
the value added source catalogue to low-noise regions and a flux density
threshold of 2 mJy provides our most reliable estimate of the angular two-point
correlation. For smaller flux density thresholds systematic issues are
identified, most likely related to the flux density calibration of the
individual pointings. Based on the distribution of photometric redshifts of
LoTSS sources and the Planck 2018 best-fit cosmological model, the
theoretically predicted angular two-point correlation between 0.1 deg and 6 deg
agrees with the measured clustering for a subsample of radio sources with
redshift information. We find agreement with the expectation of large-scale
statistical isotropy of the radio sky at the per cent level. The angular
two-point correlation agrees well with the expectation of the cosmological
standard model. (abbreviated)

The LOFAR Two-metre Sky Survey (LoTSS) will map the complete Northern sky and
provide an excellent opportunity to study the distribution and evolution of the
large-scale structure of the Universe. We study the completeness of the LoTSS
first data release (DR1) and find a point-source completeness of 99 % above
flux densities of 0.8 mJy and define a suite of quality cuts. We determine the
count-in-cell statistics and differential source counts statistic and measure
the angular two-point correlation function of the LoTSS radio sources. The
counts-in-cell statistic reveals that the distribution of radio sources cannot
be described by a spatial Poisson process. Instead, a good fit is provided by a
compound Poisson distribution. The differential source counts are in good
agreement with previous findings in deep fields at low radio frequencies.
Simulated catalogues from the SKA design study sky and the Tiered Radio
Extragalactic Continuum Simulation match with our findings. The angular
two-point correlation is $<10^{-2}$ at angular scales $> 1$ deg. Restricting
the value added source catalogue to low-noise regions and a flux density
threshold of 2 mJy provides our most reliable estimate of the angular two-point
correlation. For smaller flux density thresholds systematic issues are
identified, most likely related to the flux density calibration of the
individual pointings. Based on the distribution of photometric redshifts of
LoTSS sources and the Planck 2018 best-fit cosmological model, the
theoretically predicted angular two-point correlation between 0.1 deg and 6 deg
agrees with the measured clustering for a subsample of radio sources with
redshift information. We find agreement with the expectation of large-scale
statistical isotropy of the radio sky at the per cent level. The angular
two-point correlation agrees well with the expectation of the cosmological
standard model. (abbreviated)

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