STUDY SUMMARY - IPMU

SUMMARY REPORT
WIDE FIELD FIBER-FED OPTICAL
MULTI-OBJECT SPECTROMETER (WFMOS)
Table of Contents
1.0 INTRODUCTION ...................................................................................................... 3
1.1 Proposal Organization.............................................................................................5
2.0 SCIENTIFIC CASE AND REQUIREMENTS............................................................. 6
2.1 Context.......................................................................................................................6
2.2 Dark Energy and Modified Gravity.........................................................................7
2.2.1 The Challenge of Cosmic Acceleration ....................................................7
2.2.2 A Dark Energy Strategy ..............................................................................7
2.2.3 Baryonic Acoustic Oscillations ...................................................................7
2.2.4 Modified Gravity and Redshift Space Distortions ...................................8
2.3 Proposed WFMOS Surveys ...................................................................................9
2.3.1 Survey Strategy: Changes Since the Feasibility Study..........................9
2.3.2 Synergy with HyperSuprimeCam ............................................................11
2.4 Galactic Archaeology.............................................................................................12
2.4.1 Near-Field Cosmology Comes of Age ....................................................12
2.4.2 Survey Strategy: Differences with the Feasibility Study ......................13
2.5 Additional Science..................................................................................................14
2.5.1 Determining the Neutrino Mass ...............................................................14
2.5.2 Studies in Galaxy Formation ....................................................................15
2.6 Conclusion...............................................................................................................15
3.0 INSTRUMENT DESCRIPTION............................................................................... 18
3.1 Rationale..................................................................................................................18
3.2 Instrument Overview..............................................................................................18
3.3 Major Requirements ..............................................................................................22
3.4 High-Level Assumptions .......................................................................................25
3.5 Instrument Trades ..................................................................................................27
3.6 Metrology Camera System ...................................................................................27
3.7 Field Element ..........................................................................................................29
3.8 Acquisition and Guide Camera ............................................................................30
3.9 Prime Focus Instrument ........................................................................................31
3.10 Positioner.................................................................................................................34
3.11 Fiber System...........................................................................................................42
3.12 Spectrograph...........................................................................................................45
3.13 Detector System.....................................................................................................50
3.14 System Software ....................................................................................................53
3.14.1 Observation Preparation ...........................................................................53
3.14.2 Observation Management ........................................................................53
3.14.3 Observation Execution ..............................................................................54
3.14.4 Engineering and Test Software ...............................................................54
3.15 Data Reduction.......................................................................................................56
ii