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Post Info TOPIC: NEWFIRM Medium-band Survey
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RE: NEWFIRM Medium-band Survey
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Astronomers Discover That Galaxies Are Either Asleep or Awake

Astronomers have probed into the distant universe and discovered that galaxies display one of two distinct behaviours: they are either awake or asleep, actively forming stars or are not forming any new stars at all.
Scientists have known for several years that galaxies in the nearby universe seem to fall into one of these two states. But a new survey of the distant universe shows that even very young galaxies as far away as 12 billion light years are either awake or asleep as well, meaning galaxies have behaved this way for more than 85 percent of the history of the universe. (Looking at galaxies farther away is like looking back in time when they were much younger, because of how long it takes the light they emit to reach us here on Earth.)
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Title: The NEWFIRM Medium-band Survey: Photometric Catalogues, Redshifts and the Bimodal Colour Distribution of Galaxies out to z~3
Authors: Katherine E. Whitaker, Ivo Labbe, Pieter G. van Dokkum, Gabriel Brammer, Mariska Kriek, Danilo Marchesini, Ryan F. Quadri, Marijn Franx, Adam Muzzin, Rik J. Williams, Rachel Bezanson, Garth D. Illingworth, Kyoung-Soo Lee, Britt Lundgren, Erica J. Nelson, Gregory Rudnick, Tomer Tal, David A. Wake

We present deep near-infrared (NIR) medium-bandwidth photometry over the wavelength range 1-1.8 microns in the All-wavelength Extended Groth strip International Survey (AEGIS) and Cosmic Evolution Survey (COSMOS) fields. The observations were carried out as part of the NEWFIRM Medium-Band Survey (NMBS), an NOAO survey program on the Mayall 4m telescope on Kitt Peak using the NOAO Extremely Wide-Field Infrared Imager (NEWFIRM). In this paper, we describe the full details of the observations, data reduction and photometry for the survey. We also present a public K-selected photometric catalogue, along with accurate photometric redshifts. The redshifts are computed with 37 (20) filters in the COSMOS (AEGIS) fields, combining the NIR medium-bandwidth data with existing ultraviolet (UV; Galaxy Evolution Explorer), visible and NIR (Canada-France-Hawaii Telescope and Subaru) and mid-IR (Spitzer/IRAC) imaging. We find excellent agreement with publicly available spectroscopic redshifts, with sigma_z/(1+z)~1-2% for ~4000 galaxies at z=0-3. The NMBS catalogues contain ~13,000 galaxies at z>1.5 with accurate photometric redshifts and rest-frame colours. Due to the increased spectral resolution obtained with the five NIR medium-band filters, the median 68% confidence intervals of the photometric redshifts of both quiescent and star-forming galaxies are a factor of ~2 times smaller when comparing catalogues with medium-band NIR photometry to NIR broadband photometry. We show evidence for a clear bimodal colour distribution between quiescent and star-forming galaxies that persists to z~3, a higher redshift than has been probed so far.

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