1 / 58

NEUTRAL HYDROGEN

NEUTRAL HYDROGEN. Frank Briggs RSAA and ATNF. z = 8. z = 0. damped Lyman- a abs-lines. 21cm Line Studies (HIPASS). 20. -2. N >2x10 cm. Lyman a forest. Metal lines. HI. DLA. Quasar Absorption lines. Wavelength (Angstroms). HI D.L.A.

holland
Download Presentation

NEUTRAL HYDROGEN

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NEUTRAL HYDROGEN Frank Briggs RSAA and ATNF z = 8 z = 0

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

  3. 20 -2 N >2x10 cm Lyman a forest Metal lines HI DLA Quasar Absorption lines Wavelength (Angstroms)

  4. HI D.L.A. SiII CII SiII FeII AlII OI/SiII SiIV CIV Quasar (all DLAs have metal lines)

  5. …bathe HI cloud in photoionizing radiation… Photons DE > 13.6 eV

  6. …bathe HI cloud in photoionizing radiation… ?? minimum thickness of skin before becomes self-shielding ??

  7. 17 -2 N >3x10 cm HI …bathe HI cloud in photoionizing radiation… optical depth t > 1 for DE ~ 13.6 eV photons note: t< 1 … transparent… hard to heat!

  8. transitions from ground state are absorbed Photons DE > 13.6 eV are absorbed Energy Levels in Hydrogen Optically thick at the Lyman limit Optically thick in the Lyman continuum E = 0 Energy Ground State

  9. Energy Levels in Hydrogen Optically thick in the Lyman continuum E = 0 BUT HI layer is transparent to all other wavelengths shorter than the Lyman limit Energy Ground State

  10. Ionization by ambient starlight with l > 912 Angstrom E = 0 Energy Ground State H He C N O Na Mg Al Si Ca Ti Cr Mn Fe Zn

  11. Lyman a forest Metal lines DLA Quasar Absorption lines Wavelength (Angstroms)

  12. Metal lines LL Quasar Absorption lines Lyman a forest DLA

  13. Quasar Absorption lines • thoroughly developed statistics !!! for Lyman a and metal lines… (ordinary Galaxies (whatever is common… is most likely to intervene by chance)

  14. DLA CIV MgII/ Lyman limit (CII, FeII, SiII, …) Relative interception cross sections … Z=3 Ly break galaxy

  15. HI Column density distribution function Number of interceptions in range: N to N+dN NHI = NH (nHI / nH) f(N) dN per unit z Ionization fraction ~10-3 ? tLL > 1 Lya forest IGM DLA CIV Petijean etal 1993 -10 -15 Log f(NHI) -20 12 14 18 20 22 Log NHI

  16. HI Column density distribution function -3/2 f(N)dN ~ N dN /unit Z M~Nf(N)dN HI DLA M/Log Interv~N f(N) 2 HI +1/2 ~N Petijean etal 1993 -10 -15 Log f(NHI) -20 12 14 18 20 22 Log NHI

  17. DLA CIV MgII/ Lyman limit (CII, FeII, SiII, …) Relative interception cross sections … What are these things??? Z=3 Ly break galaxy (tough to image)pin

  18. nearby Neutral gas disksanalogs to high Z DLAs ??? Optical + Radio

  19. Extended, low-column density gas = analog of LymanLimit/MgII CIV is the lower density material ??

  20. Square Kilometre Array

  21. ARRAY Simple antenna “elements” “Array” “Station”

  22. Sensivity depends on collecting area Angular resolution ~ l/D D

  23. Sensivity depends on collecting area Angular resolution ~ l/D D

  24. ESO VLTI ALMA VLA

  25. 6th ATNF Synthesis Imaging Workshop “Synthesis Imaging from Centimetre to Millimetre Wavelengths” 12-16 May 2003 at Narrabri NSW www.atnf.csiro.au/synthesis

  26. ARRAY Simple antenna “elements” “Array” “Station”

  27. SKA Design “Magic Carpet”

  28. Eggs on Legs

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

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

  31. source centroid as fnct of Frequency SKA map emission ? map absorption ?

  32. new GMRT Kanekar & Chengalur 988 MHz

  33. high redshift radio galaxies TNR J2254+1857 TNR J1402-1510

  34. Radio galaxy spectra No DLA absorption lines No UV continuum

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

  36. 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

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

  38. If neutral fraction nHI > ~10-3 nHI +nHII Cut off from view of optical wavelengths !!!

  39. Gnedin’s simulation of Reionization: http://casa.colorado.edu/~gnedin/GALLERY/ log(mean intensity of ionizing flux) log(Neutral fraction) log(density) log T

  40. re-ionized re-re-ionized .…. ionized……

  41. MAP

  42. MAP Result Z = 17 + 4 ??? Rules out WDM

  43. 70 MHz ………………..180 MHz

  44. 20 mK Global Signal…

  45. “The Z=20 Expt” JR, FB, et al

More Related