UV-CONTINUUM SLOPES AT z ∼ 4-7 FROM THE HUDF09+ERS+CANDELS OBSERVATIONS: DISCOVERY OF A WELL-DEFINED UV COLOR-MAGNITUDE RELATIONSHIP FOR z ⩾ 4 STAR-FORMING GALAXIES

• Published in: The Astrophysical journal Vol. 754; no. 2; pp. 83 - 33
• Main Authors: Bouwens, R. J., Illingworth, G. D., Oesch, P.A., Franx, M., Labbé, I., Trenti, M., van Dokkum, P., Carollo, C. M., González, V., Smit, R., Magee, D.
• Format: Journal Article
• Language: English
• Published: Bristol IOP 01.08.2012
• Subjects: ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CAMERAS; COLOR; COSMIC DUST; DENSITY; Earth, ocean, space; Exact sciences and technology; GALAXIES; LUMINOSITY; LYMAN LINES; MASS; RED SHIFT; Simulation; Slopes; STAR EVOLUTION; Star formation; Star formation rate; STARS; ULTRAVIOLET RADIATION; Continuum; Galaxy evolution; Red shift; Star formation; Galaxies; Stellar mass; galaxies: evolution; Color; Luminosity; Formation rate; galaxies: high-redshift
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/754/2/83

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 beta , of star-forming galaxies over a wide range of luminosity (0.1L* sub(z)=3 to 2L* sub(z=3)) at high redshift (z ~ 7 to z ~ 4). To reconcile these different results, we simulated both approaches and found that beta measurements for faint sources are subject to large biases if the same passbands are used both to select the sources and to measure beta . Inclusion of the new dust extinction results leads to (1) excellent agreement between the star formation rate (SFR) density at z ~ 4-8 and that inferred from the stellar mass density; and (2) to higher specific star formation rates (SSFRs) at z [gap] 4, suggesting that the SSFR may evolve modestly (by factors of ~2) from z ~ 4-7 to z ~ 2.