Far-Infrared To(Sub)millimeter Study Of High Redshift Galaxies In The COSMOS Field

In this thesis I present a "super-deblended" far-infrared to(sub)millimeter pho-tometric catalog in the Cosmic Evolution Survey(COSMOS)field,that we prepared following the "Super-deblending" techniques recently developed in GOODS-North,but with key adaptations tailored to this survey field that is much larger(?2 deg2)albeit with shallower supporting data for prior selection.We obtain point spread function(PSF)fitting photometry at fixed prior positions including 88,008 galaxies detected in either VLA 1.4 GHz,3 GHz and/or MIPS 24 ?m images.By adding a specifically carved mass-selected sample(with an evolving stellar mass limit tuned from GOODS-North observations),a highly complete prior sample of 194,428 galaxies is achieved for deblending FIR/(sub)mm images.We performed "active" removal of non relevant priors at all FIR/(sub)mm bands using spectral energy distribution(SED)fitting and redshift information.In order to cope with the shallower COSMOS data(especially in Herschel PACS)we introduce here new,more detailed procedures for subtracting the flux of faint non-fitted priors from the maps and for accounting for the uncertainty of this step.The resulting photometry at each band(including data from Spitzer,Her-schel,SCUBA2,AzTEC,MAMBO and VLA 3 GHz and 1.4 GHz)displays well be-haved quasi-Gaussian uncertainties,that are calibrated from Monte Carlo simulations and tailored to observables(crowding,residual maps).Based on this work,i)we obtained 11,220 galaxies that are significantly detected over the 100-1200 ?m range with reliable photometry,extending all the way to z?7.ii)we conservatively selected a sample of 85 solid high redshift candidates at z>4 with significant detections at FIR/(sub)mm wavelengths,often with securely identi-fied counterparts from radio and/or Spitzer/IRAC.Redshifts of four candidates are spectroscopically confirmed by our ALMA observations.This sample provides us a chance to statistically investigate the first generation of vigorous starburst galaxies(SFRs?1000M? yr-1)in the early Universe,?)We found that the most distant X-ray-detected cluster known to date,Cl J1001 at z = 2.5 hosts a strong overdensity of radio sources,demonstrating prospects for future deep and wide-area radio surveys to dis-cover large samples of the first generation of forming galaxy clusters.iv)By searching radio overdensity in the whole COSMOS field,we selected two candidates of galaxy cluster at z?3 that are excellent objects for studying formation and evolution of mas-sive structures in the early Universe.