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Emission Lines for BAO: Ground & Space

Emission Lines for BAO: Ground & Space. M. Lampton UCB SSL 1 Dec 2006 Rewrites May 2007, Sept 2009, Nov 2009. Intro. Much previous BAO work has used LRGs: very bright! But few in number Emission line galaxies are more numerous but not so bright

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Emission Lines for BAO: Ground & Space

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  1. Emission Lines for BAO: Ground & Space M. Lampton UCB SSL 1 Dec 2006 Rewrites May 2007, Sept 2009, Nov 2009

  2. Intro • Much previous BAO work has used LRGs: very bright! But few in number • Emission line galaxies are more numerous but not so bright • Star Formation Rate is gauged by emission lines esp Hα and [O II] • [O II] 3727 can accomplish a lot from mountaintops: 1 micron is z=1.68 • Hα 6563 although stronger, requires spaceborne observatory • Then there’s [O III] 5007, yet another tool. M.Lampton Sept 2009

  3. Plan 1. BAO Goals: nP ~ 1 and lots of modes 2. Review SFR(z) and model it 3. Review LF(z) for Halpha and [O II] 4. Model LF(z) for Halpha and [O II] 5. Predict harvests of BAO surveys, space and ground. Rough analogy to Parkinson et al “Optimizing BAO Surveys” arXiv 0702040 which was done to optimize WFMOS (ground only): they found it best to concentrate on 0.8<z<1.4 over the widest possible sky area and to kiss off Lyα at z~3. Throughout: I adopt a “737” cosmology. M.Lampton Sept 2009

  4. Step 1: Uncertainties in the Acoustic Scale Lengthe.g. Blake et al 0510239 (2005); see also Reid et al 0907.1659 P(k) from Cole et al 2dFGRS arXiv 0501174, Fig.15 Cosmic variance Shot noise M.Lampton Sept 2009

  5. Step 2: SFR, Hα, [O II] are strongly correlated Local, SDSS: Sumiyoshi et al arXiv:0902.2064 (2009) Fig 3 Local; Kennicutt, Ap.J. 388, 310 (1992) Sum of 3727, 3729 Hα 6563 singlet M.Lampton Sept 2009

  6. Step 2: ELGs are widely used for SFR estimationLy et al., ApJ 657 738 (2007) M.Lampton Sept 2009

  7. Step 2: Review and model SFR(z) The Compilation: Hopkins & Beacom ApJ 651, 142 (2006) Fig.1 The parabola: log(SFR)=-2.00+5*(x – x2) where x=log(z+1) See also Gonzales et al arXiv 0909.3517 M.Lampton Sept 2009

  8. Step 3: LF data, Hα, continuedfaint end: Subaru; Ly et al., Subaru, ApJ 657 738 (2007), Fig 10 z=0.08 z=0.24 z=0.40 M.Lampton Sept 2009

  9. HiZELS: a high redshift survey of Hα emitters. I: the cosmic star-formation rate and clustering at z = 2.23 J. E. Geach et al; UKIRT HiZELS: NIR narrowband at 2.12um, COSMOS field 0.6 sqdeg arXiv:0805.2861v1 M.Lampton Sept 2009

  10. MULTI-WAVELENGTH CONSTRAINTS ON THE COSMIC STAR FORMATION HISTORY FROM SPECTROSCOPY: THE REST-FRAME UV, H, AND INFRARED LUMINOSITY FUNCTIONS AT REDSHIFTS 1.9<z < 3.41 Reddy et al arXiv:0706.4091: 2000 SpectroZ, 15000 PhotoZ; Steidel Keck I w/ LRIS (2004) M.Lampton Sept 2009

  11. Step 3: LF data [O II]Ly et al., Subaru w/ narrowband filters; ApJ 657 738 (2007) Fig 12 z=0.89 z=0.91 z=1.19 z=1.47 M.Lampton Sept 2009

  12. Step 3: LF data, [O II], continuedZhu et al., arXiv 0811.3035: DEEP2 (Keck II + DEIMOS), 14000 galaxies M.Lampton Sept 2009

  13. Step 3, continued: how about [O III] 5007?Ly et al., Subaru Deep Field; ApJ 657 738 (2007) Fig. 11 z=0.41 z=0.42 z=0.63 z=0.84 M.Lampton Sept 2009

  14. Step 3 concluding:LF compilationSumiyoshi et al: Compilation based on data from SDF; arXiv 0902.2064 Halpha [O II] 0.5<z<1.0 1.0<z<1.4 1.4<z<1.7 M.Lampton Sept 2009

  15. Step 4: Model the LF(z) for each line Simplest Abell Luminosity Function • Abell model (ARAA v.3, 1-22, 1965) parameters Lb, Nb at the break; • Nearly flat power law at faint end • Break • Nearly inverse-square power law at bright end • Schechter model (ApJ 203, 297-306, 1976) parameters L*, Φ* at the break; • Nearly flat power law at faint end • Break • Exponential decrease at bright end • Both developed for galaxy continuua • They differ only at the bright end: Abell=slope; Schechter=dropoff. • Which might apply for line emission? • Because of the log-log straight-line LFs seen in DEEP2 (which go to very sparse densities) I adopt the Abell model here. • Other adopters: Hao et al 0501042 (ELGs); Croom et al MNRAS 349 1397 2004 (QSOs) M.Lampton Sept 2009

  16. Step 4: Hα LF model log(Nb) = -3.5+2.0*(x-x²) log(Lb) = +41.5+3.0*(x-x²) where x = log10(1+z) Sumiyoshi et al (2009) 0.5<z<1.0 1.0<z<1.4 1.4<z<1.7 M.Lampton Sept 2009

  17. Sumiyoshi et al (2009) Step 4: [O II] LF model log(Nb) = -3.5+2.0*(x-x²) log(Lb) = +41.1+3.0*(x-x²) where x = log10(1+z) 0.5<z<1.0 1.0<z<1.4 1.4<z<1.7 M.Lampton Sept 2009

  18. Step 4: [O II] model log(Nb) = -3.5+2.0*(x-x²) log(Lb) = +41.1+3.0*(x-x²) DEEP2; Zhu et al., arXiv 0811.3035 M.Lampton Sept 2009

  19. Step 5: Survey Yieldassumes “737” universe M.Lampton Sept 2009

  20. Abell distribution eyeball fitted to Sumiyoshi et al 2009 Hα NEWS FLASH : Previously sought nP=1 and Zmax=2; but Linder and others (this conference) recommend NP=2 or even 3; Zmax=1.7 not 2.0 For a given nP, what Hα flux do we expect? This extrapolated LF based on Sumiyoshi has many uncertainties, and the JDEM BAO team has recommended a higher sensitivity, ~ 1.6E-16 erg/cm2s M.Lampton Sept 2009

  21. For a given nP, what [O II] flux do we expect? Abell distribution eyeball fitted to Sumiyoshi et al 2009 [O II] 3727+3729 BigBOSS White Paper Fig.2 based on DEEP2 and VVDS Goal: doublet flux ~ 1E-16 erg from this alone. But atmospheric observing complications and uncertainties about the LF at z>1.5 argue for higher sensitivity; working goal = 2.5E-17 erg/cm2sec for each component. M.Lampton Sept 2009

  22. BigBOSS [O II] 3727,3729 Model MDLFs M.Lampton Sept 2009

  23. Atmospheric Transmission at Gemini Northpresumably similar at KPNO?http://www.gemini.edu/sciops/ObsProcess/obsConstraints/ocTransSpectra.html U B V R I Z Y J H K 5.0mm H2O M.Lampton Sept 2009

  24. Atmospheric Emissionhttp://www.gemini.edu/node/10781?q=node/10787#OpticalSkySpectrum M.Lampton Sept 2009

  25. MDLF Results for BigBOSSGoal is to use < 1 hour exposures and get SNR=8 (see chart 22)…at z=2: 2.5E-17 erg/cm2s, will need the whole 4ksecat z=1: 1E-16 erg/cm2s, will need < 1 ksec At Tobs = 1 h, 4000 fibers and 100 nights/year at 8h/night is 3 million targets per year -- and of course there is additional yield since most targets have z<2.0 and so won’t need the full 4000 seconds of exposure each,so smart fiber reallocation can improve yield rather than SNR. M.Lampton Sept 2009

  26. JDEM, Hα 6563 Model MDLF M.Lampton Sept 2009

  27. MDLF Results for JDEMGoal is to use ~ 1ksec exposures Hα and get SNR>6…at z=2: can get to 2.5E-16 erg/cm2s, using 1ksecat z=1: with 1ksec will gain improved SNR At 1 kilosec exposures, 6 MCT sensors & 0.5 arcsec pixels, the FOV is 0.46 sq degrees. With 100 sec lost per maneuver and 70% on orbit efficiency, the net survey rate is 9000 square degrees per year. M.Lampton Sept 2009

  28. Recent Relevant Results! Conclusions • JDEM-BAO: entirely feasible! • BigBOSS: entirely feasible! • Geach et al “Empirical Halpha emitter count predictions for dark energy surveys” arXiv 0911.0686: ELGs, Ha, 0.5<z<2. • Parkinson et al “Optimizing BAO surveys II: curvature, redshifts, and external datasets” arXiv 0905.3410 • Hutsi, “Power spectrum of the maxBCG sample: detection of AO using galaxy clusters” arXiv 0910.0492 • Stril et al, “Testing Standard Cosmology with Large Scale Structure” arXiv0910.1833; specifically compares BigBOSS vs JDEM-PS. M.Lampton Sept 2009

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