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Exploring Low Frequencies in Cosmic Evolution and High-Redshift Radio Sources

This study delves into the significance of low-frequency observations in understanding cosmic evolution, emphasizing the role of neutral hydrogen (H0) and high-redshift phenomena. It explores technologies like multi-beaming and their applications in detecting all-sky transients and cosmic rays. Key insights include the relationships between redshift, cosmic star formation rates, and the comprehensive data from radio sources such as HIPASS. By analyzing the dynamics of gas halos and quasar density, this research aims to illuminate the intricate history of the universe from the Big Bang to present-day formations.

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Exploring Low Frequencies in Cosmic Evolution and High-Redshift Radio Sources

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Presentation Transcript

  1. what good are low frequencies? • HI, neutral hydrogen, H0, atomic hydrogen • high redshifts and early times…. USS, GPS, … • “enabling technologies” …multi-beaming, all-sky transients,…, the highest energy cosmic rays…

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

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

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

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

  6. cosmic density Wg of Neutral Gas extent of metal-rich gaseous halos co-moving number density of bright Quasars Cosmic Star Formation Rate history: the Madau Plot 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 Cosmic Evolution Indicators Redshift

  7. frequency 1420 500 250 MHz Passive relaxation Violent accretion Cosmic Evolution Indicators Redshift

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

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

  10. source centroid as fnct of Frequency SKA map emission ? 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 DLA absorption lines No UV continuum

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

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

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