UV CONTINUUM SLOPE AND DUST OBSCURATION FROM z ∼ 6 TO z ∼ 2: THE STAR FORMATION RATE DENSITY AT HIGH REDSHIFT

By R. Bouwens, G. Illingworth, M. Franx, R. Chary, G. Meurer, Christopher J. Conselice, H. C. Ford, M. Giavalisco, P. V. van Dokkum. 2009

336 citations recorded by the source corpus.

We provide a systematic measurement of the rest-frame UV continuum slope β over a wide range in redshift (z ∼ 2–6) and rest-frame UV luminosity (0.1 L*z = 3 to 2 L*z = 3) to improve estimates of the star formation rate (SFR) density at high redshift. We utilize the deep optical and infrared data (Advanced Camera for Surveys/NICMOS) over the Chandra Deep Field-South and Hubble Deep Field-North Great Observatories Origins Deep Survey fields, as well as the UDF for our primary UBVi “dropout” Lyman Break Galaxy sample. We also use strong lensing clusters to identify a population of very low luminosity, high-redshift dropout galaxies. We correct the observed distributions for both selection biases and photometric scatter. We find that the UV-continuum slope of the most luminous galaxies is substantially redder at z ∼ 2–4 than it is at z ∼ 5–6 (from ∼−2.4 at z ∼ 6 to ∼−1.5 at z ∼ 2). Lower luminosity galaxies are also found to be bluer than higher luminosity galaxies at z ∼ 2.5 and z ∼ 4. We do not find a large number of galaxies with β's as red as −1 in our dropout selections at z ∼ 4, and particularly at z ≳ 5, even though such sources could be readily selected from our data (and also from Balmer Break Galaxy searches at z ∼ 4). This suggests that star-forming galaxies at z ≳ 5 almost universally have very blue UV-continuum slopes, and that there are not likely to be a substantial number of dust-obscured galaxies at z ≳ 5 that are missed in “dropout” searches. Using the same relation between UV-continuum slope and dust extinction as has been found to be appropriate at both z ∼ 0 and z ∼ 2, we estimate the average dust extinction of galaxies as a function of redshift and UV luminosity in a consistent way. As expected, we find that the estimated dust extinction increases substantially with cosmic time for the most UV luminous galaxies, but remains small (≲2 times) at all times for lower luminosity galaxies. Because these same lower luminosity galaxies dominate the luminosity density in the UV continuum, the overall dust extinction correction remains modest at all redshifts and the evolution of this correction with redshift is only modest. We include the contribution from ultra-luminous IR galaxies in our SFR density estimates at z ∼ 2–6, but find that they contribute only ∼20% of the total at z ∼ 2.5 and ≲10% at z ≳ 4.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/194f307ce67741f0369f5d7dc99204472b0be9aa

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

THE 2012 HUBBLE ULTRA DEEP FIELD (UDF12): OBSERVATIONAL OVERVIEW (2012, background): “…variety of results have been obtained on the ultraviolet spectral slopes and stellar populations of these early star-forming galaxies at z∼ 7− 8 (Bouwens et al. 2009, 2010, 2012, Ono et al. 2010, Bunker et al. 2010, Finkelstein et al. 2010, 2012b,a, Yan et al. 2011b,a, McLure et al. 2010,…”
CALIBRATING EXTINCTION-FREE STAR FORMATION RATE DIAGNOSTICS WITH 33 GHz FREE–FREE EMISSION IN NGC 6946 (2011, neutral): “10 13 L⊙ (e.g., Chary & Elbaz 2001; Takeuchi et al. 2005; Bouwens et al. 2009; Murphy et al. 2011).”
UV-CONTINUUM SLOPES OF >4000 z ∼ 4–8 GALAXIES FROM THE HUDF/XDF, HUDF09, ERS, CANDELS-SOUTH, AND CANDELS-NORTH FIELDS (2013, methodology): “In Figure 9, the observed trends are compared with our z ∼ 7 results from §3, z ∼ 1-6 results from the literature (Labbe et al. 2009; Bouwens et al. 2009; Bouwens et al. 2012), and also with the hydrodynamical simulation results from Finlator et al. (2011).”
The rising star formation histories of distant galaxies and implications for gas accretion with time (2010, background): “3, observations suggest that there exist both infrared luminous and UVluminous star-forming galaxies (e.g., Papovich et al. 2006), which make a substantial contribution to the cosmic SFR history (e.g., Reddy et al. 2008; Bouwens et al. 2009).”
Star formation sustained by gas accretion (2014, background): “Various symbols correspond to various sources in the literature as detailed in the paper by Bouwens et al. (2011) from which the plot was taken”
GOODS-Herschel: dust attenuation properties of UV selected high redshift galaxies (2012, background): “At higher redshift, from studies of the slope of the UV continuum, Bouwens et al. (2009) and Lee et al. (2011) also found a decrease of the dust attenuation with the absolute UV magnitude.”
Galaxy luminosities, stellar masses, sizes, velocity dispersions as a function of morphological type (2009, methodology): “Bouwens et al. (2009) have recently calibrated the SFR over the range 2 <z < 6 using deep optical and infrared data from Advanced Camera for Surveys (ACS)/Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in the GOODS fields, UBVi dropout Lyman break galaxies and ultraluminous infrared…”
UVUDF: ULTRAVIOLET THROUGH NEAR-INFRARED CATALOG AND PHOTOMETRIC REDSHIFTS OF GALAXIES IN THE HUBBLE ULTRA DEEP FIELD (2015, background): “…et al. 2013; McLure et al. 2013; Oesch et al. 2013; Bouwens et al. 2014), to observe the evolution in the star formation rate density (e.g., Bouwens et al. 2007, 2009, 2010), to determine the morphological properties of galaxies (e.g., Bouwens et al. 2004; Elmegreen et al. 2005c; Straughn…”
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 (2011, methodology): “…UV color provides us with perhaps our best means for estimating the dust extinction and star formation rate (SFR) for faint z > 3 galaxies, given that other techniques for probing the SFR tend to only detect the most bolometrically luminous galaies (e.g., Bouwens et al. 2009; Smit et al. 2012).”
Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, background): “Several studies showed that these galaxies have bluer UV-continuum slopes than their more massive counterparts (Bouwens et al. 2009, 2012, 2014), with no significant redshift evolution.”
The UV continua and inferred stellar populations of galaxies at z ~7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign (2012, background): “…redshift (from z 4 to z 7) in terms of monotonically decreasing average dust extinction, with important implications for the inferred cosmological evolution of star-formation activity (e.g. Hathi, Malhotra & Rhoads 2008; Bouwens et al. 2009, 2012; Castellano et al. 2012; Finkelstein et al. 2012).”
Galactic star formation and accretion histories from matching galaxies to dark matter haloes (2012, methodology): “This comparison includes estimates derived from the UV (Salim et al. 2007; van der Burg et al. 2010; Bouwens et al. 2009; Robotham & Driver 2011; Bouwens et al. 2011; Cucciati et al. 2012), Hα (Ly et al. 2011), both UV and IR (Zheng et al. 2007), the FIR (Rujopakarn et al. 2010) and from radio…”
Planck 2013 results. XXX. Cosmic infrared background measurements and implications for star formation (2013, background): “Currently, most of the measurements rely on the UV light emerging from the high-redshift galaxies themselves (e.g., Bouwens et al. 2009; Cucciati et al. 2012).”
Herschel PEP/HerMES: the redshift evolution (0 ≤ z ≤ 4) of dust attenuation and of the total (UV+IR) star formation rate density (2013, background): “Finally, higher redshift AFUV from the UV slope, β, suggest a continuous decline at least up to z = 6 (Bouwens et al.(2009)).”
THE EVOLUTION OF GALAXY NUMBER DENSITY AT z < 8 AND ITS IMPLICATIONS (2016, background): “This is an interesting question as we know that the star formation rate rises, and then declines at z < 8 (e.g., Bouwens et al. 2009; Duncan et al. 2014; Madau & Dickinson 2014), while at the same time galaxies become larger and less peculiar (e.g., Conselice et al. 2004; Papovich et al. 2005;…”
PHYSICAL CONDITIONS IN A YOUNG, UNREDDENED, LOW-METALLICITY GALAXY AT HIGH REDSHIFT (2010, positive): “At increasing redshifts, the UV-continuum slope β (fλ ∝ λ β) of galaxies becomes bluer; the most luminous galaxies have β ∼ −1.5 at z ∼ 2, and β ∼ −2.4 at z ∼ 6 (Bouwens et al. 2009).”
ON THE REDSHIFT EVOLUTION OF THE Lyα ESCAPE FRACTION AND THE DUST CONTENT OF GALAXIES (2010, methodology): “The red line (fit to these data) runs slightly flatter than the black one (combined fits from the previous sections) and suggests a slightly higher EB−V , and and therefore dust content, than measured at the highest redshifts in Bouwens et al. (2009a).”
A critical analysis of the ultraviolet continuum slopes (β) of high-redshift galaxies: no evidence (yet) for extreme stellar populations at z > 6 (2011, methodology): “However, this luminosity dependence takes the average value of UV slope from〈β〉 ≃ −1.3 at MUV = −22.2 to 〈β〉 ≃ −1.9 at MUV = −17.2, and is attributed by Bouwens et al. (2009) as being primarily a resultof decreasing dust obscuration with decreasing UV luminosity(see also Stark et al. 2010).”