slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
Massive Spectroscopy of DES Targets PowerPoint Presentation
Download Presentation
Massive Spectroscopy of DES Targets

Loading in 2 Seconds...

play fullscreen
1 / 14

Massive Spectroscopy of DES Targets - PowerPoint PPT Presentation

  • Uploaded on

The Dark Energy Survey and The Dark Energy Spectrograph Josh Frieman DES Project Director Portsmouth, June 2011. Massive Spectroscopy of DES Targets. Would enable (see today’s talks) :

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Massive Spectroscopy of DES Targets' - jin

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

The Dark Energy Survey andThe Dark Energy SpectrographJosh FriemanDES Project DirectorPortsmouth, June 2011

massive spectroscopy of des targets

Massive Spectroscopy of DES Targets

  • Would enable (see today’s talks):
  • Clusters: cluster spec. z’s and dynamical masses from velocity dispersions: improve mass-observable calibration
  • WL+RSD: DESpecRedshift Space Distortions plus DES WL: powerful probe of DE and test of GR+DE vs Modified Gravity
  • LSS: radial BAO: H(z), and improved DA(z)
  • SNe, galaxy evolution: host-galaxy z’s and spectroscopic typing (metallicities, stellar masses) to control systematics
  • All: calibrate photo-z’svia angular cross-correlation?
  • Local dwarf galaxies?: small-scale probes of gravity

Weak Lensing and Redshift Space Distortions

Gaztanaga, Eriksen, et al

  • Constraints strongest if imaging and spectroscopy cover same sky, as DES+DESpec will
dark energy spectrograph despec

Dark Energy Spectrograph: DESpec

  • Upgrade of DES currently under study:
    • multi-object prime focus spectrograph for the Blanco 4m, interchangeable with DECam, 3.8 sq. deg. FOV
    • λ=600-1000 nm with resolution R~3300 at 1000 nm
    • Use DECam infrastructure (cage, barrel, hexapod, most optics, shutter, 20 spare CCDs,…): substantial cost saving
    • 10 low-cost spectrographs, 4000 robotically positioned fibers
    • Redshifts for ~7 million DES galaxies (in ~270 nights), ~20 million from DES+LSST (~800 nights)
  • Enhance Dark Energy science reach of DES by factor ~several, especially testing DE vs. modified gravity: Stage IV DETF
  • Enhance DE science reach of Stage IV LSST
  • Uniquely synergize with DES and LSST: power of `same sky’
the dark energy camera

The Dark Energy Camera

  • DECam mounted on Telescope Simulator at Fermilab
the dark energy camera1

The Dark Energy Camera

  • DECam mounted on Telescope Simulator at Fermilab
  • To first approximation, DESpec would interchange the imager with a fiber-positioning system that feeds multiple spectrographs

DESpec Concept Optical Design


C6 C5







See talk by Steve Kent

fiber positioner example
Fiber Positioner Example
  • FP with “Cobras”, “twirling posts” with rotating fiber. Two axes of rotation



Patrol Radius

See talk by Richard Ellis

fiber positioner example1
Fiber Positioner Example
  • Operating fiber-positioner on Subaru with ~400 fibers.
  • Spines pivot from mounts near the bases
  • Naturally handles a varying target density because the tips are small

FMOS Echidna on the Subaru

See talk by Will Saunders

rationales for blanco spectroscopy

Rationales for Blanco Spectroscopy

  • Uniform, deep imaging catalogs from DES+VHS for targeting:
  • enable powerful new science beyond what redshifts alone
  • provide (e.g., WL+RSD)
  • Maximally enhance science reach of DES: improve all the DE
  • methods+enable new methods (RSD, radial BAO)
  • Hemispheric synergy with LSST: part of a broader eventual
  • strategy for LSST follow-up: extend to ~15,000 sq deg
  • Excellent site: 0.65” seeing (0.9” Mosaic), high number of
  • useable nights (80%) yield fast (hence cheap) survey
  • Lower cost & schedule risks by reusing/capitalizing on many
  • DECam components: optics, CCDs, cage, hexapod, shutter


  • NOAO does not currently have plans for an Announcement of Opportunity for new instrument on the Blanco following DECam.
  • Future of NOAO facilities will depend on outcome of NSF Astronomy Division Portfolio Review in 2011-2012.
  • Need to further evaluate DESpec in the global context of planned & proposed spectroscopic survey facilities (e.g., BigBOSS, Sumire, 4MOST,…): DESpec should complement rather than compete with other projects where possible.
despec and bigboss

DESpec and BigBOSS

  • Both projects involve 4000-5000-fiber spectrographs on ~identical 4m telescopes, with related science goals.
  • DE reach increases with survey area, so ideally would survey both north (BB) and south (DESpec).
  • Similar survey power (area/depth per unit time) for the two concepts: BB larger FOV, DESpec higher fiber density.
  • DESpec uniquely covers entire survey areas of DES and LSST, maximizing synergistic science (WL+RSD).
  • DESpec would reuse much of the DECam infrastructure, resulting in cost savings.
path forward

Path Forward

  • DESpec a natural “upgrade” to the science capability of DES. Project could structurally follow the path blazed by DES: international collaboration with DOE+NSF support in the US, building on the successful DES collaboration, with opportunities for new partners.
  • Material above presented to Fermilab PAC last week, with very favorable response.
  • Revise and then release White Paper (1st draft exists) that lays out the science case, reference survey strategy & reference technical design motivated by science requirements.
  • Next few months: optimize target selection for keyDE probes, confirm with more detailed simulations. Continue to elaborate science case, carry out technical R&D, and build collaboration. Aim for external review in the Fall. Data release policy?