An Introduction of VIRUS-P & VENGA

1. An Introduction of VIRUS-P & VENGA 2009, ApJ, 704, 842 2010, ApJL, 716, 4 2010, ASPC, 432, 180 2011, ApJ, 729, 129 https://luna.mpe.mpg.de/wikivenga/index.php/Main_Page Jun YIN 2011.05.11

2. Content • VIRUS-P Instrument • VENGA Survey Basic Information & Survey Design • Examples: • Spatially resolved SF law – M51a (2009, ApJ, 704, 842) • Stellar disk truncation – NGC 6155 (2010, ApJL, 716, 4) • Summary

3. VIRUS-P Instrument

4. VIRUS-P Instrument VIRUS-P Visible Integral-field Replicable Unit Spectrograph-Prototype IFU • 1.7’x1.7’ FOV at HJST 2.7m Largest FOV of any existent IFU • 1/3 filling factor  3 dithers • 4.3’’ diameter fibers on sky • 246 fibers  738 spatial resolution elements • 4600-6800Å red setup • 3600-4400Å blue setup • R=1000 with HETDEX Grating • R=3000 with new “Dynamics” grating

7. Data collection • Bias frames and twilight frames • Taken at the start and end of the night • For both flat fielding and determining the position and shape of each fiber profile • Mercury (汞) and cadmium (镉) arc lamp frames • Cadmium 3611.3 Åline and mercury 5769.6 Å line • For wavelength solution and determination of instrumental resolution • The spectro-photometric standard star was observed • For flux calibration & PSF determination • Guider frames (4’.5×4’.5 offset, 512×512 pixel) • Saved every 30s • For changes in atmospheric transparency, IFU astrometry • A cadence of 20 minute science exposures bracketed by 5 minute sky nods

8. Data reduction process (Vaccine) • The overscan and bias are subtracted from all frames, bad pixel masked; • Standard stars  PSF • Twilight flats  determine each fiber trace; • Arc lamp frames  wavelength calibration (twice); • Twilight flats  remove sky spectrum, create a flat-field frame; • Flattened arc lamp frames  determine the wavelength solution again; • Flatten  divide all science, sky, and spectro-photometric standard frames by both the fiber profile and the pixel-to-pixel flats. • Sky subtraction • Cosmic rays are located and masked • Fibers containing either foreground or background objects are located and masked.

9. VENGA Survey

10. Motivation • Consensus on LCDM model • Galaxies form in the bottom of potential wells in the dark matter distribution. • Gas accretion and mergers trigger star-formation. • Galaxies form, and evolve building up their stellar mass during Gyrs. • We do not fully understand the baryonic physics that drive galaxy formation and evolution • What sets the SFR inside galaxies? • How do accretion and feedback interplay in shaping the ISM? • How, and in what grade do mergers and secular processes shape present day galaxies? • ……

11. Need for spatially resolved • IFU observations of nearby galaxies can provide 2D maps of: • Gas kinematics • Stellar kinematics • SFR & stellar populations (star formation rate history) • Chemical abundances • ISM density & ionization states • Emission line fluxes and ratios • E(B-V) (both nebular and continuum) • Line indexes • The history of the stars and the ISM in galaxies is encoded in these quantities and the correlations between them.

12. The VENGA survey • VENGA The VIRUS-P Exploration of Nearby Galaxies • An extragalactic IFU survey, disks of 32 nearby normal spiral galaxies. • The sample spans a wide range in Hubble types, SFR, and morphologies. Galaxies showing classical and pseudobulges, as well as barred and unbarred objects are present in the sample.

13. 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 D25 • 3650 – 4400 Å/4600 – 6800 Å • σinst = 50 km s-1/120 km s-1 • 4.3” resolution

14. The VENGA survey

15. Last updated 27/03/2011 Completion status 32% red completed red started blue completed blue started The VENGA Sample of 32 nearby spirals ordered by RC3 morphological type from early (top left) to late (bottom left) types. White boxes mark the 1.7'x1.7' field of view of the VIRUS-P spectrograph.

16. The VENGA Sample

17. The VENGA Sample Availability of multi-wavelength imaging • 93% - HST Optical Imaging • 77% - Spitzer IRAC(3.6, 4.5, 5.8, 8.0μ) 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

19. The VENGA survey design • 1, 2 or 3 pointings (3 dithers) on each galaxy: • Ensure coverage beyond 0.7 D25 requires 77 pointings in total. • 2 instrumental setups for each pointing: • Blue – High Resolution Setup: • 3650 – 4400 Å • σinst = 50 km s-1 (Galaxy Dynamics Grating) • Red – Low Resolution Setup: • 4550 – 6800 Å • σinst = 120 km s-1 (HETDEX Grating) • 72 nights required to reach <S/N>=40 • TOTAL: Spectra of 56,826 regions across the disks of 30 nearby spiral galaxies.

20. The VENGA survey BLUE SPECTRUM [OII] Ca H+K Hη Hδ Hγ Hζ RED SPECTRUM Fe5015 [OII] Hβ Hα+[NII] [SII] [OIII] Mg b

21. Example: M51a SFR H2 HI SFRE log(O/H) E(B-V) HST V-band A/K ΔV

22. Science Projects • The Star Formation Rate across the Disks of Normal Spirals (Blanc, Heiderman, Gebhardt, Evans) • Constraining Galaxy Merger and Bulge Assembly History (Weinzirl, Jogee) • Structure, Morphology, and Parameter Correlations among Families of Bulges(Fisher, Fabricius, Drory) • Constraints on bar-driven galaxy evolution with VIRUS-P (Marinova, Jogee) • Edge-on Galaxies: Thick Disk Stars and the Diffuse Ionized Medium (Yoachim, Blanc) • Probing AGN Fueling with VIRUS-P (Hao, her students) • The O/H Gas Abundance Gradient in Nearby Spirals (Blanc)

23. Papers • Publications • "The Spatially Resolved Star Formation Law from Integral Field Spectroscopy: VIRUS-P Observations of NGC 5194" , Guillermo A. Blanc, Amanda Heiderman, Karl Gebhardt, Neal J. Evans II, and Joshua Adams (2009, ApJ, 704, 842) • Papers in Preparation • "Gas Kinematics and Star Formation in Barred Spirals", Irina Marinova et al. • "Assembly of Bulges: Constraints from Structure, Stellar Populations, and Metallicity", Tim Weinzirl et al. • "The Metallicity Dependence of the Molecular Gas Fraction in Nearby Spirals", Guillermo A. Blanc et al.

24. Examples The Spatially Resolved Star Formation Law from Integral Field Spectroscopy: VIRUS-P Observations of NGC 5194 (2009, ApJ, 704, 842) Integral Field Unit Spectroscopy of the stellar disk truncation region of NGC 6155 (2010, ApJL, 716, 4)

25. Example I: M51a

26. Example I: M51a

27. Example I: M51a Measurement • THING  HI • BIMA SONG  CO  H2 • VENGA Emission lines  SFR • Subtract photospheric absorption lines and continuum; • Correct dust extinction (Hα/Hβ); • Remove “AGN affected” region (BPT & r<600pc) • Correct DIG

28. Example I: M51a Spatially Resolved Star Formation Law

30. Example I: M51a Spatially Resolved Star Formation Law

31. Example II: NGC 6155 Stellar disk truncation region of NGC 6155

32. Example II: NGC 6155 Stellar population synthesis

33. Summary • VENGA will provide 2D mapping of Gas & Stellar kinematics SFR & stellar populations (star formation rate history) Chemical abundances ISM density & ionization states Emission line fluxes and ratios Dust extinction • We will be able to spatially correlate all these quantities. • This extensive dataset will allow a wide range of studies in galaxy formation and evolution: Star Formation Structure Assembly Stellar Populations Chemical evolution Gas and Stellar Dynamics ISM structure Accretion and Feedback

34. Thank You!