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A 1200μm MAMBO Survey of GOODS-N

A 1200μm MAMBO Survey of GOODS-N. - A new population of submillimetre drop-out galaxies; hunting for z > 4 SMGs. Thomas R. Greve (DARK Cosmology Centre, Niels Bohr Institute, Copenhagen). IRAM 30m. MAMBO.

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A 1200μm MAMBO Survey of GOODS-N

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  1. A 1200μm MAMBO Survey of GOODS-N - A new population of submillimetre drop-out galaxies; hunting for z > 4 SMGs Thomas R. Greve (DARK Cosmology Centre, Niels Bohr Institute, Copenhagen) IRAM 30m MAMBO Collaborators:Alexander Pope, Colin Borys, Douglas Scott, Rob Ivison, Frank Bertoldi July 2010, Windsor, UK

  2. Other results from the MAMBO/GOODS-N Survey New constraints on the extragalactic background light at 1mm (Penner et al. in press) 1200μm stacking analysis of NIR-selected galaxies in GOODS-N (Greve et al. in prep)

  3. JCMT/SCUBA The Submm Sky Hughes et al. (1998) Submillimeter-selected Galaxies (SMGs):A new significant population of high-z dust-enshrouded starburst galaxies -- previously undetected at optical wavelengths (Smail, Ivison, Blain, Hughes, Dunlop, Barger…. 1997-1999) Space densities, star formation rates, gas & stellar masses consistent with them being the long-sought for progenitors of today’s ellipticals and spheroids

  4. Submm/mm Magic Submm: a unique tracer of dust-obscured SF at z > 1 LIR = 1x1013L Radio Submm

  5. What is the nature of the radio un-identified SMGs (20-30%)? • Radio-ID’ed SMGs have a median redshift of 2.2 Chapman et al. (2003) The SMG redshift distribution • ~80% of SMGs are identified in deep radio maps • Radio IDs essential for obtaining spectroscopic redshifts Ivison et al. (2002)

  6. z > 4 SMG candidates LH1200.2 Also Detected by AzTec at 1.1mm MAMBO 1200um SCUBA 850um Scott et al. (2002) Greve et al. (2004) Eiichi Egami et al. 3.6m 4.5m 5.8m 8.0m 24m R-band

  7. z > 4 SMG candidates IRAM Plateau de Bure sub-arcsecond interferometry at 1mm of 3 bright (S1200m > 3.5mJy) MAMBO sources in the NTT deep fieldNo near-IR counterpart down to KS > 21.9mag Dannerbauer et al. (2002)

  8. z > 4 SMG candidates GN850.10: z ≈ 4 Wang et al. (2007) HDF850.1: z ≈ 4.1 Dunlop et al. (2004) Dannerbauer et al. (2008)

  9. z > 4 SMG candidats SMA sub-arcsecond interferometry at 0.89mm of 7 very bright (S1100m > 6.8mJy) AzTec sources (i.e. selected at 1.1mm) in the COSMOS field5 radio-dim (S1.4GHz < 41Jy) likely at z>>3 X X X X X Younger et al. (2007)

  10. Eales et al. (2003) SMGs QSOs =2: Td = 20-70K Eales et al. (2003): the 850-/1200-um flux ratio is sensitive to redshift (beyond z=3). SCUBA photometry of MAMBO sources  tentative evidence of z>4 or peculiar dust properties Need for an unbiased comparison of SCUBA and MAMBO maps =1.0: Td = 20-70K The 850-/1200-m flux ratio

  11. IRAM 30m, MAMBO The mm view of the sky millimeter-selected Galaxies:Almost parallel to SCUBA, the MAMBO camera on the IRAM 30m Telescope in Granada, Spain, surveyed extragalactic fields at 1200m. They confirmed the existence of a new population of high-z dust-enshrouded starburst galaxies (Bertoldi et al. 2003; Greve et al. 2004) The great hope: MAMBO, operating at >1mm wavelengths, would probe the unseen high-z (z>4) tail of the SCUBA population!

  12. GOODS-N & multi-wavelength coverage VLA HST Spitzer Williams et al. (1995) Dickinson et al. (2006) Richards et al. (2000)Alexander et al. (2006) Chandra IRAM 30m, MAMBO 10x16 sq. arcmin field. Centered on HDF-N: 12:36:55 +62:14:16 (2000.0) Giavalisco et al. (2004)

  13. Borys et al. (2003); Pope et al. (2005, 2006) The 850μm SCUBA HDF-N Supermap(Borys, Pope et al. 2004, 2005, 2006) • A compilation of all existing SCUBA data in GOODS-N • Highly non-uniform noise! 4.0 3.0 0.5 35 sources extracted after Bayesian flux deboosting 2.0

  14. The 1200m MAMBO GOODS-N map S/N map Noise map Greve et al. (2008) 30 sources extracted after Bayesian flux deboosting

  15. The 1200m MAMBO GOODS-N map S/N map • Deboosted samples: SCUBA ID frac = 16% MAMBO ID frac = 18% Noise map Greve et al. (2008) 30 sources extracted after Bayesian flux deboosting

  16. S/N ~ 6 S/N ~ 3 Two samples: ‘1200m-blank’ SCUBA sources: 16 ‘850m-blank’ MAMBO sources : 12 Stack: 1) fluxes at positions, or 2) peak fluxes within r=7” aperture Stacking analysis - I

  17. Stacking analysis - II Two samples: ‘1200m-blank’ SCUBA sources: 16 ‘850m-blank’ MAMBO sources : 12 Compare S/N distributions of the two samples with the overall S/N distributions of the SCUBA and MAMBO maps PKS = 0.11 PKS = 0.001

  18. (Td=20K, =1.5) z=1.5 z=5 (Td=10K, =1.0) Eales et al. (2003) Greve et al. (2004)Younger et al. (2007) Greve et al. (2008) SCUBA Drop-Out galaxies (SDOs)

  19. The 1200μm MAMBO survey of GOODS-N Suggest that ‘850m-blank’ MAMBO sources are at z > 4 or have cold/peculiar SEDs • Results: • ‘1200m-blank’ SCUBA sources are statistically detected at 850m (S/N > 6) • ‘850m-blank’ MAMBO sources not statistically detected at 1200m (S/N < 3) • ‘850m-blank’ MAMBO sources have significantly lower 850m/1200m flux ratios than ‘1200m-blank’ SCUBA sources

  20. The 1200μm MAMBO survey of GOODS-N • Speculations: • Adopting <z>~5 for SDOs and adopting (Td=20K, =1.5) and S850μm=1.8- 3.5mJy: LFIR = (3-5) x 1012L and Md = (3-6) x 109M • The presence of such massive systems at z~5 (~1Gyr after the Big Bang) has implications for understanding of galaxy formation and evolution at the high-mass end • SDOs may be good candidates for systems collapsing in a monolithic (Eggen, Lynden-Bell & Sandage 1962) very early on in the Universe’s history • The presence of large amounts of dust only ~1Gyr after the Big Bang suggest that SNeII is the main dust producing mechanism (not evolved stars)

  21. Spectroscopically confirmed z > 4 SMGs Discovery: a z=4.76 submm-selected source not associated with a QSO Seem to have similar properties as classical SMGs Extended Chandra Deep Field South 870μm APEX/LABOCA Survey SMMJ033229.5 (z=4.76 from optical spectrum) Weiss et al. (2009) Coppin et al. (2009)

  22. Spectroscopically confirmed z > 4 SMGs • Gas masses: ≈ 3x1010M • Stellar masses: ≈ 3x1010M • Baryonic masses: ≈ 6x1010M To date, 4 spectroscopic confirmations of z > 4 SMGs via CO observation (Schinnerer et al. 2008; Daddi et al. 2009; Coppin et al. 2010) Similar bulk properties as the ‘classical’ z ≈ 2 SMG population SMMJ033229.5: ATCA CO(2-1) detection Coppin et al. (2010)

  23. Submillimetre galaxies at z > 4 Constraining models of galaxy formation and evolution • Model prediction of the volume density of SCUBA galaxies

  24. A new population of ultra-bright high-z millimetre galaxies The South Pole Telescope (SPT 10m) Observations at 1.4, 2 and 3mm Zoom-in on 2mm map Carlstrom, Vieira, Marrone

  25. Revised Submm number counts J. Vieira

  26. A new population of ultra-bright high-z millimetre galaxies The nature of these new, extremely bright SMGs is not known, nor are their redshifts It is possible that they are strongly gravitationally lensed SMGs at z > 4 They could be the ultra high-z tail of SMGs expected (but not found until now) Vieira, Marrone

  27. A new population of ultra-bright high-z millimetre galaxies How do models account for these new, ultra-bright SMGs? ? • Model prediction of the volume density of SCUBA galaxies

  28. Probing z > 4 SMGs with ALMA

  29. Greve et al. (2004) Blain et al. (2002) Eales et al. (2003) SMGs QSOs =2: Td = 20-70K Eales et al. (2003): the 850-/1200-um flux ratio is sensitive to redshift (beyond z=3). SCUBA photometry of MAMBO sources  tentative evidence of z>>3 or peculiar dust properties =1.0: Td = 20-70K Greve et al. (2004): unbiased comparison between SCUBA and MAMBO maps. Consistent with Eales results The 850-/1200-m flux ratio

  30. SCUBA Drop-Out galaxies (SDOs) • Conclusions: • Are the SCUBA and MAMBO populations are not identical? • NO - substantial overlap, but a significant fraction (40%) of the mm-selected sources are not accounted for by the submm data. • Are SDOs z>>3 or peculiar ‘cold’ SED galaxies? • INCONCLUSIVE - due to z-Td degeneracy. But we feel the high-z scenario is more likely • Are SDOs rare and extreme systems? • HARD TO SAY – ~40% of ‘normal’ MAMBO qualify as SDOs. But the statistics are poor

  31. ‘Flux boosting’: low S/N sources gets boosted above the detection threshold when coinciding with positive noise peaks. Particular dire in the (sub)mm regime where the source counts are steep Philosophy of Bayesian deboosting: -assume prior knowledge about the pixel-brightness distribution N(Sp) in the noiseless map (i.e. assume number counts model) -the probability of measuring a flux Sm±m in the map is: -Use Bayes’ theorem to derive the probability that the true flux of the pixel is Sp: Bayesian Flux Deboosting

  32. Cross correlate ≥2.5 SCUBA and MAMBO catalogues and search for counterparts within 10” --> 28 SCUBA/MAMBO associations850µm ID fraction of ≥4 MAMBO sources: 30%1200µm ID fraction of ≥4 SCUBA sources: 63% Monte Carlos simulation of SCUBA/MAMBO ID fraction Null hypothesis: the 850µm/1200µm flux distribution for our MAMBO+SCUBA (≥2.5) sample is representative for all MAMBO and SCUBA sources

  33. Monte Carlos of the 1200µm ID fraction of SCUBA sources:Method: 1) Randomly select flux from N(S850) for ≥4 sample 2) Randomly select S850/S1200 from N(S850/S1200). Compute S1200 3) Randomly select 1200 4) Ask: is S1200/1200 ≥ 2.5 ? 5) Record ID fraction Repeat 10000 times… Monte Carlos simulation of SCUBA/MAMBO ID fraction

  34. Monte Carlos of the 850µm ID fraction of MAMBO sources:Method: 1) Randomly select flux from N(S1200) for ≥4 sample 2) Randomly select S850/S1200 from N(S850/S1200). Compute S850 3) Randomly select 850 4) Ask: is S850/850 ≥ 2.5 ? 5) Record ID fraction Repeat 10000 times… Monte Carlos simulation of SCUBA/MAMBO ID fraction

  35. Monte Carlos simulation of SCUBA/MAMBO ID fraction Suggest that ‘850m-blank’ MAMBO sources are at z>>3 or have cold/peculiar SEDs Results: > The null hypothesis applies to SCUBA sources, but not to all MAMBO sources > Evidence for a 1200m population which are not consistent with the 850/1200 flux ratio distribution for sources found jointly at 850m and 1200m > We are ‘missing’ 40% of the MAMBO sources at 850m, suggesting that almost half of the population has very low S850/S1200 values - i.e. are submm drop-outs (SDOs)

  36. Expected 1200µm ID fraction of SCUBA sources 71% 63% Monte Carlos simulation of SCUBA/MAMBO ID fraction Expected 850µm ID fraction of MAMBO sources 30% 70% P ~ 6 x 10-5

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