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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,

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Presentation on theme: "What good are low frequencies? HI, neutral hydrogen, H 0, atomic hydrogen high redshifts and early times…. USS, GPS, … “enabling technologies” …multi-beaming,"— Presentation transcript:

1 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…

2 FREQ. GHz FREQ MHz 50 100 200 1000 Z = 4 Gigahertz Peak Sources: young radio sources ???

3 .…. ionized…… re-re-ionized re-ionized Big Bang Nucleosynthesis

4 HI HI HI HI HI 70 MHz ………………..180 MHz

5 damped Lyman-  abs-lines 21cm Line Studies (HIPASS)

6 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

7 Violent accretion accretion Passive relaxation relaxation CosmicEvolutionIndicators Redshift 1420 500 250 MHz frequency

8 3C196- G1 z = 0.437 HST image (Ridgway & Stockton) 3” Cohen et al

9 Double Lobed Radio Source Radio spectrum at 988 MHz Westerbork (Briggs, deBruyn, Vermeulen) 300 km/s

10 source centroid as fnct of Frequency map emission ? SKA map absorption ?

11 new GMRT Kanekar & Chengalur 988 MHz

12 high redshift radio galaxies TNR J2254+1857 TNR J1402-1510

13 Radio galaxy spectra No UV continuum No DLA absorption lines

14 Molonglo Telescope: SKAMP III frequency coverage sensitivity RFI rejection VLBI to resolve source

15 the Molonglo challenges: broadband line feeds 96 station correlator Defence HQ 3 km away ?!?!


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