From FOCAS to WFMOS??? for deep galaxy studies

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From FOCAS to WFMOS???for deep galaxy studies

• Youichi Ohyama
• ASIAA (Taiwan)

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Abstract

• I was asked by SOC to give my comments.
• This is a WFMOS business session.
• WFMOS is great. No doubt.
• Judging from all previous talks.
• WFMOS ??????(?)???????????
• Diversity?
• Noted by Sutou san.
• Then, what kind?
• Which way to go for diversity?
• Worlds ideas
• YOs idea (?)
• The talk is biased for ??????.
• ???????? WFMOS ???????????

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WFMOS era?

• Target years 2016
• 7 years from now
• FOCAS 16(?) year old.
• Already retired.
• HDS also retired?
• No optical spectrograph of our own for some
  years?
• GMOS will also retire.
• May be no direct replacement
• JWST 3 year old.
• TMT has just arrived.

File from Subarus decision for 2020 conf.
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What shall I do with WFMOS? 1

• WFMOS the Monster Spectroscopy Surveyor
• gt1500 fibers, 1.5deg fai FOV!
• How shall this monster fit my science?
• AKARI NEP survey?
• DEEP lt1 deg fai, WIDE 3 deg fai
• Too small to fit the WFMOS FOV and its survey
  size.
• AKARI all-sky survey?
• FIR (FIS) bright sources 4E4 sources/4pi
• Only a few sources in a WFMOS FOV
• Too sparse (and probably too bright) for WFMOS

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What shall I do with WFMOS? 2

• To Improve/extend existent FOCAS science
• From my works
• Z3.1 LyA blob, long slit (LS)
• Z3.6 LyA nebula around RG, LS
• Z4.7 QSO companion at LyA, LS (2 slit PA)
• Compact but slightly extended (several arcsec)
• Medium-deep spectroscopy (Texp16 h).
• Rather rare objects
• Demands
• Spatial information and good sky sub.
• Need slits

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What shall WE (FOCAS users) do with WFMOS?

• From other FOCAS science highlights (for high-z
  studies)
• Zgt6.6-6.9 LAEs
• Z-band sensitivities, good sky sub., rather rare.
• Z6.6 HIMIKO (extended LAE or high-z blob)
• spatial info., good sky sub., rather rare.
• Zgt6 GRB
• Timing (ToO), Z-band sensitivity, accurate sky
  sub.
• Z5.7 LAE Clumps
• IZ sensitivity, good sky sub.
• Z5 LBGs (absorption)
• RZ sensitivity, accurate sky sub.
• Z3.1 LABs
• FOV, spatial info.
• Zgt1 SNe for cosmology
• Timing (ToO)
• Z1.0 clusters
• FOV

Blue WFMOS will fit the project Red WFMOS might
have some troubles Green WFMOS seems OK, but
too much powerful/not optimized
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What has been MISSing so far with FOCAS science

• Big survey (due to smaller FOV)
• Analyses of stellar spectra (absorption) for
  hihg-z sources (zgt3)
• Not just LyA emission between OH lines,
• But with narrow absorptions beneath SKY.
• Second-line science for high-z emitters
• HeII from extreme LyA emitters (PopIII candidate)
• LyA blobs seen in other lines
• excitation, true velocity field
• This is partly due to 10000A wall.

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What shall we do to EXTEND FOCAS successAn
example of LAE search

• Why not go beyond the IOK-1?
• Search for LAEs beyond zgt7
• Search for very first light in the universe
• Many teams were inspired by Subarus success, and
  have been moving forward.
• Examples

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DAZLEDark Ages Redshift Z Lyman Explorer

• Dedicated NB NIR imager for VLT
• Search for Blank-field LyA emitters at z7.7
• 1056nm and 1063nm NBs, FWHM1nm

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F2T2Flamingos-2 Tandem Tunable Filter

• Fully-tunable across YJ
• Tandem etalons for better OH blocking
• Narrow FOV for targeted cluster lenses
• Option With AO
• JWST TFI prototyping

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FBG Fiber Bragg Grating

• Optical fibers to eliminate only OH lines
• OH suppression over 98
• While keeping 90 throughput at JH
• Proposed for TMT instrument RD

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FBG simulation

• The case with 30m
• But improvement with 8m is also expected
• Amazing

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FLEX First Light Explorer

• IFU with bundled FBGs
• Ultimate sensitivity for first-light sources, at
  JH, though small FOV
• Z613
• 1X1, 91 element IFU
• With AO at VLT
• But first to install existing spectrograph

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Common keywords

• Dedicated instruments
• Fully-tuned for a single purpose
• Innovative OH suppression device
• Photonics, tandem Etalon
• Prototyping new technology for even future
  instruments
• Space application, TMT
• Niche?

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Niche?driver of new technology for future!

• Niche as explained in WIKIPEDIA.jp
• ???( Niche )??????????????????????????????????????
  ??????????????????????????????????????????????????
  ?????????????????????????????????????????????????
  ??????????????????????????????6500???????????????
  ??????????(?????)?????????????????????????????????
  ?(????)???????????????????????????????????????????
  ?????????????

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Naive idea from our(?) demandsFaint
Spectrographoptimized for High-Z Studies

• Optimized for deep zYJ spectroscopy
• for 2nd line science
• stellar feature analyses
• Faint Object zYJ Spectrograph (FOCAS-zYJ)
• Last frontier(?) accessible without innovative
  device
• Concepts
• Optimized for zYJ
• 8000-13000AA
• 4000A room at redward of current limit for new
  science
• Better sensitivity and S/N at zYJ
• to achieve FOCAS- and/or DEIMOS quality
• Sky-sub conscious
• NIR chips

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A bit more on Spec.

• To maximize sensitivity at zYJ
• NIR chips (Hawaii-II?)
• to be more red sensitive than Hamamatsus CCDs
• Simple optics and thought-put oriented design
• Medium-resolution (Rgt5000) for OH software
  suppression
• Very low readout noise NIR chip (6e RMS)
• To be read-out limited even beyond 10000A
• Flexure compensation to ensure good OH
  subtraction.
• Simple fabrication
• No needs for optics cooling
• Options
• AO (GLAO) or MOS (room temp), NBs (room temp)
• Optimization for Keck
• To achieve DEIMOS FOV

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Peoples opinion

• Pushing the VLT spectroscopy of Distant Galaxies
  to the Limits and Future Prospects, Andrea
  Cimatti (2009), In Science with the VLT in the
  ELT era
• Although this is very challenging from the
  observational point of view, 8m-class telescopes
  could still play a role before the advent of JWST
  and Extremely Large Telescopes (ELTs) if equipped
  with appropriate instrumentation. For instance, a
  multi-slit spectrograph with performances and
  sensitivity optimized in the zYJ spectral region
  (possibly extended to the H-band) would provide
  competitive results.

Replace VLT -gt Subaru, ELT -gt TMT
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One last thingJ-HSC

• Just to search for zgt7 LAEs
• HSC with NIR detectors for (Y)J
• Replace Hamamatsu CCDs to NIR chips
• New dewer for J-HSC
• exchangeable to HSC (optical) dewer
• No need to dense-pack the chips
• Series of NB filters broad (Y)J
• (hopefully) use only infrastructures for HSC
• corrector optics
• NO optics cooling
• Etc
• Need spec. follow up? Use FOCAS-zYJ!
• Inspired by W-H Wang (ASIAA)

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Summary

• WFMOS --- great(?????). No doubt.
• Want to continue/extend FOCAS high-z science? ---
  WFMOS may not be the best instrument.
• Right instrument for the right science (????)
• Why not pursue more options?
• Many ground-based astronomers in the world are
  actually pursuing their ways.
• Could be niche, but could be revolutionary in
  near future.
• There might be another great (?????) instrument
  to fit our other demands.
• WFMOS for BAO and GA ( alpha)
• NEW faint spectrograph for high-z science (and
  other science)
• BUT I AM NOT SURE if FOCAS-zYJ and/or HSC-J
  are?????