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The Evolution of Stars and Gas in Galaxies: PhD Midterm Philip Lah A journey with noise and astrometry
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Supervisor: Frank Briggs Supervisory Panel: Erwin de Blok (RSAA) Jayaram Chengalur (National Centre for Radio Astrophysics, India) Matthew Colless (Anglo-Australian Observatory) Roberto De Propris (Cerro Tololo Inter-American Observatory, Chile)
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Those that deserve special mentions: Brian Schmidt Agris Kalnajs Michael Pracy Tony Martin-Jones Scott Croom (AAO) & Rob Sharp (AAO) Nissim Kanekar (NRAO)
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Goal of PhD to relate the star formation rate, the stellar mass and the mass in neutral hydrogen gas in galaxies as they evolve to examine galaxy evolution over last 4 Gyr, (a third of the age of the universe, z~0.4) to study galaxies in a variety of different environments UNIQUE PART to study galaxy properties in the same systems – optically selected galaxies
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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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HI emission HI – single atom of hydrogen – radiation from an excited state were proton & electron have the same spin - 10 million year half life Assuming an optically thin neutral hydrogen cloud M HI * = 6.3 ×10 9 M (HIPASS, Zwaan et al. 2005)
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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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Observational Targets
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Table of Targets TargetTypez Look Back Time GMRT Obs Time Subaru Field field galaxies with H emission 0.242.8 Gyr80.5 hours Abell 370 cluster and surroundings 0.374.0 Gyr70 hours Cl0024+1654 cluster and surroundings 0.394.2 Gyr18 + 45 hours
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Galaxy Cluster Abell 370
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RA DEC 27’ × 27’ Cluster Centre
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Galaxy Cluster Abell 370 RA DEC ~3’ × 3’
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HI Abell 370 33 literature redshifts but σ z ≥ ± 300 kms -1 Upper limit M HI = 1.3 M HI * with 95% confidence
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Galaxy Cluster Abell 370 need more redshifts for reasonable analysis the plan is to use WFI on SSO 40 inch for imaging – Mike Pracy took some data last year and hopefully take more this year hopefully use AAOmega for spectroscopic follow- up in October/November 2006 also made improvements to my data reduction methods so redo reduction
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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 We used 2dF to get redshifts
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SDF positions GMRT beam 10% level GMRT beam 50% level Blue Points Subaru galaxies Red Points NVSS Radio Continuum Sources
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SDF uv coverage Subaru Field is equatorial
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Image of Dirty Beam image 7’ × 7’ radio equivalent of optical point spread function
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Self Calibration
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Deepest GMRT Image Field 10 12’ × 12’ RMS ~ 16 Jy
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Sad cont sources From AIPS auto detection routine - SAD Blue > 5 mJy Red > 1 mJy Black > 0.32 mJy Grey > 80 Jy RMS ~ 16 Jy Subaru Field boundary
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Continuum Images Thumbnails 20’’ sq
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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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Astrometry need optical and radio positions to agree to a high level of precision shift in radio data – corrected by comparing with FIRST continuum source positions optical data – PROBLEM coordinates that I had been given for the Subaru galaxies rounded to the 5 th decimal place before converting to degrees/hours, minutes, seconds format eg. 10.56479302 10.56479 10h 33m 53.24s
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Position change Rounding error: 0.18’’ DEC 2.7’’ RA PROBLEMS 2dF fibre diameter is 2’’ many galaxies smaller than 2’’
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Radio Continuum of the Subaru Galaxies
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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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Subaru Galaxies - B magnitude Thumbnails 10’’ sq Ordered by H luminosity
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Subaru Galaxies – Continuum Thumbnails 10’’ sq
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Halpha vs. RC line from Sullivan et al. 2001
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Neutral Hydrogen in the Subaru Galaxies
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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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2dF spectrum good good spectrum
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2dF spectrum poor not so great spectrum
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Redshift histogram Subaru Narrow Band Filter FWHM (120 Å) GMRT HI freq range 112 redshifts in GMRT data
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Galaxy Sizes Thumbnails 10’’ sq Ordered by H luminosity Variety of sizes – measured size at 25 th mag arcsec -2 isophote
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Diameter HI unsmoothed beam FWHM ~3’ (10 kpc) smoothed beam FWHM ~5.3’ (20 kpc) smoothed beam FWHM ~8.0’ (30 kpc)
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HI spectrum all 112 redshifts Neutral Hydrogen measurement M HI = 0.071 0.12 M HI *
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HI spectrum bright Log H Luminosity > 41 erg s -1 36 redshifts Neutral Hydrogen measurement M HI = 0.57 0.26 M HI *
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HI spectrum faint Log H Luminosity 40.4 erg s -1 33 redshifts Neutral Hydrogen measurement M HI = 0.31 0.19 M HI *
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HI spectrum mid 40.4 < Log H Luminosity 41 erg s -1 43 redshifts Neutral Hydrogen measurement M HI = 0.44 0.20 M HI *
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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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Future Work: Galaxy Cluster Cl0024+1654
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Galaxy Cluster Cl0024+1654 RA DEC 21’ × 21’ Cluster Centre
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Galaxy Cluster Cl0024+1654 RA DEC ~1’ × 1’
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Cl0024+1654 Data HST imaging 2181 galaxies with morphologies of which 195 spectroscopically confirmed cluster members (Treu et al. 2003) H α narrow band imaging with Subaru star formation rates (Kodama et al. 2004) 296 literature redshifts within HI frequency limits of the GMRT observation (Cszoke et al. 2001) 18 + 45 hours GMRT observations
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Cl0024 positions GMRT Beam 50% level
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Cl0024 z slice GMRT HI freq limits
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PhD Timetable of Completion Rest of 2006: finish analysis of the Subaru Field (to be completed by the end of August 2006) analysis of galaxy cluster Cl0024+1652 (analysis to be finished by January 2007) optical imaging of galaxy cluster Abell 370 using SSO 40 inch and AAOmega follow-up to get redshifts – Mike Pracy doing much of this but I will be involved 2007: complete analysis of galaxy cluster Abell 370 (to be finished no later than June 2007) write up my thesis throughout 2007 finish between September 2007 & March 2008 (3½ - 4 year mark)
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The End
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Additional Slides
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The UV Plane
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Model no error
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model
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B mag vs. Halpha Lum
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UV Plane
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Stellar Mass Density Dickenson et al. 2003
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HI spectrum bright faint M HI = 0.41 0.15 M HI *
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Method of HI Detection individual galaxies HI 21cm emission below radio observational detection limits large sample of galaxies with known positions & precise redshifts (from optical observations) coadd weak HI signals isolated in position & redshift (velocity) space measure integrated HI signal – total HI mass of whole galaxy population – can calculate the average HI galaxy mass
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Galaxy Cluster Abell 370 originally started working on this data in 3 month project – worked on to learn radio astronomy 42 literature redshifts for Abell 370 cluster members 33 are usable – large error in σ z ≥ ± 300 kms -1 (from Soucail et al. 1988 )
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Galaxy Environment galaxy environment cluster, cluster outskirts and the field density - morphology relation density - star formation relation density - neutral hydrogen relation Cause of density relations?
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