Nikos Nikoloudakis and T.Shanks, R.Sharples 9 th Hellenic Astronomical Conference Athens, Greece September 20-24, 2009

 4 cloned spectrographs at Calar Alto 3.5 m prime focus  4 x 4k x 4k detectors with 15 µm (0.45) pixel  4000 MOS slits simultaneously over a 1°field  Spectral resolution 10 Å (R~600) with 1.5 slit  Wavelength bands: Å, Å, Å OBSERVING CAPABILITIES with Å galaxy redshifts/night for z up to 0.7 → 1.5 hrs exposure → ~ 5-6 million galaxy spectra in 200 nights → deg² sky area 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

 Observational Cosmology via galaxy redshift surveys at z~0.7 → LRGs (i<21) ELGs (i<22)  Evolution of halo masses and galaxies to z~0.5  Gravitational growth rate via z-space distortion to z~0.7  Measuring the scale of BAO at 0.5 < z < 3  Lyman Break Galaxy redshift survey at z~3  Rich galaxy cluster survey  Photo-z calibration for gravitational lensing  Galactic Archaeology Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

XMS - a further step XMS 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

Galaxy sky densities  i<20 all galaxies ~2500deg -2  21<i<22 all galaxies ~9000deg -2  i<21 z~0.5 em+absn galaxies ~5000deg -2  21<i<22 z~0.7 OII em galaxies ~5000deg -2  2dFGRS in 5% of the observing time at 6x bigger z and ~4mag fainter!!! 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

 i 6 in 1.5hr exposure in ~ 1.´´5 seeing  i 4 in 1.5hr exposure in ~ 1.´´5 seeing XMS Imaging Base Pan-STARRS 3π reaches i~22 (SDSS only i~20) SDSS stripe 82, PAU and ultimately LSST. 9 th Hellenic Astronomical Conference Nikos Nikoloudakis

Tests of survey feasibility Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

MOSCA Instrument  3.5-m Cassegrain focus at Calar Alto  FOV 10 x 8 arcmin 2  resolution ~ 28Å  ~ 70 slits/ mask William Herschel Deep Field on 12/08/2008 LRGs i<21 ELGs i<22  1 mask/ 2hrs 2 masks/ 1 hr  Green -250 grism  Seeing 1-1.5arcsec / transparency oftenly poor  Technical problems on 1hr masks – half spectra 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

z = 0.95 z = th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

z = 0.62 z = th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

WHDF redshift distribution ELG 66% successful z ~ 0.75 LRG 58% ( only 17 LRGs on MOSCA fields) z ~ 0.68 Galaxies were preselected by photo-z to have 0.4 < z < 0.8 Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

Test z success rate at Å Double-blind test using 267 GAMA spectra (JAP) 89% success for 0.4<z<0.8 Worse when OII and CaII H&K break outside range q=4 red q=3 blue q≤2 green 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

Cosmology with XMS Measuring the scale of BAO Measuring the gravitational growth rate Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

 Using CMB data we can determine precisely the physical length scale of BAO.  Combining apparent size + known physical sizes :  → angular diameter distance dA → Hubble parameter H(z) Better constraints in w= p/ρ Identification of systematics created by non-linearity in P(K) → standard ruler 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

→ oscillation in the power spectrum P(k) → spike in the two point spatial galaxy – galaxy correlation function ξ The BAO signature has been detected in the local universe: 1. 2dFGRS of z~0.1 galaxies ( Cole et al. 2005) 2. SDSS galaxy samples of z~0.35 LRGs ( Eisenstein et al. 2005) 9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

Measurement Galaxy clustering z-space distortions Test of Einstein’s gravity theory independently of geometrical tests using standard candles and rods Estimator of halo masses M/L galaxy groups haloes in CDM models Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

9 th Hellenic Astronomical Conference Nikos Nikoloudakis 21/09/2009

This quantity can measure survey efficiency for detecting BAO, Gravitational Growth Rate and relative quantities for clustering estimations. Feldman et al The shot noise of the power spectrum must be reduced below the irreducible component due to sampling variance. Errors on P(k) go as 1/sqrt(Veff(k)). Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

XMS Survey Effective Volume WiggleZ XMS GES XMS Total  XMS GES wins at small scales  +20x more halo members than BOSS  XMS Survey remains competitive with BOSS at BAO scales WiggleZ

 XMS offers order of magnitude improvement in MOS multiplex over previous spectrographs (400  4000)  Push the limits to fainter surveys with bigger volume  LRG+ELG tracers in same volume Multiple science cases!  XMS is competitive for BAO at scales Mpc  XMS is more competitive for z-space distortions at smaller scales.  BAO scale competitive with BOSS  Gravitational Growth Rate beats BOSS Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

Overview Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference

White, Song/&Percival 2008 Nikos Nikoloudakis 21/09/ th Hellenic Astronomical Conference