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We present an analysis of the radio properties of large samples of Lyman Break Galaxies (LBGs) at $z sim 3$, 4, and 5 from the COSMOS field. The median stacking analysis yields a statistical detection of the $z sim 3$ LBGs (U-band drop-outs), with a 1.4 GHz flux density of $0.90 pm 0.21 mu$Jy. The stacked emission is unresolved, with a size $< 1$, or a physical size $< 8$kpc. The total star formation rate implied by this radio luminosity is $31pm 7$ $M_odot$ year$^{-1}$, based on the radio-FIR correlation in low redshift star forming galaxies. The star formation rate derived from a similar analysis of the UV luminosities is 17 $M_odot$ year$^{-1}$, without any correction for UV dust attenuation. The simplest conclusion is that the dust attenuation factor is 1.8 at UV wavelengths. However, this factor is considerably smaller than the standard attenuation factor $sim 5$, normally assumed for LBGs. We discuss potential reasons for this discrepancy, including the possibility that the dust attenuation factor at $z ge 3$ is smaller than at lower redshifts. Conversely, the radio luminosity for a given star formation rate may be systematically lower at very high redshift. Two possible causes for a suppressed radio luminosity are: (i) increased inverse Compton cooling of the relativistic electron population due to scattering off the increasing CMB at high redshift, or (ii) cosmic ray diffusion from systematically smaller galaxies. The radio detections of individual sources are consistent with a radio-loud AGN fraction of 0.3%. One source is identified as a very dusty, extreme starburst galaxy (a submm galaxy).
We analyse the 267 radio sources from our deep (flux limit of 42 microJy at the field center at 1.4 GHz) Chandra Deep Field South 1.4 and 5 GHz VLA survey. The radio population is studied by using a wealth of multi-wavelength information, including m
A deep mid- and far-infrared survey in the Extended Groth Strip (EGS) area gives 3.6 to 8micron flux densities or upper limits for 253 Lyman Break Galaxies (LBGs). The LBGs are a diverse population but with properties correlated with luminosity. The
We separate the extragalactic radio source population above ~50 uJy into active galactic nuclei (AGN) and star-forming sources. The primary method of our approach is to fit the infrared spectral energy distributions (SEDs), constructed using Spitzer/
Dark matter haloes in which galaxies reside are likely to have a significant impact on their evolution. We investigate the link between dark matter haloes and their constituent galaxies by measuring the angular two-point correlation function of radio
We investigate the linear radio size properties of the $mu$Jy populations of radio-selected active galactic nuclei (AGN) and star-forming galaxies (SFGs) using a multi-resolution catalog based on the original VLA-COSMOS 3,GHz 0farcs75 resolution mosa