Browsing by Subject "eso imaging survey"

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    Optical Spectroscopy Of X-Ray Sources In The Extended Chandra Deep Field South
    (2009-03) Treister, Ezequiel; Virani, Shanil; Gawiser, Eric; Urry, C. Megan; Lira, Paulina; Francke, Ilarold; Blanc, Guillermo A.; Cardamone, Carolin N.; Damen, Maaike; Taylor, Edward N.; Schawinski, Kevin; Blanc, Guillermo A.
    We present the first results of our optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South. A total of 339 sources were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray sources, including archival data and a literature search. We find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley." The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity.
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    A Public, K-Selected, Optical-to-Near-Infrared Catalog of the Extended Chandra Deep Field South (ECDFS) from the Multiwavelength Survey by Yale-Chile (MUSYC)
    (2009-08) Taylor, Edward N.; Franx, Marijn; van Dokkum, Pieter G.; Quadri, Ryan F.; Gawiser, Eric; Bell, Eric F.; Barrientos, L. Felipe; Blanc, Guillermo A.; Castander, Francisco J.; Damen, Maaike; Gonzalez-Perez, Violeta; Hall, Patrick B.; Herrera, David; Hildebrandt, Hendrik; Kriek, Mariska; Labbe, Ivo; Lira, Paulina; Maza, Jose; Rudnick, Gregory; Treister, Ezequiel; Urry, C. Megan; Willis, Jon P.; Wuyts, Stijn; Blanc, Guillermo A.
    We present a new, K-selected, optical-to-near infrared photometric catalog of the Extended Chandra Deep Field South (ECDFS), making it publicly available to the astronomical community.(22) The data set is founded on publicly available imaging, supplemented by original z' JK imaging data collected as part of the MUltiwavelength Survey by Yale-Chile (MUSYC). The final photometric catalog consists of photometry derived from U U (38) BVRIz' JK imaging covering the full 1/2 x 1/2 square degrees. of the ECDFS, plus H-band photometry for approximately 80% of the field. The 5 sigma flux limit for point sources is K(tot)((AB)) = 22.0. This is also the nominal completeness and reliability limit of the catalog: the empirical completeness for 21.75 < K < 22.00 is greater than or similar to 85%. We have verified the quality of the catalog through both internal consistency checks, and comparisons to other existing and publicly available catalogs. As well as the photometric catalog, we also present catalogs of photometric redshifts and rest-frame photometry derived from the 10-band photometry. We have collected robust spectroscopic redshift determinations from published sources for 1966 galaxies in the catalog. Based on these sources, we have achieved a (1 sigma) photometric redshift accuracy of Delta z/(1 + z) = 0.036, with an outlier fraction of 7.8%. Most of these outliers are X-ray sources. Finally, we describe and release a utility for interpolating rest-frame photometry from observed spectral energy distributions, dubbed InterRest.(23)