PAU camera

Cosmology with AccuratePhotometric RedshiftsPAUPhysics of the Accelerating UniversesurveyFrancisco Javier CastanderInstitut de Ciències de l’Espai, ICE (IEEC/CSIC), BarcelonaE. Gaztañaga, M. Crocce, P. Fosalba, R. Miquel, E. Fernández, E. Sánchez,J. García-Bellido, J. Carretero, A. Cabré, M. Eriksen, P. MartíPAU survey collaboration: Barcelona (IFAE, ICE(IEEC/CSIC), PIC), Madrid (UAM & CIEMAT)

Probing Cosmology• Cosmology is probed mainly measuring the expansionrate of the universe H(z), the rate growth of structure g(z)• One way: survey to measure the distribution of matterP(k,z) with galaxies as tracers

Survey requirements• The precision to which the galaxy power spectrum can bemeasured depends on:• Sample variance: how many independent samples of therelevant scale (~100 Mpc/h for BAO) one has ⇒ volume• Shot noise (Poisson): how many galaxies included in eachsample ⇒ densityFeldman,Kaiser,Peacock,ApJ 426,23(‏‎1994‎‏)‏P(k): power spectrumn: galaxy density3

Requirements for cosmology survey• sample large volumes• sample enough (many) objects• measure distances (how accurate?)

The trickPAU survey• Use photometry to obtain redshifts• Many cosmological applications need only “rough”spectroscopic precision (~10 Mpc/h)• Broad band imaging does not provide enough resolution• Need sufficient spectral resolution as to obtain good photometricredshifts => narrow band imaging• Previously: Combo-17, Alhambra, COSMOS, Subaru,…• Simulations: MICE

Visual illustration of the importance of z resolutionz-space, Δz = 0.03(1+z) +peculiar velocitiesz-space, Δz = 0.003(1+z) +peculiar velocitiesz-space, perfect z-resolution+ peculiar velocitiesReal space, perfect resolution

Requirements on Redshift Precisionspec(‏H(z(‏z‏)‏ d AphotoInverse of area of w 0 -w a error ellipsespecphoto(‏‎1+z‏)‏ Δz /(‏‎1+z‏)‏ Δz /Padmanabhan

Redshift SpaceDistortions

Lensing Magnification• Lensing efficiency kernel broad (cosmic shear need foraccurate photo-z’s?)• Good photo-z’s or redshifts allow you to perform crosscorrelationsbetween well-defined narrow redshift bins

Lensing Magnification• Lensing magnifies measured fluxes and alters the areaobserved and therefore changes the number of observedobjects in a magnitude limited survey• Coss-correlations between redshift bins i,j• Ratios of cross-correlations are approximately independent ofpower spectrum

PAU survey• The main goal of the PAU survey is to study cosmology/darkenergy characterising the geometry and growth of structure of theuniverse• Large volumes and moderately accurate redshifts are needed forthis purpose• The idea is to use a large field of view camera and narrow bandfilters to achieve both• The survey will use ~40 narrow band filters (~100 A wide)covering from 4500 to 8500 A supplemented by wide band filtersto image the sky and measure the position and distance (usingphotometric redshift techniques) to millions of galaxies

PAU survey• The PAU survey collaboration is in the process of building anew large field-of-view camera to be installed in the current primefocus of the WHT reaching an etendue of ~7 to carry a large areasurvey

The PAU CameraO. Ballester(2), L. Cardiel-Sas(2), J. Carretero(1), R. Casas(1), F. J. Castander(1), J. Castilla(3), M. Crocce(1), J.de Vicente(3), M. Delfino(4), E. Fernández(2), P. Fosalba(1), J. García-Bellido(5), E. Gaztañaga(1), F. Grañera(2),J. Jiménez(1), F. Madrid(1), M. Maiorino(2), P. Martí(2),R. Miquel(2), Ch. Neissner(4), R. Ponce(3), E. Sánchez(3), S. Serrano(1), I. Sevilla(3),N. Tonello(4), I. Troyano(2)(1)ICE (IEEC-CSIC), (2)IFAE, (3)CIEMAT, (4)PIC, (5)UAM14

The PAU CameraPAUCam15

The PAU CameraTelescopio William HerschelLocated ORM, La Palma, Spain• Highly oversubscribedHigh scientific output so far•Diameter: 4.2 mPrime focus: 11.73 m•Focal ratio: f/2.8Used by UK, Netherlands & SpainL. Cardiel-Sas16

The PAU CameraTelescopio William Herschel•Located ORM, La Palma, SpainHighly oversubscribedHigh scientific output so farDiameter: 4.2 m•Prime focus: 11.73 m•Focal ratio: f/2.8Used by UK, Netherlands & SpainL. Cardiel-Sas17

The PAU CameraTelescopio William Herschel•Scale: 17.58 arcsec/mmL. Cardiel-Sas18

The PAU CameraTelescopio William HerschelCurrent prime focus corrector•Field of view: 40 arcmin unvignetted60 arcmin vignettedL. Cardiel-Sas19

The PAU CameraCamara efficiency•Fill the available field of view as densely populated as possiblewith CCD detectors•Use CCD with the highest QE available in the whole wavelengthrange accessible•Size: 2048 x 4096 pixelsPixel size: 15 µm•Scale: 0.26 arcsec/pix20

The PAU CameraDetectors• Hamamatsu21

The PAU CameraDistribution22

The PAU CameraDistribution23

The PAU CameraFilters40 narrow band filters•FWHM = 10.0 nm•Spectral Range λ=450 to 850 nmRectangular transmission profile24

The PAU CameraFilters6 standard broad band filters•SDSS + Y set25

The PAU CameraFilter TraysNeed to be very close to the detectors to avoid vignetting•More filters than detectors => movable trays•Movement requirements in vacuum are technologically challenging26

The PAU CameraFilter trays27

The PAU CameraElectronicsMonsoon arquitecture (NOAO) 3 clock and bias board •7 acquisi9on boards 3 master boards •18 pre-­‐amp & rou9ng boards 28

The PAU CameraControl SystemSlow Control"Telescope"Control"System"TCS Instrument"Control"System"Alarms"Guider"Observa3on Control System Image View and Quality Analysis GUI Focal"Plane"Data Acquisi3on System 5-day"Storage"Transfer"to PAUdm Science Data Flow 29

The PAU Camera30

Main characteristicsPAU camera• Large field of view• Narrow band filters + broad band filters• good spectral sensitivity• segmented filter trays

PAU survey• The PAU survey collaboration is in the process of building anew large field-of-view camera to be installed in the current primefocus of the WHT reaching an etendue of ~7 to carry a large areasurvey• The survey will obtain photometric redshift accuracy of dz/(1+z)

PAU survey: photo-z performance

PAU survey• The PAU collaboration is in the process of building a new largefield-of-view camera to be installed in the current prime focus ofthe WHT reaching an etendue of ~7 to carry a large area survey• The survey will obtain photometric redshift accuracy of dz/(1+z)

FOM 1/σ(w0) σ(wa) 1/σ(γ) 1/σ(w0) σ(wa)σ(γ)DES (MAG) 47 (109) 35 (48) 1.6 (5) x 10 3 DESpec (MAG) 116 (401) 77 (84) 9 (34) x 10 3 DESpec (MAG+RSD) 1430 (1736) 127 (141) 182 (245) x 10 3 PAU200 (MAG+RSD) 171 (195) 31 (33) 5 (6) x 10 3 Om - ODE - h - sig8 - Ob - w0 - wa - gamma - ns - b1- db1dz- b2- db2dz+Planck+ Stage-SN II (assume bias is known)FoM 5 8 25 17 200 DESpec/DES:Factor of 4 in Growth & 30 in DEfactor of 10 in joinned FoM

• Galaxy evolutionPAU SurveyAlthough the survey is designed and optimized for DE,many other science topics could be addressed• Galactic astronomy• High redshift galaxies• Interstellar dust• Quasars and Lyα systems• Clusters• Stellar populations• Halo stars• Local group galaxies• Serendipitous discoveries• Weak gravitational lensing• Strong gravitational lensing

PAU survey• some cosmological probes do not require accurate spectroscopicredshift• exploit this with a narrow band survey delivering good photo-z’s• building a new camera for the WHT• probes: BAO (area), z-space distortions, magnification bias• sampling the galaxy power spectrum will not be limited by shotnoiseand could be traced with several tracers

DES landscape• If and when LSST operates, DECam will be out-dated• DESpec role• If DESpec is delayed or cannot happen, using narrow band filtersmay be an option for DECam