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Z-FOURGE - the FourStar Galaxy Evolution Survey

Z-FOURGE - the FourStar Galaxy Evolution Survey. Status Report at the 1.3-year mark. Team. Ivo Labbe (PI) & Caroline Straatman - Leiden Persson, Murphy, Monson, Kelson, McCarthy, Quadri - Carnegie Lee Spitler, Karl Glazebrook , Glenn Kacprzak, Greg Poole - Swinburne

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Z-FOURGE - the FourStar Galaxy Evolution Survey

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  1. Z-FOURGE - the FourStar Galaxy Evolution Survey Status Report at the 1.3-year mark

  2. Team • Ivo Labbe (PI) & Caroline Straatman - Leiden • Persson, Murphy, Monson, Kelson, McCarthy, Quadri - Carnegie • Lee Spitler, Karl Glazebrook, Glenn Kacprzak, Greg Poole - Swinburne • Casey Papovich, Kim-Vy Tran, Vithal Tilvi - Texas A&M • Pieter van Dokkum - Yale

  3. Galaxy evolution at 1 < z < 3.5 • Redshifts and high quality imaging for thousands of galaxies • Redshifts, photometry plus models give the following: • Luminosity and LF • Stellar Mass and MF • Star Formation Rate • Extinction • Formation redshift • Imaging data gives: • Galaxy size • Morphology • Environment

  4. The key: Photometric Redshifts Enable large samples of galaxies (not feasible with NIR spectroscopy) • Observations • Medium bandwidth (/ ~ 10) near-IR filters enable: • z/(1+z) = 0.01 - 0.02 • More accurate photo-z than broadband filters • Existing ground-based optical, Hubble, and Spitzer data • Techniques • 4000 or Balmer break in near-IR, overall SED

  5. Model SEDs and Filters

  6. FourStar Observations • FOV 10.8’ x 10.8’ (4K x 4K) • scale 0.159”/pixel • Six filters: J1, J2, J3, Hs, Hl, plus Ks • ~10 hours per filter • Median seeing in Ks: 0.5” FWHM • Deepest Ks image: 25.4 AB, 5 total for a point source

  7. First result - a z ~ 2.2 cluster in COSMOS(Spitler et al. 2012, ApJ, 148, L21)

  8. Deep Optical HST

  9. FourStar J1,J2,J3

  10. FourStar Ks, 10 hr / ACS I, 1 hr

  11. Data and SED fits(medium bands are red points)

  12. Results • A & B are robust, C slightly less so. Possible overdensity D has the most luminous galaxy in the vicinity. • Spectra of 4 galaxies confirm cluster redshift. • Halo mass estimates 6x, 1x, and 1x 1013 Msun; may grow 10x to z = 0. • Simulations suggest high probability that one or more of ABC will merge by z = 0.

  13. Two interesting objects A Z-band (Ly) dropout at z ~ 7.1 A T7 brown dwarf

  14. Project Status • COSMOS: 13,500 galaxies, 6500 at z > 1, several at z ~ 3.5 (age of universe ~ 1.8 Gyr). • CDF-S: 9,000 galaxies, no large mature cluster detected (expect 1±1 over the three fields). • UDS: next and final field in 2012B. • Upon completion, we will have > 15,000 with z > 1 • Divided into 5 bins of mass, redshift, and environment gives 120/bin => robust statistics

  15. Metal-poor star-forming galaxies [OIII]5007 in J3 filter and H in Hl filter in a RGB display. z ~ 1.5

  16. Results pertaining to this cluster • First, clusters are found by slicing redshift catalog, then using nearest neighbor statistic of Papovich et al. (2010, ApJ, 716, 1503): for each galaxy measure the angular distance to 7th nearest neighbor, then compute the corresponding surface density. • 7, 13, 9 galaxies within 30” of A, B, C in a 2.1 - 2.3 slice (313 total). Different statistical tests indicate that A & B are robust, C slightly less so. E.g., surface densities in adjacent slices are ~ 2.5 arcmin-2

  17. More … • No new large mature cluster in CDF-S; expect 1±1 over the three fields (variance method of Somerville et al. 2004, ApJ 600, L171). 7. Other high-z clusters are either blue protoclusters, e.g., AzTEC-3, or the one mature one of Gobat et al. (2011, A&A, 526, 133), z ~ 2.07. 8. Finally, spectra of 4 galaxies confirm cluster at z = 2.09. (z due to filters)

  18. Observations Three fields: COSMOS, CDF-S, UDS. (these have a large amount of ancillary data (deep optical, Spitzer) and more to come from Alma and Herschel). COSMOS: 70 hours 56 t(eff) hours CDF-S: 45 41 UDS: (50 hopefully)

  19. FourStar vs ACS/HST(Core of A)

  20. Model SEDs and Filters

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