J/MNRAS/466/1242 CALYMHA survey. I. (Sobral+, 2017)
The CALYMHA survey: Lyα luminosity function and global escape fraction
of Lyα photons at z = 2.23.
Sobral D., Matthee J., Best P., Stroe A., Rottgering H., Oteo I., Smail I.,
Morabito L., Paulino-afonso A.
<Mon. Not. R. Astron. Soc., 466, 1242-1258 (2017)>
=2017MNRAS.466.1242S 2017MNRAS.466.1242S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Equivalent widths ; Photometry
Keywords: galaxies: evolution - galaxies: haloes - galaxies: high-redshift -
galaxies: luminosity function, mass function - galaxies: statistics -
cosmology: observations
Abstract:
We present the CAlibrating LYMan-α with Hα (CALYMHA) pilot
survey and new results on Lyman α (Lyα) selected galaxies
at z∼2. We use a custom-built Lyα narrow-band filter at the
Isaac Newton Telescope, designed to provide a matched volume coverage
to the z=2.23Hα HiZELS survey. Here, we present the first
results for the COSMOS and UDS fields. Our survey currently reaches a
3σ line flux limit of ∼4x10-17erg/s/cm2, and a Lyα
luminosity limit of ∼1042.3erg/s. We find 188 Lyα emitters
over 7.3x105Mpc3, but also find significant numbers of other
line-emitting sources corresponding to HeII, CIII] and CIV emission
lines. These sources are important contaminants, and we carefully
remove them, unlike most previous studies. We find that the Lyα
luminosity function at z=2.23 is very well described by a Schechter
function up to LLyα~=1043erg/s^ with
L*=1042.59(1042.75-1042.01^)erg/s,
φ*=10-3.09(10-3.43-102.95)Mpc-3^ and α=-1.75±0.25.
Above LLyα~=1043erg/s, the Lyα luminosity function
becomes power-law like, driven by X-ray AGN. We find that
Lyα-selected emitters have a high escape fraction of 37±7 per
cent, anticorrelated with Lyα luminosity and correlated with
Lyα equivalent width. Lyα emitters have ubiquitous large
(~=40kpc) Lyα haloes, ∼2 times larger than their Hα
extents. By directly comparing our Lyα and Hα luminosity
functions, we find that the global/overall escape fraction of
Lyα photons (within a 13kpc radius) from the full population of
star-forming galaxies is 5.1±0.2 per cent at the peak of the star
formation history. An extra 3.3±0.3 per cent of Lyα photons
likely still escape, but at larger radii.
Description:
Observations were obtained with a custom-built narrow-band filter
(NB392) for the Isaac Newton Telescope's Wide Field Camera (INT/WFC).
The NB392 filter (λc=3918Å, {DELTA}λ=52Å) was
designed by us such that the transmission of the redshifted Lyα
line matches that of the redshifted Hα line in the NBK filter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 149 440 Catalogue of 440 candidate line emitters
selected in COSMOS and UDS
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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- 15 A15 --- Name Name (CALYMHA-S16-NNN)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 28 F6.3 s RAs Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
31- 32 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
37- 41 F5.2 arcsec DEs Declination (J2000)
43- 49 F7.4 mag NB392 INT/WFC NB392 (3918Å) magnitude (AB)
51- 57 F7.4 mag umag CFHT u magnitude (AB)
61- 81 E21.18 mW/m2 Flux Flux in NB filter
83-104 E22.18 [mW/m2] logFlux log of flux in NB filter
107-127 E21.18 0.1nm EWobs Observed equivalent width
130-149 E20.18 --- SIGMA3 Significance cut
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Aug-2019