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J/ApJ/793/115    UV-continuum slopes beta for z∼4-8 galaxies    (Bouwens+, 2014)

UV-continuum slopes of >4000 z∼4-8 galaxies from the HUDF/XDF, HUDF09, ERS, CANDELS-south, and CANDELS-north fields. Bouwens R.J., Illingworth G.D., Oesch P.A., Labbe I., van Dokkum P.G., Trenti M., Franx M., Smit R., Gonzalez V., Magee D. <Astrophys. J., 793, 115 (2014)> =2014ApJ...793..115B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, HST ; Photometry, ultraviolet ; Redshifts Keywords: galaxies: evolution; galaxies: high-redshift Abstract: We measure the UV-continuum slope β for over 4000 high-redshift galaxies over a wide range of redshifts z∼4-8 and luminosities from the HST HUDF/XDF, HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new β results reach very faint levels at z∼4 (-15.5 mag: 0.006 Lz=3*), z∼5 (-16.5 mag: 0.014 Lz=3*), and z∼6 and z∼7 (-17 mag: 0.025 Lz=3*). Inconsistencies between previous studies led us to conduct a comprehensive review of systematic errors and develop a new technique for measuring β that is robust against biases that arise from the impact of noise. We demonstrate, by object-by-object comparisons, that all previous studies, including our own and those done on the latest HUDF12 data set, suffered from small systematic errors in β. We find that after correcting for the systematic errors (typically Δβ∼0.1-0.2) all β results at z∼7 from different groups are in excellent agreement. The mean β we measure for faint (-18 mag: 0.1Lz=3*) z∼4, z∼5, z∼6, and z∼7 galaxies is -2.03±0.03±0.06 (random and systematic errors), -2.14±0.06±0.06, -2.24±0.11±0.08, and -2.30±0.18±0.13, respectively. Our new β values are redder than we have reported in the past, but bluer than other recent results. Our previously reported trend of bluer β's at lower luminosities is confirmed, as is the evolution to bluer β's at high redshifts. β appears to show only a mild luminosity dependence faintward of M_UV, AB_~-19 mag, suggesting that the mean β asymptotes to ~-2.2 to -2.4 for faint z≥4 galaxies. At z∼7, the observed β's suggest non-zero, but low dust extinction, and they agree well with values predicted in cosmological hydrodynamical simulations. Description: To accurately quantify the UV-continuum slope of galaxies as a function of luminosity, we require observations over a wide range in depths. These include both the very deep observations over the XDF that extend to very faint luminosities in 9 bands from B435 to H160 and the deep, wide-area observations over CANDELS that provide statistically useful samples of the rarer bright galaxies. Our deepest data set, the ∼4.7 arcmin2 XDF, incorporates all available WFC3/IR observations from the HUDF09, HUDF12, and CANDELS programs, including ∼100 orbit Y105-band, ∼40 orbit J125-band, 30 orbit JH140-band, and ∼85 orbit H160-band observations. Importantly, the current XDF data set includes all of the available observations in the J125 and H160 bands over the HUDF, thereby providing the strongest possible constraints on the UV-continuum slopes β of star-forming galaxies at z∼4-8. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table8.dat 67 4213 A complete list of the UV-continuum slopes beta measures for sources in our z∼4, z∼5, z∼6, z∼7, and z∼8 samples table9.dat 102 4213 Complete set of flux measurements used to derive beta for our z∼4, z∼5, z∼6, z∼7, and z∼8 samples
See also: J/ApJ/653/53 : z∼6 galaxies UV luminosity function (Bouwens+, 2006) J/AJ/141/14 : HST WFC3 ERS : emission-line galaxies (Straughn+, 2011) J/ApJ/743/146 : HST/WFC3 observations in HUDF and GOODS-S (Cameron+, 2011) J/ApJ/756/164 : UV galaxies in CANDELS from z=8 to z=4 (Finkelstein+, 2012) J/MNRAS/453/1136 : XDF CHEF photometric catalogue (Jimenez-Teja+, 2015) Byte-by-byte Description of file: table8.dat
Bytes Format Units Label Explanations
1- 20 A20 --- ID Source ID 22- 23 I2 h RAh Hour of Right Ascension (J2000) 25- 26 I2 min RAm Minute of Right Ascension (J2000) 28- 32 F5.2 s RAs Second of Right Ascension (J2000) 34 A1 --- DE- Sign of the Declination (J2000) 35- 36 I2 deg DEd Degree of Declination (J2000) 38- 39 I2 arcmin DEm Arcminute of Declination (J2000) 41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000) 47- 52 F6.2 mag UVMag Absolute AB magnitude in the Rest-frame UV 54- 58 F5.2 --- beta UV-continuum slope beta 60- 63 F4.2 --- e_beta Uncertainty in the UV-continuum slope beta 65 I1 --- rset [4/8] Sample (1) 67 I1 --- dset [1/4] Data Set (2)
Note (1): The mean redshift of the sample in which the source was found. Note (2): The data set from which the source was selected and in which its UV-continuum slope beta was derived. Referenced as follows: 1 = HUDF/XDF (Illingworth et al. 2013ApJS..209....6I); 2 = HUDF09-1 (Bouwens et al. 2011ApJ...737...90B); 3 = HUDF09-2 (Bouwens et al. 2011ApJ...737...90B); 4 = CANDELS/ERS (Grogin et al. 2011ApJS..197...35G ; Koekemoer et al. 2011ApJS..197...36K ; Windhorst et al. 2011ApJS..193...27W).
Byte-by-byte Description of file: table9.dat
Bytes Format Units Label Explanations
1- 20 A20 --- ID Source ID 23- 27 I5 --- iflux ? F775W Flux Measurement; 100 pJy 29- 31 I3 --- e_iflux ? Uncertainty in iflux 33- 37 I5 --- Iflux ? F814W Flux Measurement; 100 pJy 39- 42 I4 --- e_Iflux ? Uncertainty in Iflux 44- 48 I5 --- zflux ? F850LP Flux Measurement; 100 pJy 50- 52 I3 --- e_zflux ? Uncertainty in zflux 54- 58 I5 --- yflux ? F098M Flux Measurement; 100 pJy 60- 62 I3 --- e_yflux ? Uncertainty in yflux 64- 68 I5 --- Yflux ? F105W Flux Measurement; 100 pJy 70- 72 I3 --- e_Yflux ? Uncertainty in Yflux 74- 78 I5 --- Jflux ? F125W Flux Measurement; 100 pJy 80- 82 I3 --- e_Jflux ? Uncertainty in Jflux 84- 88 I5 --- JHflux ? F140W Flux Measurement; 100 pJy 90- 92 I3 --- e_JHflux ? Uncertainty in JHflux 94- 98 I5 --- Hflux ? F160W Flux Measurement; 100 pJy 100-102 I3 --- e_Hflux ? Uncertainty in Hflux
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 19-Apr-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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