Mock Surveys of the Sub-millimetre Sky

Transcription

1 Mock Surveys of the Sub-millimetre Sky William Cowley Supervisors: Carlton Baugh, Cedric Lacey, Shaun Cole DEX-X: Thurs 9th Jan

2 Outline Sub-millimetre Galaxies Observational Motivation Angular resolution Field-to-field variations Theoretical Model GALFORM Dust model Creating lightcones Results and Future Work ALMA observing sub-mm galaxy LESS J credit:naoj

3 Sub-millimetre Galaxies (SMGs) First detected by SCUBA/JCMT in late 9s Luminous, high redshift (z ), dusty galaxies L IR L = SFR - M yr Single-dish sub-mm surveys: Coarse angular resolution ( FWHM) Pencil-beam areas (.7 deg ) 87µm LESS (" FWHM,.5 deg ) map Weiss et al 9 ALMA (.5" FWHM) observation of LABOCA (" FWHM) source Karim et al

4 Observational Motivation Angular resolution: Some " blended sources break up into multiple fainter.5" sources, affecting observed number counts Field-to-field variations: % prob of LH and UDS samples being drawn from same population Fraction per bin.5... Lockman Hole. mm (LH, robust IDs) 85 µm (LH Dye8 robust IDs) 85 µm (LH Dye8, all IDs) 85 µm (LH Schael robust IDs) 85 µm (LH Schael all IDs) K-S AzTEC - Dye8:.7% K-S AzTEC - Schael: 6%...5 UDS. mm (UDS, robust IDs) 85 µm (UDS Clements8) 85 µm (UDS Schael robust IDs) 85 µm (UDS Schael all IDs) Fraction per bin... K-S AzTEC - Clements8: 7% K-S AzTEC - Schael: 5% Karim et al Michalowski et al.. 5 Redshift

5 GALFORM Durham Semi-Analytic Galaxy Formation Model COSMOLOGICAL MODEL Ω, Λ, σ, h, P(k) 8 Galaxy formation and evolution is complex Semi-Analytic Models (SAMs) use simplified descriptions of physical processes Ab initio, physically motivated method to populate N-body simulations with galaxies, with minimal computational expense Parameters constrained by requiring local galaxy population to be reproduced DISK SIZES DARK MATTER HALOS MERGER TREES STRUCTURE GAS COOLING GALAXY MERGERS DISK FORMATION SPHEROID FORMATION STAR FORMATION BURSTS & FEEDBACK CHEMICAL EVOLUTION STELLAR POPULATIONS DUST EXTINCTION OBSERVABLE GALAXY PROPERTIES SPHEROID SIZES Adpated from Cole et al () 5

6 Lacey Model Features of the Model Millennium N-body simulation (WMAP-7 cosmology) AGN feedback Improved star formation treatment Successfully predict sub-mm observations and present day (z = ) luminosity function Top-heavy IMF (x = ) in starburst galaxies Bursts triggered by disk instabilities and galaxy mergers Multi-wavelength predictions K-band luminosity function Lyman-break luminosity function Lacey et. al. in prep 6

7 Lacey Model Features of the Model Millennium N-body simulation (WMAP-7 cosmology) AGN feedback Improved star formation treatment Successfully predict sub-mm observations and present day (z = ) luminosity function Top-heavy IMF (x = ) in starburst galaxies Bursts triggered by disk instabilities and galaxy mergers Multi-wavelength predictions K-band luminosity function Lyman-break luminosity function Lacey et. al. in prep 6

8 Galform Dust Model Two component dust medium: Molecular clouds (in which stars form) + Diffuse ISM Dust in thermal equilibrium with stellar radiation emits as modified blackbody: L dust λ = πκ d B λ (T d )M d Dust temperature calculated self consistently Granato et. al. 7

9 Creating Lightcones Merson et al log N(>S) (deg ) 6 5 Integral Lightcone (. deg ) Knudsen+ 8 Chen+ - - N-body simulation volume tiled to fill lightcone volume Cone geometry assigned Galaxy positions interpolated Preserves correlation function K -correction interpolated C.f. integral method of calculating number counts/redshift distribution d N d ln S = νdz dn d ln L ν dv dz 8

10 Creating Lightcones Merson et al log N(>S) (deg ) 6 5 Area of survey means some rare objects are missed Integral Lightcone (. deg ) Knudsen+ 8 Chen+ - - N-body simulation volume tiled to fill lightcone volume Cone geometry assigned Galaxy positions interpolated Preserves correlation function K -correction interpolated C.f. integral method of calculating number counts/redshift distribution d N d ln S = νdz dn d ln L ν dv dz 8

11 Creating Lightcones Merson et al dn(>s)/dz (deg ) 5 5 Integral z 5=.9 Lightcone (. deg ) z 5=.8 S 85 >.mjy 5 6 Redshift N-body simulation volume tiled to fill lightcone volume Cone geometry assigned Galaxy positions interpolated Preserves correlation function K -correction interpolated C.f. integral method of calculating number counts/redshift distribution d N d ln S = νdz dn d ln L ν dv dz 8

12 Creating Lightcones Merson et al dn(>s)/dz (deg ) 5 5 Integral z 5=.9 Lightcone (. deg ) z 5=.8 S 85 >.mjy At high redshifts the lightcone interpolation scheme does not reproduce the instrinsic evolution of the luminosity function 5 6 Redshift N-body simulation volume tiled to fill lightcone volume Cone geometry assigned Galaxy positions interpolated Preserves correlation function K -correction interpolated C.f. integral method of calculating number counts/redshift distribution d N d ln S = νdz dn d ln L ν dv dz 8

13 Mock Surveys: Field-to-field Variance.5 deg surveys log N(>S) (deg ) percentile Integral Lightcone (.5 deg ) Knudsen+ 8 Chen+ - - dn(>s)/dz (deg ) 5 5 mean median z 5=.9 z 5=.8 S 85 >.mjy 5 6 Redshift 9

14 Mock Surveys: Field-to-field Variance.5 deg surveys log N(>S) (deg ) percentile Integral Lightcone (.5 deg ) Knudsen+ 8 Chen+ - - dn(>s)/dz (deg ) 5 5 Distribution of individual survey redshift means/medians mean median z 5=.9 z 5=.8 S 85 >.mjy 5 6 Redshift 9

15 Mock Surveys: Field-to-field Variance.5 deg surveys log N(>S) (deg ) percentile Integral Lightcone (.5 deg ) Knudsen+ 8 Chen+ - - dn(>s)/dz (deg ) Simpson+ (ALESS) mean median z 5=. z 5=. S 85 >5mJy 5 6 Redshift 9

16 Mock Surveys: Angular Resolution I Creating Mock Catalogues η (deg) mjy/beam Lightcone: RA, DEC and S 85µm >.mjy Pixelate (."." pixels) Convolve 5" FWHM SCUBA Re-pixelate (" " pixels) Add white noise ( mjy) Zero mean Convolve with matched filter g(q) = s (q)/j(q) s(q) /J(q)d q ɛ (deg) e.g. Laurent et al 5 Source Extraction: Search for hottest pixel in map and subtract off PSF

17 Mock Surveys: Angular Resolution I Creating Mock Catalogues η (deg) mjy/beam Lightcone: RA, DEC and S 85µm >.mjy Pixelate (."." pixels) Convolve 5" FWHM SCUBA Re-pixelate (" " pixels) Add white noise ( mjy) Zero mean Convolve with matched filter g(q) = s (q)/j(q) s(q) /J(q)d q ɛ (deg) e.g. Laurent et al 5 Source Extraction: Search for hottest pixel in map and subtract off PSF

18 Mock Surveys: Angular Resolution I Creating Mock Catalogues η (deg) mjy/beam Lightcone: RA, DEC and S 85µm >.mjy Pixelate (."." pixels) Convolve 5" FWHM SCUBA Re-pixelate (" " pixels) Add white noise ( mjy) Zero mean Convolve with matched filter g(q) = s (q)/j(q) s(q) /J(q)d q ɛ (deg) e.g. Laurent et al 5 Source Extraction: Search for hottest pixel in map and subtract off PSF

19 Mock Surveys: Angular Resolution I Creating Mock Catalogues η (deg) mjy/beam ɛ (deg) Lightcone: RA, DEC and S 85µm >.mjy Pixelate (."." pixels) Convolve 5" FWHM SCUBA Re-pixelate (" " pixels) Add white noise ( mjy) Zero mean Convolve with matched filter g(q) = e.g. Laurent et al 5 s (q)/j(q) s(q) /J(q)d q Source Extraction: Search for hottest pixel in map and subtract off PSF

20 Mock Surveys: Angular Resolution I Creating Mock Catalogues η (deg) z=.67 z=.67 z= z=.588 mjy/beam z=.9 z= 5. z=.87 z=.6 z=.79 z=.8 z=.5 z=.6 z=.766 z=.79 Lightcone: RA, DEC and S 85µm >.mjy Pixelate (."." pixels) Convolve 5" FWHM SCUBA Re-pixelate (" " pixels) Add white noise ( mjy) Zero mean Convolve with matched filter g(q) = s (q)/j(q) s(q) /J(q)d q ɛ (deg) e.g. Laurent et al 5 Source Extraction: Search for hottest pixel in map and subtract off PSF

21 Mock Surveys: Angular Resolution II Number Counts Karim+ (ALESS.5 ) Weiss+ 9 (LESS ) Knudsen+ 8 Chen+ log N(>S) (deg ) log N(>S) (deg ) 9- percentile Lightcone (.5 deg ) 5 beam 7.5 beam 5 beam beam

22 Mock Surveys: Angular Resolution II Number Counts Karim+ (ALESS.5 ) Weiss+ 9 (LESS ) Knudsen+ 8 Chen+ log N(>S) (deg ) log N(>S) (deg ) 9- percentile Lightcone (.5 deg ) 5 beam 7.5 beam

23 Mock Surveys: Angular Resolution II Number Counts Karim+ (ALESS.5 ) Weiss+ 9 (LESS ) Knudsen+ 8 Chen+ log N(>S) (deg ) log N(>S) (deg ) 9- percentile Lightcone (.5 deg ) 5 beam 5 beam

24 Mock Surveys: Angular Resolution II Number Counts Karim+ (ALESS.5 ) Weiss+ 9 (LESS ) Knudsen+ 8 Chen+ log N(>S) (deg ) log N(>S) (deg ) 9- percentile Lightcone (.5 deg ) 5 beam beam

25 Mock Surveys: Angular Resolution II Number Counts Karim+ (ALESS.5 ) Weiss+ 9 (LESS ) Knudsen+ 8 Chen+ log N(>S) (deg ) log N(>S) (deg ) 9- percentile Lightcone (.5 deg ) 5 beam 7.5 beam 5 beam beam

26 Summary and Future Work Summary SMG observations are sensitive to field-to-field variations Angular resolution of single-dish telescopes can skew observed number counts Future Work Properties of the blended SMG population multiple fraction physical (un)associations Comparison of multi-wavelength surveys Predictions for lensed vs. un-lensed SMG populations