Number Density Evolution ofK_s‐Band–Selected High‐Redshift Galaxy Populations in theAKARINorth Ecliptic Pole Field

Abstract

We present the number counts of K s -bandYselected high-redshift galaxy populations such as extremely red objects (EROs), B-, z-, and K-bandYselected galaxies ( BzKs) and distant red galaxies ( DRGs) in the AKARI NEP field. These high-redshift galaxy samples are extracted from a multicolor catalog combining optical data from SuprimeCam on the 8.2 m Subaru Telescope with near-infrared data from the Florida Multiobject Imaging Near-IR Grism Observational Spectrometer on the Kitt Peak National Observatory 2.1 m telescope over 540 arcmin 2 in the NEP region field. The final catalog contains 308 EROs (K s < 19:0; 54% are dusty star-forming EROs, and the rest are passive old EROs), 137 star-forming BzKs, and 38 passive old BzKs (K s < 19:0) and 64 DRGs (K s < 18:6). We also produce individual component source counts for both the dusty star-forming and passive populations. We compare the observed number counts of the high redshift passively evolving galaxy population with a backward pure luminosity evolution ( PLE) model allowing different degrees of number density evolution. We find that the PLE model without density evolution fails to explain the observed counts at faint magnitudes, while the model incorporating negative density evolution is consistent with the observed counts of the passively evolving population. We also compare our observed counts of dusty star-forming EROs with a phenomenological evolutionary model postulating that the nearinfrared EROs can be explained by the source densities of the far-infraredYsubmillimeter populations. Our model predicts that the dusty ERO source counts can be explained assuming a 25% contribution of submillimeter starforming galaxies with the majority of brighter K s -bandYdetected dusty EROs having luminous (rather than HR 10 type ultraluminous) submillimeter counterparts. We propose that the fainter K s > 19:5 population is dominated by the submillijansky submillimeter population. We also predict a turnover in dusty ERO counts around 19 < K s < 20.

The clustering and abundance of star-forming and passive galaxies atz∼ 2

“…The s BzK number counts are significantly higher than those of K06, Blanc et al (2008) and Imai et al (2008) (not plotted); while the p BzK number counts are lower. The UDS field is more than six times larger than that of the K20 survey and four times larger than the one used in Imai et al (2008).…”

“…The s BzK number counts are significantly higher than those of K06, Blanc et al (2008) and Imai et al (2008) (not plotted); while the p BzK number counts are lower. The UDS field is more than six times larger than that of the K20 survey and four times larger than the one used in Imai et al (2008). The combined field used in Blanc et al (2008) is of a similar size to the UDS; cosmic variance is the most likely explanation for the difference in number counts in this case.…”

Evolution of infrared luminosity functions of galaxies in the AKARI NEP-deep field

“…For TIR LFs, we have added 0.05 dex of error for uncertainty in the SED fitting following the discussion in Magnelli et al (2009). We did not consider the uncertainty on the cosmic variance here since the AKARI NEP field covers a large volume and has comparable number counts to other general fields (Imai et al, 2007(Imai et al, , 2008. Each redshift bin we use covers ∼ 10 6 Mpc 3 of volume.…”

A Critical Examination of the Standard Cosmological Model: Toward a Modified Framework for Explaining Cosmic Structure Formation and Evolution

“…Research into the correlation between galaxy numbers and redshift is a key focus in astrophysics. This area of study is instrumental in unraveling the intricate dynamics and formation of structures within the universe [50][51][52][53].…”