Faint Galaxy Number Counts in the Durhamand SDSS Catalogues

Abstract

Galaxy number counts in the $K$-, $H$-, $I$-, $R$-, $B$- and $U$-bands from the Durham Extragalactic Astronomy and Cosmology catalogue could be well-fitted over their whole range using luminosity function (LF) parameters derived from the SDSS at the bright region and required only modest luminosity evolution with the steepening of the LF slope ($\alpha$), except for a sudden steep increase in the $B$-band and a less steep increase in the $U$-band at faint magnitudes that required a starburst evolutionary model to account for the excess faint number counts. A cosmological model treating Hubble expansion as an Einstein curvature required less correction at faint magnitudes than a standard $\Lambda$CDM model, without requiring dark matter or dark energy. Data from DR17 of the SDSS in the $g$, $i$, $r$, $u$ and $z$ bands over two areas of the sky centred on the North Galactic Cap (NGC) and above the South Galactic Cap (SGC), with areas of 5954 and 859 sq. deg., respectively, and a combined count of 622,121 galaxies, were used to construct bright galaxy number counts and galaxy redshift/density plots within the limits of redshift $\le 0.4$ and mag $\le 20$. Their comparative densities confirmed an extensive void in the Southern sky with a deficit of 26\% out to a redshift $z$$\le$0.15. Although not included in the number count data set because of its incompleteness at fainter magnitudes, extending the SDSS redshift-number count survey to fainter and more distant galaxies with redshift $\le 1.20$ showed a secondary peak in the number counts with many QSOs, bright X-ray and radio sources, and evolving irregular galaxies with rapid star formation rates. This sub-population at redshifts of 0.45--0.65 may account for the excess counts observed in the $B$-band.

20 pages, 15 figures

References in corpus (8)

• A population of red candidate massive galaxies ~600 Myr after the Big Bang
• CEERS Key Paper I: An Early Look into the First 500 Myr of Galaxy Formation with JWST
• The Evolution of Galaxy Number Density at z < 8 and its Implications
• Deep U band and R imaging of GOODS-South: Observations,data reduction and first results
• Radio Loud and Radio Quiet Quasars
• The radio emission from Active Galactic Nuclei
• Starburst and post-starburst high-redshift protogalaxies: The feedback impact of high energy cosmic rays
• An Estimator for the lensing potential from galaxy number counts