J/ApJ/736/18 Lyman-continuum emission at z∼3 in SSA22 field (Nestor+, 2011)
Narrowband imaging of escaping Lyman-continuum emission in the SSA22 field.
Nestor D.B., Shapley A.E., Steidel C.C., Siana B.
<Astrophys. J., 736, 18 (2011)>
=2011ApJ...736...18N 2011ApJ...736...18N
ADC_Keywords: Galaxies, optical ; Redshifts ; Surveys ; Photometry ; Ultraviolet
Keywords: cosmology: observations - diffuse radiation -
galaxies: high-redshift - intergalactic medium
Abstract:
We present the results of an ultradeep, narrowband imaging survey for
Lyman-continuum (LyC) emission at z∼3 in the SSA22a field. We employ a
custom narrowband filter centered at λ=3640Å (NB3640), which
probes the LyC region for galaxies at z≥3.06. We also analyze new and
archival NB4980 imaging tuned to the wavelength of the Lyα
emission line at z=3.09, and archival broadband B, V, and R images of
the non-ionizing UV continuum. Our NB3640 images contain 26 z≥3.06
Lyman break galaxies (LBGs) as well as a set of 130 Lyα emitters
(LAEs), identified by their excess NB4980 flux relative to the BV
continuum. Six LBGs and 28 LAEs are detected in the NB3640 image. LBGs
appear to span a range of NB3640-R colors, while LAEs appear bimodal
in their NB3640-R properties. We estimate average UV-to-LyC flux
density ratios.
Description:
The NB3640 imaging data were collected,using the blue side of the Keck
Low Resolution Imaging Spectrometer (LRIS), on 2005 August 6-7 and
2008 June 2-4 (UT). During the 2005 August run, the red side of LRIS
was simultaneously used to collect NB4980 data. The pointing center of
the LRIS imaging field was RA(J2000)=22:17:28.8, DE(J2000)=+00:14:36,
and the area of the final trimmed stacks is 5.5'x7.6'. Narrowband
images were calibrated onto the AB system and were also corrected for
a Galactic extinction of E(B-V)=0.08.
We augmented the LRIS data set with both narrowband and broadband
archival imaging data taken with Suprime-Cam on the Subaru Telescope.
Broadband B- and V-band images were obtained on 2003 September 21 (UT;
PI: Hu). We constructed a BV continuum image by first smoothing the
V-band image so that the B and V image point-spread functions (PSFs)
were matched, and then scaling the PSF-matched images to the same
zeropoint. We then executed: BV=0.44B+0.56V, with the weights
determined by the relative wavelengths of the broadband and NB4980
filters.
Finally, for detailed rest-frame UV (non-ionizing) continuum
morphologies of our SSA22a targets, we assembled archival Hubble Space
Telescope (HST) Advanced Camera for Surveys (ACS) imaging of the
field, taken with the F814W filter. See section 2 for further
explanations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 79 6 Photometry for LBGs (Lyman Break galaxies)
with NB3640 Detections
table5.dat 85 28 Photometry for LAEs (Lyman Alpha Eimitters)
with NB3640 Detections
table9.dat 67 20 Photometry for LBGs without NB3640 Detections
table10.dat 72 102 Photometry for LAEs without NB3640 Detections
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/MNRAS/401/1521 : Stellar masses of LBGs at z∼3 (Magdis+, 2010)
J/A+A/498/13 : Lyman-α emitters from redshifts z∼2-3 (Nilsson+, 2009)
J/ApJ/705/639 : Sizes of Lyman alpha emitters at z=3.1 (Bond+, 2009)
J/ApJ/592/728 : Lyman break galaxies at redshift z∼3 (Steidel+, 2003)
J/PASJ/53/653 : SSA 22 field NIR imaging (Tamura+, 2001)
J/ApJ/519/1 : Lyman-break galaxies at z ≳ 4 (Steidel+, 1999)
Byte-by-byte Description of file: table[49].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- ID Source identification
10- 11 I2 h RAh [22] Hour of right ascension (J2000)
13- 14 I2 min RAm [17] Minute of right ascension (J2000)
16- 20 F5.2 s RAs Second of right ascension (J2000)
22 A1 --- DE- [+] Sign of declination (J2000)
23 I1 deg DEd [0] Degree of declination (J2000)
25- 26 I2 arcmin DEm Arcminute of declination (J2000)
28- 31 F4.1 arcsec DEs Arcsecond of declination (J2000)
33- 38 F6.4 --- zem [3.07/3.30]? Lyα emission redshift
40- 45 F6.4 --- zabs [3.06/3.29]? Interstellar absorption redshift
47- 51 F5.2 mag Rmag [23.49/25.2] R-band AB magnitude
53- 57 F5.2 mag [3640] ? Narrow-band 3640 magnitude (only for table 4)
59- 61 F3.1 arcsec delR ? Spatial offset between the centroids of
R-band and NB3640 emission (only for table 4)
63 A1 --- l_FUV/Fo Limit flag on FUV/Fo
64- 67 F4.1 --- FUV/Fo [1.4/29.2] Observed ratio in non-ionizing UV
and LyC emission (G1)
69- 71 F3.1 --- e_FUV/Fo ? FUV/Fo uncertainty
73- 75 F3.1 --- FUV/Fc ? Ratio of non-ionizing UV continuum and LyC
emission (only for table 4) (G2)
77- 79 F3.1 --- e_FUV/Fc ? FUV/Fc uncertainty
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Byte-by-byte Description of file: table5.dat table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Source number (003-118 for table 5; 001-130 for
table 10)
4 A1 --- f_Seq [c-i] Individual notes (1)
6- 7 I2 h RAh [22] Hour of right ascension (J2000)
9- 10 I2 min RAm [17] Minute of right ascension (J2000)
12- 16 F5.2 s RAs Second of right ascension (J2000)
18 A1 --- DE- [+] Sign of declination (J2000)
19 I1 deg DEd [0] Degree of declination (J2000)
21- 22 I2 arcmin DEm Arcminute of declination (J2000)
24- 27 F4.1 arcsec DEs Arcsecond of declination (J2000)
29- 33 F5.2 mag [4980] [23/26.49] Keck/LRIS NB4980 magnitude
35 A1 --- l_BV-4980 Limit flag on BV-4980
36- 39 F4.2 mag BV-4980 [0.71/2.68] BV-NB4980 color index
41 A1 --- l_EW0 Limit flag on EW0
42- 44 I3 0.1nm EW0 [19/400] Lyα rest equivalent width
estimated from BV-NB4980 color index
46 A1 --- l_Rmag Limit flag on Rmag
47- 51 F5.2 mag Rmag [23.92/27] R-band AB magnitude
53- 57 F5.2 mag [3640] ? Narrow-band 3640 magnitude (only for table 5)
59- 61 F3.1 arcsec delR ? Spatial offset between the centroids of
R and NB3640 emission (only for table 5)
62 A1 --- f_delR [e] e: offset determined from the centroid of
BV detection
64- 66 F3.1 arcsec delLya ? Spatial offset between the centroids of
Lyα and NB3640 emission (only for table 5)
68 A1 --- l_FUV/Fo Limit flag on FUV/Fo
69- 72 F4.1 --- FUV/Fo [0.5/22.4]? Observed ratio in non-ionizing UV
and LyC emission (G1)
74- 76 F3.1 --- e_FUV/Fo ? FUV/Fo uncertainty
78 A1 --- l_FUV/Fc Limit flag on FUV/Fc
79- 81 F3.1 --- FUV/Fc ? Ratio of non-ionizing UV continuum and LyC
emission (G2)
83- 85 F3.1 --- e_FUV/Fc ? FUV/Fc uncertainty
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Note (1): Flag as follows:
c = LBG D3 (<SAS-LBG SSA22a-D3> in Simbad), zem=3.086.
d = LBG C4 (<SAS-LBG SSA22a-C4> in Simbad), zem=3.076.
e = LBG MD23 (<SAS-LBG SSA22a-MD23> in Simbad), zem=3.092.
f = LBG C28 (<SAS-LBG SSA22a-C28> in Simbad), zem=3.076.
g = LBG candidate C9 (<SAS-LBG SSA22a-C9> in Simbad).
h = LBG M28 (<SAS-LBG SSA22a-M28> in Simbad), zem=3.094.
i = LBG candidate M13 (<SAS-LBG SSA22a-M13> in Simbad).
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Global notes:
Note (G1): Observed ratio in non-ionizing UV and LyC emission; inferred
from the NB3640-R color (for tables 4 and 5). This value has not been
corrected for either contamination by foreground sources or IGM
absorption.
Note (G2): Corrected for both foreground contamination and IGM absorption.
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Nomenclature notes:
In tables 4 and 9, IDs come from Steidel et al., 2003, Cat. J/ApJ/592/728,
<SAS-LBG SSA22a-AANN> or <SAS-LBG SSA22a-aug96AANN> in Simbad.
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 06-Dec-2012