J/A+A/634/A97 VUDS UV and Lyα luminosity functions (Khusanova+, 2020)
UV and Lyα luminosity functions of galaxies and star formation rate
density at the end of HI reionization from the VIMOS UltraDeep Survey (VUDS).
Khusanova Y., Le Fevre O., Cassata P., Cucciati O., Lemaux B.C.,
Tasca L.A.M., Thomas R., Garilli B., Le Brun V., Maccagni D.,
Pentericci L., Zamorani G., Amorin R., Bardelli S., Castellano M.,
Cassara L.P., Cimatti A., Giavalisco M., Hathi N.P., Ilbert O.,
Koekemoer A.M., Marchi F., Pforr J., Ribeiro B., Schaerer D., Tresse L.,
Vergani D., Zucca E.
<Astron. Astrophys., 634, A97 (2020)>
=2020A&A...634A..97K 2020A&A...634A..97K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Redshifts ; Ultraviolet
Keywords: galaxies: high-redshift - galaxies: evolution - galaxies: formation -
galaxies: star formation - dark ages, reionization, first stars -
galaxies: luminosity function, mass function
Abstract:
The star formation rate density (SFRD) evolution presents an
area of great interest in the studies of galaxy evolution and
reionization. The current constraints of SFRD at z>5 are based on the
rest-frame UV luminosity functions with the data from photometric
surveys. The VIMOS UltraDeep Survey (VUDS) was designed to observe
galaxies at redshifts up to ∼6 and opened a window for measuring SFRD
at z>5 from a spectroscopic sample with a well-controlled selection
function.
We establish a robust statistical description of the star-forming
galaxy population at the end of cosmic HI reionization (5.0≤z≤6.6)
from a large sample of 49 galaxies with spectroscopically confirmed
redshifts. We determine the rest-frame UV and Lyα luminosity
functions and use them to calculate SFRD at the median redshift of our
sample z=5.6.
We selected a sample of galaxies at 5.0≤zspec≤6.6 from the VUDS.
We cleaned our sample from low redshift interlopers using ancillary
photometric data. We identified galaxies with Lyα either in
absorption or in emission, at variance with most spectroscopic samples
in the literature where Lyα emitters (LAE) dominate. We
determined luminosity functions using the 1/Vmax method.
The galaxies in this redshift range exhibit a large range in their
properties. A fraction of our sample shows strong Lyα emission,
while another fraction shows Lyα in absorption. UV-continuum
slopes vary with luminosity, with a large dispersion. We find that
star-forming galaxies at these redshifts are distributed along the
main sequence in the stellar mass vs. SFR plane, described with a
slope α=0.85±0.05. We report a flat evolution of the specific
SFR compared to lower redshift measurements. We find that the UV
luminosity function is best reproduced by a double power law, while a
fit with a Schechter function is only marginally inferior. The
Lyα luminosity function is best fitted with a Schechter
function. We derive a
logSFRDUV(M☉/yr/Mpc3)=-1.45+0.06-0.08 and
logSFRDLyα(M☉/yr/Mpc3)=-1.40+0.07-0.08. The SFRD
derived from the Lyα luminosity function is in excellent
agreement with the UV-derived SFRD after correcting for IGM
absorption.Conclusions. Our new SFRD measurements at a mean redshift
of z=5.6 are ∼0.2dex above the mean SFRD reported in Madau & Dickinson
(2014ARA&A..52..415M 2014ARA&A..52..415M), but in excellent agreement with results from
Bouwens et al. (2015ApJ...803...34B 2015ApJ...803...34B). These measurements confirm the
steep decline of the SFRD at z>2. The bright end of the Lyα
luminosity function has a high number density, indicating a
significant star formation activity concentrated in the brightest LAE
at these redshifts. LAE with equivalent width EW>25Å contribute to
about 75% of the total UV-derived SFRD. While our analysis favors low
dust content in 5.0<z<6.6, uncertainties on the dust extinction
correction and associated degeneracy in spectral fitting will remain
an issue, when estimating the total SFRD until future surveys
extending spectroscopy to the NIR rest-frame spectral domain, such as
with JWST.
Description:
A sample of 49 galaxies spectroscopically confirmed at redshifts
5.0<z<6.6 is presented and simultaneously statistically robust
constraints on the bright end of the Lyα and UV luminosity
functions are given. The galaxies were carefully selected using several
criteria, including redshift verification, ensuring high completeness
and purity. This work extends the results previously obtained to the
highest redshifts probed by spectroscopic surveys (Cassata et al.
2011A&A...525A.143C 2011A&A...525A.143C; Tasca et al. 2015A&A...581A..54T 2015A&A...581A..54T).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 111 49 Physical parameters of galaxies in our sample
tablea2.dat 79 49 Summary of the selection criteria
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See also:
J/A+A/600/A110 : VIMOS Ultra Deep Survey (VUDS) DR1 (Tasca+, 2017)
http://cesam.lam.fr/vuds : VUDS Home Page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galaxy name
15- 20 F6.4 --- zsp Spectroscopic redshift
22- 23 I2 --- Flag Flag (G1)
25- 31 F7.3 mag MFUV ? Absolute FUV magnitude
33- 38 F6.2 10-20W/m2/nm FLya ? Lymanα flux
(in 10-16erg/s/cm2/Å)
40- 43 F4.2 10-20W/m2/nm E_FLya ? Error on FLya (upper value)
45- 49 F5.2 10-20W/m2/nm e_FLya ? Error on FLya (lower value)
51- 55 F5.1 --- S/NEL ? Signal-to-noise ratio
57- 61 F5.1 Myr Age ? Age
63- 67 F5.1 Myr E_Age ? Error on Age (upper value)
69- 73 F5.1 Myr e_Age ? Error on Age (lower value)
75- 78 F4.1 [Msun] logMass ? Mass
80- 82 F3.1 [Msun] E_logMass ? Error on Mass (upper value)
84- 86 F3.1 [Msun] e_logMass ? Error on Mass (lower value)
88- 90 F3.1 Msun/yr logSFR ? Star formation rate
92- 94 F3.1 Msun/yr E_logSFR ? Error on logSFR (upper value)
96- 98 F3.1 Msun/yr e_logSFR ? Error on logSFR (lower value)
100-103 F4.1 [1/Gyr] logsSFR ? Specific star formation rate
105-107 F3.1 [1/Gyr] E_logsSFR ? Error on logsSFR (upper value)
109-111 F3.1 [1/Gyr] e_logsSFR ? Error on logsSFR (lower value)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/49] Sequential number
4- 14 A11 --- Name Galaxy name
16- 21 F6.4 --- zsp Spectroscopic redshift
23- 24 I2 --- Flag Flag (G1)
26- 28 A3 --- Codea [Yes/No -] No detection below 912Å
30- 32 A3 --- Codeb [Yes/No -] No or faint detection between
912Å and Lyα
34- 36 A3 --- Codec [Yes/No -] At least one detection at position
of Lyα or after Lyα
38- 42 F5.2 --- dz/sigma ? Redshift error to redshift dispersion ratio
44- 49 F6.2 --- chi2 ? chi2 value
51- 53 A3 --- Coded [Yes/No -] Signs of contamination in
photometry or bad sky subtraction
55- 79 A25 --- Com Comments
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Global notes:
Note (G1): Flag as follows:
1 = 50-75% redshift reliability
2 = 75-85% redshift reliability
3 = 85-95% redshift reliability
4 = 95-100% redshift reliability
9 = ∼80% redshift reliability
14 = 50-75% and 95-100% redshift reliability
29 = 75-85% and ∼80% redshift reliability
39 = 85-95% and ∼80% redshift reliability
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 02-May-2020