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what good are low frequencies? HI, neutral hydrogen, H 0, atomic hydrogen high redshifts and early times…. USS, GPS, … “enabling technologies” …multi-beaming, all-sky transients,…, the highest energy cosmic rays…
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FREQ. GHz FREQ MHz 50 100 200 1000 Z = 4 Gigahertz Peak Sources: young radio sources ???
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.…. ionized…… re-re-ionized re-ionized Big Bang Nucleosynthesis
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HI HI HI HI HI 70 MHz ………………..180 MHz
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damped Lyman- abs-lines 21cm Line Studies (HIPASS)
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CosmicEvolutionIndicators Redshift 0 1 2 3 4 5 co-moving number density of bright Quasars Cosmic Star Formation Rate history: the Madau Plot 0 1 2 3 4 5 extent of metal-rich gaseous halos cosmic density g of Neutral Gas 0 1 2 3 4 5
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Violent accretion accretion Passive relaxation relaxation CosmicEvolutionIndicators Redshift 1420 500 250 MHz frequency
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3C196- G1 z = 0.437 HST image (Ridgway & Stockton) 3” Cohen et al
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Double Lobed Radio Source Radio spectrum at 988 MHz Westerbork (Briggs, deBruyn, Vermeulen) 300 km/s
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source centroid as fnct of Frequency map emission ? SKA map absorption ?
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new GMRT Kanekar & Chengalur 988 MHz
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high redshift radio galaxies TNR J2254+1857 TNR J1402-1510
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Radio galaxy spectra No UV continuum No DLA absorption lines
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Molonglo Telescope: SKAMP III frequency coverage sensitivity RFI rejection VLBI to resolve source
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the Molonglo challenges: broadband line feeds 96 station correlator Defence HQ 3 km away ?!?!
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