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Neutral Hydrogen Gas in Star Forming Galaxies at z=0.24 Philip Lah Frank Briggs (ANU) Jayaram Chengalur (NCRA) Matthew Colless (AAO) Roberto De Propris (CTIO) Michael Pracy (ANU) Erwin de Blok (ANU)
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Background
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Star Formation Rate Subaru Field Hα Spectroscopy Hα Narrow Band Imaging UV (with no dust correction)
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HI redshift Zwaan et al. 2005 HIPASS HI 21cm Rao et al. 2006 Prochaska et al. 2005
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HI look back
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HI 21cm Emission at High Redshift
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Previous highest redshift HI Westerbork Synthesis Radio Telescope (WSRT) Netherlands Abell 2218 z = 0.18 integration time 36 days, Zwaan et al. 2001 Very Large Array (VLA) Abell 2192 z = 0.1887 integration time ~80 hours, Veheijen et al. 2004
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Giant Metrewave Radio Telescope
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GMRT Antenna Positions
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GMRT Collecting Area 30 dishes of 45 m diameter GMRT Collecting Area 21 × ATCA 15 × Parkes 6.9 × WSRT 3.6 × VLA
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Method of HI Detection RA DEC Radio Data Cube pick out HI signal using optical redshifts coadd faint signals to make measurement
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The Subaru Field - H emission galaxies
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Subaru Field RA DEC 24’ × 30’ Fujita et al. 2003 narrow band imaging - H emission flux used 2dF to get optical redshifts
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Subaru Field Data GMRT Obs Time Frequency Observed z Look Back Time RMS per channel 80.5 hours 1150 MHz 0.242.8 Gyr ~130 Jy Primary Beam Size ResolutionChannel Width Number of Channels ~29’ ~3’’32.6 kms -1 2 × 128
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Subaru Galaxies - B magnitude Thumbnails 10’’ sq Ordered by H luminosity
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Subaru Galaxies - redshifts Thumbnails 10’’ sq Ordered by H luminosity
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Redshift histogram Subaru Narrow Band Filter FWHM (120 Å) GMRT HI freq range 2dF (& AAOmega) redshifts
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HI spectrum all 121 redshifts Neutral Hydrogen measurement M HI = (1.47 ± 0.89) ×10 9 M
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HI redshift mine all used the Fujita et al. 2003 H Luminosity function for volume calculation comparable error to low z DLA measurements but required less observing effort (no need lots of HST time)
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Radio Continuum in the Subaru Field
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Deepest GMRT Image Sub field 12’ × 12’ RMS ~ 16 Jy several hundred continuum sources some with optical counterparts
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Sullivan et al. 2003 Sullivan et al. 2001 H Luminosity vs. 1.4 GHz Luminosity & UV Luminosity vs. 1.4 GHz Luminosity
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Halpha vs. RC line from Sullivan et al. 2001 10’ × 10’
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Conclusions measured the neutral gas density at z=0.24 with similar accuracy to the DLA method – with plenty of room for improvement made the current deepest GMRT continuum image the H emission - radio continuum correlation for star forming galaxies seems to hold true at z=0.24
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The End
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Additional Slides
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HI redshift mine all taking into account narrow band (H ) filter shape – brighter galaxies will be seen over a larger volume
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Model no error
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model
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UV Plane
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Fuzzy RC Integrated Flux = 17.035 0.077 mJy
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Fuzzy B galaxy UGC 05849 at redshift z=0.026045
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