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Emission Lines for BAO: Ground & Space

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Emission Lines for BAO: Ground & Space

M. Lampton

UCB SSL

1 Dec 2006

Rewrites May 2007, Sept 2009, Nov 2009

- 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

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

P(k) from Cole et al 2dFGRS arXiv 0501174, Fig.15

Cosmic variance

Shot noise

M.Lampton Sept 2009

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

M.Lampton Sept 2009

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

z=0.08

z=0.24

z=0.40

M.Lampton Sept 2009

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

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

z=0.89

z=0.91

z=1.19

z=1.47

M.Lampton Sept 2009

M.Lampton Sept 2009

z=0.41

z=0.42

z=0.63

z=0.84

M.Lampton Sept 2009

Halpha [O II]

0.5<z<1.0

1.0<z<1.4

1.4<z<1.7

M.Lampton Sept 2009

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

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

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

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

M.Lampton Sept 2009

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

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

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

BigBOSS

[O II] 3727,3729

Model MDLFs

M.Lampton Sept 2009

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

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M.Lampton Sept 2009

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

JDEM, Hα 6563

Model MDLF

M.Lampton Sept 2009

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

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