HET is the world’s third largest telescope. It will be upgraded with a uniquely powerful new instrument called VIRUS HET Mt. Fowlkes west Texas Hobby-Eberly Telescope

4 HETDEX is: →blind spectrographic survey on 9.2m Hobby-Eberly Telescope →420 square degrees in 1200 hours (140 nights) over 3 years →about 0.8 million redshifts from 1.9<z<3.8 (Ly-alpha emitters) →about 1 million redshifts from 0<z<0.5 (OII emitters) →upgraded HET with new top-end, including 22’ field →new instrument VIRUS which is 150 spectrographs (R=800 from 350nm – 580nm) →one unit spectrograph has been in use for over 2 years TIMELINE:

The Spectrograph -- VIRUS  Blind survey with 150 integral field spectrographs, known as VIRUS  Replicated integral field spectrographs (VIRUS)  Inexpensive fiber-fed unit IFS copied 150 times; deployed as 75 pairs  Each pair fed by 50x50 arcsec 2 IFU with 448 fibers of 1.5” diameter  33,600 spectra per exposure  The field-of-view is 22 arcmin  Three exposures fill area of IFU  nm coverage, R~700  Line flux limit 3.5e-17 and m AB ~22

VIRUS field layout  Grid layout of 96 IFUs each 50”x50”  feeds for other instruments at the middle of the field  Allows parallel observations with VIRUS  Baseline 75 IFUs will leave some gaps, but goal is to fill the matrix LRS feed VIRUS IFUs 100” 15.6’ Guide probes range in outer 3 arcmin radial annulus

IFU 448 fibers 50 x 50 sq. arcsec 1.5” fiber dia Observing footprint of VIRUS Net fill factor in survey is 1/7 (60 sq. deg in 420) 19.5’ Pointing centers randomized to avoid bright stars

VIRUS-P, the first unit spectrograph 8 VIRUS Prototype Funded by the George & Cynthia Mitchell Foundation, NESSI, McDonald Observatory, MPE, and AIP  1.9’x1.9’ FOV on McDonald 2.7m  4.2” diameter fibers  nm  R=900

The VIRUS-P Pilot Survey → 115 arcmin 2 surveyed on COSMOS, GOODS- S and MUNICS-S2 fields → Fields selected to have deep multi- wavelength broad-band imaging → 2.7m HST → 6 position dither pattern ensures good field coverage (3x20minutes at each position) → 5σ flux limit of ~6x erg/s/cm 2 for a point- source emitting and unresolved line 9

10 FLAT ARC LAMP SCIENCE VIRUS-P Data

Combined Frame 11 →Final combined exposure →Collapse to 1D spectrum →Ready to search for lines in 1D or 2D

12 DATA REDUCTION for VIRUS-P Data Reduction Pipeline: want to get reliable 5-sigma sources need superb sky subtraction 2 independent pipelines developed: →VACCINE out of Texas →CURE out of MPE/USM A series of paper has come out: Adams et al., arXiv Blanc et al., arXiv Finkelstein et al., arXiv Main Results: 397 emission-line galaxies detected over 169 arcmin 2 with a A range Sensitivity: 4-20 x erg/s/cm 2, Ly-alpha luminosities: 3-6 x erg/s.

VENGA

VIRUS-P  VIRUS Prototype IFU  1.7’x1.7’ FOV at HJST 2.7m  1/3 filling factor  Largest FOV of any existent IFU  4.3’’ diameter fibers on sky  Å default wavelength range  Å adjusting wavelength range  R=1000 with HETDEX Grating  R=3000 with new “Dynamics” grating

THE VENGA SURVEY VENGA 32 Sa-Sd (possible extension to E,S0) VIRUS-P+2.7m HJST FOV=1.7’x1.7’ (largest in the world) Central parts and disks out to 0.7 D – 6800 Å σ inst = 50 km s ” resolution

THE SAMPLE  Emphasis on available multi-λ data:  93% - HST Optical Imaging  77% - Spitzer IRAC(3.6, 4.5, 5.8, 8.0 μ) MIPS(24,70,160μ)  60% - Spitzer IRS spectroscopy (central part)  97% - GALEX near-UV and far-UV  63% - CO Mapping (BIMA-STINGS)  37% - HI 21cm from THINGS

CURRENT IFU SURVEYS OF NEARBY SPIRAL GALAXIES SAURON  18 Sb-Sd (total ~70)  SAURON+4.2m WHT  FOV=0.42 arcmin 2  Central Parts  4800 – 5380 Å   R=3 Å  1” resolution  Ganda et al PINGS 17 Spirals (ongoing) PMASS+3.5m Telescope FOV=1.21 arcmin 2 Whole Galaxies (tiling) Å σ inst = 250 km s -1 R=850(Red)and R=1650(blue) 2.7” resolution Rosales-Ortega et al (submitted) Califa 600 Spirals (planned) PMASS/PPAK+3.5m Telescope FOV=>1 arcmin 2 Central Parts Å σ inst = 250 km s -1 R=850(Red)and R=1650(blue) 2.7” resolution

VENGA vs. OTHER SURVEYS  4 major advantages:  Higher spectral resolution  1/2 that of SAURON and 1/10 that of PINGS.  Much better λ coverage than SAURON  Higher S/N, specially on outer parts  Big fibers are good for LSB sources.  Coarse spatial resolution is compensated by less binning.  Largest FOV in the world  VIRUS-P is the optimal instrument to conduct this survey.

Properties of Galaxies:  IFU observations of nearby galaxies can provide 2D maps of:  Gas Kinematics  Stellar Kinematics  Stellar Populations (star formation rate history)  Metallicity  Emission line fluxes and ratios  E(B-V) (both nebular and continuum)  Ages  The history of the stars and the ISM in galaxies is encoded in these quantities and the correlations between them.

THE VENGA SAMPLE Spectra of 53,874 regions across the disks of 32 nearby spiral galaxies. RED LOW-RES: COMPLETE STARTED NOT STARTED

DATA REDUCTION AND ANALYSIS  VACCINE:  Full data reduction pipeline.  Well documented.  Reduces 1 observing run in a few hours.  FLUX CALIBRATION:  VIRUS-P Extinctions Pipeline is READY!!  Absolute spectro-photometry to a 10%  ANALYSIS:  Parada

VENGA SPECTRA BLUE SPECTRUM RED SPECTRUM [SII] HβHβMg b[OIII] Hα+[NII] Ca H+K HηHη HζHζ HδHδHγHγ [OII] Blanc et al., 2009; Yoachim et al., 2010

VIRUS for 2.4m telescope  Baseline instrument:  2 VIRUS IFUs, total 448 fibers  Fiber size: 4-6 arcsec  Total FOV: ~ 2 arcmin x 4 arcmin  Wavelength: nm  Need a focal reducer and other adaptations  A rough cost estimation:  0.5M US$ for the instrument (~350RMB)  0.5M US$ for SHAO joining HETDEX 23

6/3/20166/3/20166/3/2016 VIRUS for the 2.4m  One two-channel VIRUS Unit optimized for SHAO application will use 170 micron fibers on sky  4.0 arcsec diameter at f/3.65 on 2.4 m  The IFU will be about 1.7 by 3.4 arcmin  Each channel will take light from half the IFU  Maximum resolving power can be up to R~3000 by sandwiching gratings between prisms  Maximum depends on prism material and angle  VIRUS units are designed for easy manual swapping of the disperser module to allow reconfiguration  Possible grisms are shown in the table Channel 1Channel arcmin 1.7 arcmin

What Sciences We Can Do:  Nearby galaxies: Ellipticals, Spirals, dwarfs, LSBGs, Interacting…  Globular Clusters, local group dwarfs.  Galaxy Clusters  Others: supernova remnants 25 Emission Line Strength Absorption Line Strength Stellar kinematics Gas kinematics

Advantages of VIRUS IFU for 2.4m  Fast Scientific Output  Instrumentation production is in line  Compatible to the 2.4m telescope (the 2.7m has f/8.8)  Mature software supports  Aim to commission at  Can negotiate to join VENGA (>100 nights observed)  Largest field of view and high spectral resolution  Best use of a 2.4 meter telescope  Price Low  Have good compatibility with other future VIRUS type instruments – can have large collaborations world-wide. 26

Efforts Taken So Far  The goal is to have the whole Chinese Astronomical Community benefit from the IFU.  Mini-workshop in Shanghai at Jun, 9 th, 2010  Attendees from many various institutes  Clear that Chinese Astronomical Community needs an IFU  Discussed various sciences – science book to be compiled  Drafted a MOU with Yunan Observatory  Technical working group defined  Propose a second workshop with larger group of people Early Next Spring  Open to future collaborations and contributions 27

Summary  VIRUS is a good opportunity for China to get its own IFU science.  Timeline fast  Great science capability  Mature, tested workable  To be discussed: how can VIRUS help on our own IFU technical developments 28

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