J/ApJ/813/78 z=4.5 and z=5.7 LAEs properties with Spitzer (Finkelstein+, 2015)
Probing the physical properties of z=4.5 Lyman α emitters with Spitzer.
Finkelstein K.D., Finkelstein S.L., Tilvi V., Malhotra S., Rhoads J.E.,
Grogin N.A., Pirzkal N., Dey A., Jannuzi B.T., Mobasher B., Pakzad S.,
Salmon B., Wang J.
<Astrophys. J., 813, 78 (2015)>
=2015ApJ...813...78F 2015ApJ...813...78F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR ; Photometry, RI ; Stars, masses ; Stars, ages ;
Abundances ; Extinction
Keywords: galaxies: evolution - galaxies: high-redshift -
galaxies: stellar content
Abstract:
We present the results from a stellar population modeling analysis of
a sample of 162 z=4.5 and 14 z=5.7 Lyα emitting galaxies (LAEs)
in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 µm
from the Spitzer Lyα Survey, along with Hubble Space Telescope
NICMOS and WFC3 imaging at 1.1 and 1.6 µm for a subset of the LAEs.
This represents one of the largest samples of high-redshift LAEs
imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs
and 9/14 (64%) of the z=5.7 LAEs are detected at ≥3σ in at least
one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of
stellar mass, from 5x108-1011 M☉. One-third of the IRAC-detected
LAEs have older stellar population ages of 100 Myr-1 Gyr, while the
remainder have ages <100 Myr. A stacking analysis of IRAC-undetected
LAEs shows this population to be primarily low mass (8-20x108 M☉)
and young (64-570 Myr). We find a correlation between stellar mass and
the dust-corrected ultraviolet-based star formation rate (SFR) similar
to that at lower redshifts, in that higher mass galaxies exhibit
higher SFRs. However, the z=4.5 LAE correlation is elevated 4-5 times
in SFR compared to continuum-selected galaxies at similar redshifts.
The exception is the most massive LAEs which have SFRs similar to
galaxies at lower redshifts suggesting that they may represent a
different population of galaxies than the traditional lower-mass LAEs,
perhaps with a different mechanism promoting Lyα photon escape.
Description:
The LAEs targeted by the Spitzer survey were discovered by the Large
Area Lyman Alpha (LALA) Survey (Rhoads et al. 2000ApJ...545L..85R 2000ApJ...545L..85R),
which includes the Bootes field and has accompanying deep broadband
imaging in B, V, R, I, and z' bands taken with the MOSAIC camera on
the 4 m Mayall telescope at the Kitt Peak National Observatory. To
select the z=4.5 and 5.7 LAE candidates the following criteria were
used: (1) a secure detection (>5σ) in the narrowband filter;
(2) a strong narrowband excess, i.e., the flux density in the
narrowband should exceed that in the broadband at the 4σ level,
this is done by requiring a narrowband-broadband color ←0.75 mag;
and (3) no flux at wavelengths shorter than the expected Lyman break.
The last condition implies that at z=4.5, sources are undetected in
the B-band, while for z=5.7 sources, they are undetected in both the
B-band and V-band.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 132 61 LAE z∼4.5 Sample - Flux Measurements
table3.dat 132 14 LAE z∼5.7 Sample - Flux Measurements
table4.dat 78 30 z=4.5 IRAC Detected LAEs - Model SED Fitting
Results
table5.dat 78 15 z=4.5 HST NIR Detected LAEs with IRAC Upper
Limits - Model SED Fitting Results
table6.dat 78 9 z=5.7 IRAC Detected LAEs - Model SED Fitting
Results
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See also:
J/ApJ/671/1227 : Lyα galaxies at z∼4.5 (Dawson+, 2007)
J/ApJS/172/523 : COSMOS field Lyα emitters at z∼5.7 (Murayama+, 2007)
J/ApJ/706/762 : LAEs at z∼4.5 in the LALA Cetus field (Wang+, 2009)
J/ApJ/810/107 : Lyman break galaxies and LAEs HST photometry (Mostardi+, 2015)
J/ApJ/817/119 : Spitzer/IRAC variability survey of Bootes field
(Kozlowski+, 2016)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [3/231] Source identifier
4- 5 A2 --- n_ID [c nc] Note on ID (G1)
7- 15 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
17- 25 F9.6 deg DEdeg Declination in decimal degrees (J2000)
27- 32 F6.4 uJy FNB Narrow Band flux density (1)
34- 39 F6.4 uJy e_FNB Uncertainty in FNB
41- 46 F6.3 uJy FR MOSAIC R band flux density
48- 52 F5.3 uJy e_FR Uncertainty in FR
54- 59 F6.3 uJy FI MOSAIC I band flux density
61- 65 F5.3 uJy e_FI Uncertainty in FI
67- 72 F6.3 uJy Fz MOSAIC z' band flux density
74- 79 F6.4 uJy e_Fz Uncertainty in Fz
81- 86 F6.4 uJy F110W ? HST/WFC3 F110W band flux density
88- 92 F5.3 uJy e_F110W ? Uncertainty in F110W
94- 99 F6.3 uJy F160W ? HST/WFC3 F160W band flux density
101-105 F5.3 uJy e_F160W ? Uncertainty in F160W
107-112 F6.3 uJy F3.6 ? Spitzer/IRAC 3.6µm flux density
114-119 F6.4 uJy e_F3.6 ? Uncertainty in F3.6
121-126 F6.3 uJy F4.5 ? Spitzer/IRAC 4.5µm flux density
128-132 F5.3 uJy e_F4.5 ? Uncertainty in F4.5
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Note (1): The observed narrow-band for the z=5.7 sources is at 815 or 823 nm.
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Byte-by-byte Description of file: table4.dat table5.dat table6.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [3/231] Source identifier
4- 5 A2 --- n_ID [c nc] Note on ID (G1)
7- 10 F4.1 --- chi2 Reduced χ2 of best-fitting model
12- 18 F7.2 10+8Msun Mass Best-fit mass
20- 26 F7.2 10+8Msun b_Mass [] Mass 68% confidence interval, lower value
28- 33 F6.1 10+8Msun B_Mass [] Mass 68% confidence interval, upper value
35- 38 I4 Myr Age Best-fit age
40- 43 I4 Myr b_Age Age 68% confidence interval, lower value
45- 48 I4 Myr B_Age [] Age 68% confidence interval, upper value
50- 53 F4.2 mag E(B-V) Best-fit dust extinction
55- 58 F4.2 mag b_E(B-V) [] Extinction 68% confidence interval, lower
value
60- 63 F4.2 mag B_E(B-V) [] Extinction 68% confidence interval, upper
value
65- 68 F4.2 [Sun] Z Best-fit metallicity
70- 73 F4.2 [Sun] b_Z Metallicity 68% confidence interval, lower
value
75- 78 F4.2 [Sun] B_Z [] Metallicity 68% confidence interval, upper
value
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Global notes:
Note (G1): Note as follows:
c = LAEs that have been spectroscopically confirmed;
nc = LAEs that have a photometric redshift based on narrow-band imaging, and
have not been targeted spectroscopically.
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History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 11-Oct-2017