Michael Levi (Lawrence Berkeley National Laboratory), M. Lampton (UCBerkeley Space Sciences Lab), and M. Sholl (UCBerkeley Space Sciences Lab)

WFIRST: Top Recommendation of Astro 2010

• Dark energy investigations using Weak Lensing, BAO, and Supernovae

• Exoplanet microlensing survey in the Galactic Bulge

• Wide field guest investigation surveys in the near infrared

Wide Field Infrared Survey Telescope Science Yield

We gratefully acknowledge the support by the Director, Office of Science, U.S. Department of Energy, through contract DE-AC03-76SF00098. Artwork by R.E.Lafever. Night sky image courtesy of NOAO.

Weak Lensing Simulation:

> Galaxy sizes & fluxes from zCOSMOS: Leauthaud et al 2008; Jouvel et al 2009

> Survey rate is set by FoV and exposure time reaching 25th magnitude

• BAO Simulation:

> Emission line galaxy fluxes, sizes, and redshifts from Ilbert et al 2005

> Survey rate chosen to deliver 66% detection at F=2.0e-16 erg/cm2.s

• Supernova Simulation:

> Assumes discoveries are given; WFIRST does only the follow-up spectroscopy

> Eight spectra distributed over light curve + one deep spectrum near peak

• Exoplanet Microlensing FoM Scaling:

• > Not a simulation; instead scaled from MPF mission projection (ref 6)

• > Scaling factor = FoV * Aeff * ObsEffic * Δλ * λ /√NeffPixels

• > ObsEffic allows 256 days/year articulated, or 128 days/year fixed panels

• > We anticipate that the WFIRST Science Definition Team will do simulations

New Developments Since Astro 2010 Report• Unobscured aperture shown highly effective at boosting S/N ratio

> Allows higher survey rate for the same aperture: more survey science per year

> Lampton et al., Proc SPIE 7731 (2010)

• Focal optical train allows separate focal lengths for imaging and spectroscopy

> Permits high resolution WL survey & EPML with high signal to noise ratio

> Simultaneously delivers wide field slitless spectroscopy with coarser pixel scale

> Sholl et al., Proc SPIE 7731 (2010) and Sholl et al., this AAS conference (2011).

• Large focal plane (8x4 MCTs) designed, built, and undergoing space qualification

> Higher pixel count and higher survey rate for the high resolution imager

> Jelinsky et al., this AAS conference (2011)

ResultsWeak Lensing > High survey rate > High galaxy density

Exoplanets > Unobscured aperture helps reduce confusion

BAO > 2E-16 erg/cm2.s at 66% effic > High survey rate > Can co-observe with WL

Supernovae > Can reach redshift z~1.4 > Superior SN yield > Wide λ range and z range help to control systematic errors

Four alternative WFIRST Payloads:• Telescope aperture 1.3 or 1.5m unobscured

• Pixel scales: imager= 0.18 arcsec; spectrom=0.36 or 0.44 arcsec

• Field of view: imager = spectrometer = 0.26 or 0.33 sq degrees simultaneously

• Articulated solar panels & 45º front baffle angle for nearly 270 days/year on Bulge

• Fully articulated K-band antenna for continuous downlink: 3 ground stations

• Orbit: Earth-Sun L2 halo orbit similar to JWST

Mission   WFIRST A WFIRST B WFIRST C WFIRST D JDEM Probe A Probe B                      Euclid GEST MPF      dichroic no dichroic dichroic no dichroic Omega  no dichroic dichroic VIS NIR Si CCD MCT      ref 1 ref 1 ref 1 ref 1 ref 2 ref 3 ref 3                        ref 4 ref 5 ref 6  

Telescope Telescope Aperture= 1.5m unobs 1.3m unobs 1.5m unobs 1.3m unobs 1.5m obs 1.1m unobs 1.1m unobs 1.2mobs 1.2m obs 1.1m obs meters aperture                  

Imager Wavelength Range= 0.5 to 1.5 0.5 to 2.0 0.5 to 1.5 0.5 to 2.0 0.4 to 2.0 0.4 to 2.0 0.4 to 1.5 0.55 to 0.92 0.9 to 2.0 0.6 to 1.0 0.6 to 1.7 microns Filter Bands= broad broad broad broad V, R, I, J, H V, R, I, J, H V, R, I, J R+I+Z Y, J, H R broad   Pixel Scale= 0.18 0.18 0.18 0.18 0.18 0.45 0.175 0.10 0.3 0.21 0.24 arcsec Number of SCAs= 32 32 25 25 24 8 18 30 12 32 35 SCAs Imager FoV= 0.336 0.336 0.262 0.262 0.252 0.524 0.178 0.461 0.487 2.055 0.652 square degrees

RESULTS: WL WL Survey Rate(25th mag)= 5554 4087 4614 3050 2134 -- 5018 2102 -- -- -- sqdeg/year relative to JDEM-Omega 2.6 1.9 2.2 1.4 1.0 2.4 1.0 relative to JDEM-Ω Single Waveband gal/sqarcmin 42 42 42 39 32 39 29       gal/sqarcmin

RESULTS: EP Exoplanet Discovery Rate FoM= 1.43 1.46 1.12 1.14 0.21 0.55 0.29 0.06 0.23 1.26 1.00 relative to MPF WFIRST w/ fixed solar panels= 0.72 0.73 0.56 0.57               Data Rate= 65.10 63.59 50.86 49.68 31.72 11.30 24.55 6.28 8.46 30.72 26.39 Mb/sec: 2:1 + 30%

Slitless Spectro Method= 1 prism 2 prisms 1 prism 1 prism 2 prisms 1 prism 1 prism none 4 grisms none none   Wavelength Range= 1.5 to 2.0 1.1 to 2.0 1.5 to 2.0 1.1 to 2.0 1.1 to 2.0 1.5 to 2.0 1.5 to 2.0   1.1 to 2.0     microns Halpha redshift range= 1.3 to 2.0 0.7 to 2.0 1.3 to 2.0 0.7 to 2.0 0.7 to 2.0 1.3 to 2.0 1.3 to 2.0   0.7 to 2.0       Pixel scale= 0.36 0.36 0.45 0.45 0.37 0.45 0.30   0.34     arcsec Number of focal planes= 1 2 1 1 2 1 1   1     FPs SCAs per focal plane= 8 4 4 4 6 8 18   12     SCAs Spectrometer FoV= 0.336 0.336 0.262 0.262 0.532 0.524 0.524   0.487     sq deg

RESULTS: BAO BAO Survey Rate, 66% @2E-16 erg= 11216 4019 8468 3001 3782 9378 10097 1498     sqdeg/year relative to JDEM-Omega 2.97 1.06 2.24 0.79 1.00 2.48 2.67 -- 0.40     relative to JDEM-Omega

SN Spectrom Method= IFU IFU IFU IFU Slitless Slit Slit none none none none   Wavelength Range= 0.4 to 2.0 0.4 to 2.0 0.4 to 2.0 0.4 to 2.0   0.5 to 2.0 0.5 to 2.0           Slit scale= 0.36 0.39 0.35 0.40   0.51 0.51         arc seconds

RESULTS: SNe Max Redshift, 50% @S/N>8= 1.4 1.4 1.4 1.4   1.4 1.4            SNe per year= 2306 1630 2315 1624   955 977            1: Sholl,M.J., et al.,217th AAS conf (2010);          2:Gehrels,N., arXiv 1008.4936 (2010);          3: Content,D.A. et al., Proc SPIE 7731 (2010)          4: Duvet,L., "Euclid Reference Payload Document RD-s" ESA (2010);         5: Bennett,D.P. et al., GEST; Proc SPIE 4854 (2003);        6: Bennett,D.P., MPF; arXiv 0902.3000 (2009).