Journal article

UV-CONTINUUM SLOPES AT z similar to 4-7 FROM THE HUDF09 ERS CANDELS OBSERVATIONS: DISCOVERY OF A WELL-DEFINED UV COLOR-MAGNITUDE RELATIONSHIP FOR z >= 4 STAR-FORMING GALAXIES

RJ Bouwens, GD Illingworth, PA Oesch, M Franx, I Labbe, M Trenti, P van Dokkum, CM Carollo, V Gonzalez, R Smit, D Magee

The Astrophysical Journal | IOP PUBLISHING LTD | Published : 2012

Abstract

Ultra-deep Advanced Camera for Surveys (ACS) and WFC3/IR HUDF+HUDF09 data, along with the wide-area GOODS+ERS+CANDELS data over the CDF-S GOODS field, are used to measure UV colors, expressed as the UV-continuum slope β, of star-forming galaxies over a wide range of luminosity (0.1L* to 2L* ) at high redshift (z ∼ 7 to z ∼ 4). β is measured using all ACS and WFC3/IR passbands uncontaminated by Lyα and spectral breaks. Extensive tests show that our β measurements are only subject to minimal biases. Using a different selection procedure, Dunlop et al. recently found large biases in their β measurements. To reconcile these different results, we simulated both approaches and found that β measu..

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University of Melbourne Researchers

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Funding Acknowledgements

We are happy to thank Romeel Dave, Pratika Dayal, Harry Ferguson, Kristian Finlator, Steve Finkelstein, Mauro Giavalisco, Roderik Overzier, Casey Papovich, Naveen Reddy, Daniel Schaerer, Daniel Stark, and Simone Weinmann for useful discussions. We are greatly appreciative to Kristian Finlator for analyzing the UV-continuum slope distribution in his cosmological hydrodynamical simulations and providing us with the quantitative results. Massimo Stiavelli and Kristian Finlator provided us with helpful feedback on our manuscript. We acknowledge our referee Naveen Reddy for his extensive feedback on our initial submission, which was very useful to us in improving the overall clarity and rigor of this manuscript. We are grateful to all those at NASA, STScI, and throughout the community who have worked so diligently to make Hubble the remarkable observatory that it is today. We acknowledge the support of the NASA grant NAG5-7697, the NASA grant HST-GO-11563, and the ERC grant HIGHZ 227749; P.O. acknowledges support from NASA through a Hubble Fellowship grant 51278.01 awarded by the Space Telescope Science Institute.