J/ApJS/237/31 CLAMATO DR1: 3D Lyα forest tomography (Lee+, 2018)
First data release of the COSMOS Lyα Mapping and Tomography Observations:
3D Lyα forest tomography at 2.05<z<2.55.
Lee K.-G., Krolewski A., White M., Schlegel D., Nugent P.E., Hennawi J.F.,
Muller T., Pan R., Prochaska J.X., Font-Ribera A., Suzuki N.,
Glazebrook K., Kacprzak G.G., Kartaltepe J.S., Koekemoer A.M., Le Fevre O.,
Lemaux B.C., Maier C., Nanayakkara T., Rich R.M., Sanders D.B., Salvato M.,
Tasca L., Tran K.-V.H.
<Astrophys. J. Suppl. Ser., 237, 31 (2018)>
=2018ApJS..237...31L 2018ApJS..237...31L
ADC_Keywords: Intergalactic medium; Galaxies, spectra; QSOs; Redshifts; Optical
Keywords: intergalactic medium ; large-scale structure of universe ;
quasars: absorption lines ; surveys ; techniques: spectroscopic
Abstract:
Faint star-forming galaxies at z∼2-3 can be used as alternative
background sources to probe the Lyα forest in addition to
quasars, yielding high sightline densities that enable 3D tomographic
reconstruction of the foreground absorption field. Here, we present
the first data release from the COSMOS Lyα Mapping And
Tomography Observations (CLAMATO) Survey, which was conducted with the
LRIS spectrograph on the Keck I telescope. Over an observational
footprint of 0.157deg2 within the COSMOS field, we used 240 galaxies
and quasars at 2.17<z<3.00, with a mean comoving transverse separation
of 2.37h-1Mpc, as background sources probing the foreground
Lyα forest absorption at 2.05<z<2.55. The Lyα forest data
was then used to create a Wiener-filtered tomographic reconstruction
over a comoving volume of 3.15x105h-3Mpc3 with an effective
smoothing scale of 2.5h-1Mpc. In addition to traditional figures,
this map is also presented as a virtual-reality visualization and
manipulable interactive figure. We see large overdensities and
underdensities that visually agree with the distribution of coeval
galaxies from spectroscopic redshift surveys in the same field,
including overdensities associated with several recently discovered
galaxy protoclusters in the volume. Quantitatively, the map
signal-to-noise is S/Nwiener∼3.4 over a 3h-1Mpc top-hat kernel
based on the variances estimated from the Wiener filter. This data
release includes the redshift catalog, reduced spectra, extracted
Lyα forest pixel data, and reconstructed tomographic map of the
absorption.
Description:
The COSMOS Lyα Mapping And Tomography Observations (CLAMATO)
observations were carried out using the LRIS spectrograph on the KeckI
telescope at Maunakea, Hawai'i. The observations described in these
papers were carried out in the spring semesters of 2014-2017 via a
total time allocation of 15.5 nights.
For CLAMATO, we focused on the LRIS blue channel, which covers the
3700Å<λ<4400Å wavelength range corresponding to
rest-frame Lyα at 2.1≲zα≲2.6, our redshifts of
interest (spectral resolution of R∼1100).
From the 23 unique slitmasks observed in the 2014-2017 CLAMATO
campaign, we successfully reduced and extracted 437 spectra from the
blue channel.
Out of the 437 reduced spectra, 289 spectra had confident
identifications (≥3 confidence rating), of which 277 were at
redshifts z>2. These high-redshift sources can be further classified
into 262 galaxies (95%) and 15 broad-line quasars (5%).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 77 437 CLAMATO Data Release 1 source catalog
spec_v0/* . 465 Individual reduced LRIS-Blue spectra in FITS format
specv0red/* . 378 Individual reduced LRIS-Red spectra in FITS format
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See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)
J/A+A/530/A50 : Principal Component Analysis of QSO UV spectra (Paris+, 2011)
J/A+A/559/A85 : 1D Lya forest power spectrum (Palanque-Delabrouille+, 2013)
J/ApJS/206/8 : COSMOS/UltraVISTA Ks-selected catalogs v4.1 (Muzzin+, 2013)
J/ApJ/828/21 : ZFIRE v1.0 data release (Nanayakkara+, 2016)
J/ApJ/830/51 : FourStar galaxy evolution survey (ZFOURGE) (Straatman+, 2016)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [762/34724] Sequential numeric identifier
7- 8 I2 h RAh [9/10] Hour of Right Ascension (J2000) (1)
10- 11 I2 min RAm Minute of Right Ascension (J2000) (1)
13- 18 F6.3 s RAs Second of Right Ascension (J2000) (1)
20- 20 A1 --- DE- [+] Sign of the Declination (J2000)(1)
21- 22 I2 deg DEd [1/2] Degree of Declination (J2000) (1)
24- 25 I2 arcmin DEm [8/45] Arcminute of Declination (J2000) (1)
27- 31 F5.2 arcsec DEs Arcsecond of Declination (J2000) (1)
33- 37 F5.2 mag gmag [20.1/25.3] g band AB magnitude (1)
39- 42 F4.2 --- zphot [0.06/3.1] Photometric redshift estimate
44- 48 F5.3 --- zspec [0.04/3.5]?=0 Spectroscopic redshift
50- 50 I1 --- Conf [0/4] Redshift confidence grade (4: very secure) (2)
52- 54 A3 --- Type Type (421 "GAL"; 16 "QSO")
56- 60 I5 s Texp [7200/41400] Exposure time, seconds
62- 62 A1 --- Tomo [NY] Usage in Lyα forest tomographic
reconstruction
64- 67 F4.1 --- SN1 [0.4/36]? Median per-pixel spectral
continuum-to-noise ratio within 2.05<zα<2.15
Lyα forest
69- 72 F4.1 --- SN2 [0.4/42.2]? Median per-pixel spectral
continuum-to-noise ratio within 2.15<zα<2.35
Lyα forest
74- 77 F4.1 --- SN3 [0.4/49.2]? Median per-pixel spectral
continuum-to-noise ratio within 2.35<zα<2.55
Lyα forest
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Note (1): Source positions and magnitudes from Capak+ (2007, II/284).
Note (2): Redshift confidence grade similar to that described in Lilly+
(2007, J/ApJS/172/70) but without fractional grades
(4=very secure, 3=secure, 2=probable or 1=insecure redshift;
0=unidentified spectrum).
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History:
From electronic version of the journal
References:
Horowitz et al. DR2. 2022ApJS..263...27H 2022ApJS..263...27H Cat. J/ApJS/263/27
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Oct-2018