J/A+A/628/A13 PSZ2 cluster candidates. I. (Streblyanska+, 2019)
Optical validation and characterization of Planck PSZ2 sources at the Canary
Islands observatories. I. First year of LP15 observations.
Streblyanska A., Aguado-Barahona A., Ferragamo A., Barrena R.,
Rubino-Martin J.A., Tramonte D., Genova-Santos R.T., Lietzen H.
<Astron. Astrophys., 628, A13 (2019)>
=2019A&A...628A..13S 2019A&A...628A..13S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts
Keywords: large-scale structure of Universe - galaxies: clusters: general -
galaxies: photometry - catalogs
Abstract:
Aims. The second catalogue of Planck Sunyaev-Zeldovich (SZ) sources,
hereafter PSZ2, is the largest sample of galaxy clusters selected
through their SZ signature in the full sky. At the time of
publication, 21% of these objects had no known counterpart at other
wavelengths. Using telescopes at the Canary Island observatories, we
conducted the long-term observational programme 128-MULTIPLE-16/15B
(hereafter LP15), a large and complete optical follow-up campaign of
all the unidentified PSZ2 sources in the northern sky, with
declinations above -15° and no correspondence in the first Planck
catalogue PSZ1. The main aim of LP15 is to validate all those SZ
cluster candidates, and to contribute to the characterization of the
actual purity and completeness of full Planck SZ sample. In this
paper, we describe the full programme and present the results of the
first year of observations. Methods. The LP15 programme was awarded 44
observing nights, spread over two years in three telescopes at the
Roque de los Muchachos Observatory. The full LP15 sample comprises 190
previously unidentified PSZ2 sources. For each target, we performed
deep optical imaging and spectroscopy. Our validation procedure
combined this optical information with SZ emission as traced by the
publicly available Planck Compton y-maps. The final classification of
the new galaxy clusters as optical counterparts of the SZ signal is
established according to several quantitative criteria based on the
redshift, velocity dispersion, and richness of the clusters. Results.
This paper presents the detailed study of 106 objects out of the LP15
sample, corresponding to all the observations carried out during the
first year of the programme. We confirmed the optical counterpart for
41 new PSZ2 sources, 31 of them being validated using also velocity
dispersion based on our spectroscopic information. This is the largest
dataset of newly confirmed PSZ2 sources without any previous optical
information. All the confirmed counterparts are rich structures (i.e.
they show high velocity dispersion), and are well aligned with the
nominal Planck coordinates (i.e. ∼70% of them are located at less than
3' distance). In total, 65 SZ sources are classified as unconfirmed,
57 of them being due to the absence of an optical over-density, and
eight of them due to a weak association with the observed SZ
decrement. Most of the sources with no optical counterpart are located
at low galactic latitudes and present strong galactic cirrus in the
optical images, the dust contamination being the most probable
explanation for their inclusion in the PSZ2 catalogue.
Description:
This paper opens a series of publications dedicated to the scientific
exploitation of the results obtained with the LP15 programme, a large,
systematic, and uniform follow-up campaign of all the unconfirmed and
new Planck PSZ2 sources in the northern hemisphere (i.e. having
declinations Dec>-15° and not being included in the PSZ1
catalogue). With this definition, our LP15 sample contains 190 objects
(out of the 350 unconfirmed objects in the full sky with no
correspondence in the PSZ1 catalogue).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 144 110 *107 PSZ2 sources discussed in this paper
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Note on tablea1.dat: We show information for 106 LP15 cluster candidates plus
one cluster from Streblyanska et al. (2018A&A...617A..71S 2018A&A...617A..71S) with updated
redshift information.
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See also:
J/A+A/594/A27 : Planck Sunyaev-Zeldovich sources (PSZ2) (Planck+, 2016)
J/A+A/631/A148 : PSZ2 cluster candidates. II. (Aguado-Barahona+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Official identification number
5 A1 --- --- [-]
6 A1 --- m_ID [AB] Multiplicity index on ID for
multiple counterparts
8- 12 A5 --- n_ID Notes on ID (1)
14- 31 A18 --- PSZ2 PSZ2 designation, PSZ2 GLLL.ll+BB.bb
33- 37 F5.2 --- S/N ? SZ signal-to-noise ratio
39- 42 F4.2 --- Qual ? Neural network quality flag (best = 0)
44- 45 I2 h RAh ? BGC Right ascension (J2000)
47- 48 I2 min RAm ? BGC Right ascension (J2000)
50- 55 F6.3 s RAs ? BGC Right ascension (J2000)
56 A1 --- DE- BGC Declination sign (J2000)
57- 58 I2 deg DEd ? BGC Declination (J2000)
60- 61 I2 arcmin DEm ? BGC Declination (J2000)
63- 67 F5.2 arcsec DEs ? BGC Declination (J2000)
69- 72 F4.2 arcmin Dist ? Distance between Planck and the optical
center reported in this work
74- 77 F4.2 --- zph ? Photometric redshift of the cluster
78 A1 --- n_zph [bc] Note on zph (1)
80- 84 F5.3 --- zsp ? Mean spectroscopic redshift of the cluster
87- 92 F6.3 --- zsp2 ? BCG spectroscopic redshift
(-1 if absence of the apparent BCG)
94- 95 I2 --- nsp ? Number of galaxies with spectroscopic
measurement
97-101 F5.1 --- R ? Optical richness of the cluster
(-1 when not could be estimated)
102 A1 --- n_R [ag] Note on R (1)
104-108 F5.2 --- s_R []? Significance of optical richness of the
cluster (-1 when not could be estimated)
110-111 A2 --- Flag Flag (2)
113-144 A32 --- Notes Notes
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Note (1): Notes as follows:
a = Richness calculated using SDSS DR12 data data
(no LP15 photometric data available).
b = Photometric redshift obtained from SDSS DR12 data
Streblyanska et al. (2018A&A...617A..71S 2018A&A...617A..71S).
c = SZ targets identified with the ID followed by an A or B label indicate the
presence of multiple counterparts.
d = Confirmed in Streblyanska et al. (2018A&A...617A..71S 2018A&A...617A..71S).
New LP15 photometric or spectroscopic data are available.
e = Classified as "potentially associated" in Streblyanska et al.
(2018A&A...617A..71S 2018A&A...617A..71S).
f = An extra source from Streblyanska et al. (2018A&A...617A..71S 2018A&A...617A..71S) with
new spectroscopic information, not included in LP15 sample.
g = Richness calculated without local background subtraction due to the small
FOV or poor observing conditions.
Note (2): Flag as follows:
1 = confirmed new PSZ2 source, spectroscopic confirmation
2 = confirmed new PSZ2 source, photometric confirmation
3 = weak associations with the corresponding SZ source
ND = SZ candidates without a galaxy overdensity in the optical images
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History:
From electronic version of the journal
References:
Aguado-Barahona et al., Paper II 2019A&A...631A.148A 2019A&A...631A.148A, Cat. J/A+A/631/A148
(End) Patricia Vannier [CDS] 19-Feb-2020