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Charting Cosmic Flows into the Zone of Avoidance: The Overdensity in Vela

Charting Cosmic Flows into the Zone of Avoidance: The Overdensity in Vela . R. Kraan-Korteweg , T. Jarrett, M. Cluver , M. Bilicki , H. Jones, M. Colless. The Local Universe.

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Charting Cosmic Flows into the Zone of Avoidance: The Overdensity in Vela

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  1. Charting Cosmic Flows into the Zone of Avoidance: The Overdensity in Vela R. Kraan-Korteweg, T. Jarrett, M. Cluver, M. Bilicki, H. Jones, M. Colless

  2. The Local Universe Panoramic view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way. The image is derived from the 2MASS Extended Source Catalog (XSC)--more than 1.5 million galaxies, and the Point Source Catalog (PSC)--nearly 0.5 billion Milky Way stars. The map is projected with an equal area Aitoff in the Galactic system (Milky Way at center). Jarrett 2004

  3. The Local Universe Panoramic view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way. The image is derived from the 2MASS Extended Source Catalog (XSC)--more than 1.5 million galaxies, and the Point Source Catalog (PSC)--nearly 0.5 billion Milky Way stars. The map is projected with an equal area Aitoff in the Galactic system (Milky Way at center). Jarrett 2004

  4. Vela Overdensity Galaxies observed behind the Hydra-Antlia-Vela region of the Milky Way, projected in Galactic coordinates. The cyan dots are the on-sky distribution of galaxies with known redshifts between 16000 and 22000 km/s from the 6dFGS . The blue stars indicate where two CIZA galaxy clusters are found.

  5. Vela Overdensity

  6. Spectra Observations/Strategy AAT: AAOMEGA SALT: RSS-MOS --- target high extinction regions where the AAT lacks the mojo 2MRS: J. Huchra Legacy: Lucas Macri (UT A/M) • Spectro-Imaging (multi-lambda) • WISE & VISTA (photozs) • Pathfinders (WALLABY)

  7. RSS-MOS: 10 masks targeted 40% Data Acquired to Date Huge Thanks to: Alexei Kniazev, Petri Vaisanen & David Gilbank SALT Observations

  8. SALT Observations

  9. One Target Field (Block): Exposure: 375 sec Visits: 2 SALT Observations

  10. RSS-MOS Data Reduction: 0. inputs: “mbxgp” 2-D spectral cubes (2 in total), wavelength calibration “arc” -- Argon, RSMT file (target coords) Python Script (D. Gilbank): apply wavelength calibration, extract slit-lits, create indiv. fits files Clean cosmic rays (python script, see next page) combine (2) epochs Improve wavelength calibration using skylines and cubic fit Extract 1-D spectrum: collapse spatial info, remove local sky Determine redshift SALT Reductions

  11. SALT Reductions LACosmic – python script based on Pieter van Dokkum's L.A.Cosmic algorithm c = cosmics.cosmicsimage(array, gain=2.2, readnoise=10.0, sigclip = 4.0, sigfrac = 0.3, objlim = 3.0)

  12. Beware !

  13. Yellow == (skewed) sky lines; blue == desired sky line locations SALT Observations

  14. Deflection (Angstrom) versus Wavelength

  15. Yellow == (skewed) sky lines; blue == desired sky line locations SALT Observations

  16. SALT Results

  17. 4 MOS Fields -- ~ 40 target galaxies 3 emission lines detected 21 absorption line systems SALT Results

  18. Even this tiny amount of data indicates that the SALT redshift results are very encouraging – targeted galaxies appear to belong to the overdensities painted by our multi-l datasets, bridging the ZoA. This suggests that the Local Universe great attractors might be connected on an unprecedented scale – in the form of an enormous ring/shell of galaxies/filaments/clusters/superclusters. This poten- tially massive overdensity might provide the missing clue in the unsettled dipole results. SALT Results

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