J/MNRAS/494/5985 SCUBA-2 overdensities in candidate protoclusters (Cheng+, 2020)
SCUBA-2 overdensities associated with candidate protoclusters selected from
Planck data.
Cheng T., Clements D.L., Greenslade J., Cairns J., Andreani P., Bremer M.,
Conversi L., Cooray A., Dannerbauer H., De Zotti G., Eales S.,
Gonzalez-Nuevo J., Ibar E., Leeuw L., Ma J., Michalowski M.J., Nayyeri H.,
Riechers D.A., Scott D., Temi P., Vaccari M., Valtchanov I., van Kampen E.,
Wang L.
<Mon. Not. R. Astron. Soc., 494, 5985-5991 (2020)>
=2020MNRAS.494.5985C 2020MNRAS.494.5985C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Millimetric/submm sources
Keywords: galaxies: high-redshift - galaxies: starburst -
submillimetre: galaxies
Abstract:
We measure the 850-µm source densities of 46 candidate
protoclusters selected from the Planck high-z catalogue (PHz) and the
Planck Catalogue of Compact Sources (PCCS) that were followed up with
Herschel-SPIRE and SCUBA-2. This paper aims to search for
overdensities of 850-µm sources in order to select the fields that
are most likely to be genuine protoclusters. Of the 46 candidate
protoclusters, 25 have significant overdensities (>5 times the field
counts), 11 have intermediate overdensities (3-5 times the field
counts), and 10 have no overdensity (<3 times the field counts) of
850-µm sources. We find that the enhanced number densities are
unlikely to be the result of sample variance. Compared with the number
counts of another sample selected from Planck's compact source
catalogues, this [PHz + PCCS]-selected sample has a higher fraction of
candidate protoclusters with significant overdensities, though both
samples show overdensities of 850-µm sources above intermediate
level. Based on the estimated star formation rate densities (SFRDs),
we suggest that both samples can efficiently select protoclusters with
starbursting galaxies near the redshift at which the global field SFRD
peaks (2<z<3). Based on the confirmation of overdensities found here,
future follow-up observations on other PHz targets may greatly
increase the number of genuine dusty star-forming galaxy-rich
clusters/protoclusters.
Description:
46 candidate protoclusters were selected and studied in MacKenzie et
al. (2017MNRAS.468.4006M 2017MNRAS.468.4006M, Cat. J/MNRAS/468/4006). They were originally
selected from the PHz and the PCCS catalogues, with colour cuts using
their 857, 545, 353, and 217GHz flux densities in order to remove cold
Galactic cirrus and extragalactic radio sources. According to
MacKenzie et al. (2017MNRAS.468.4006M 2017MNRAS.468.4006M, Cat. J/MNRAS/468/4006), only
sources with an infrared excess, or S545/S857>0.5 and
S353/S545<0.9 in the PHz catalogue, and S857/S545<1.5 and
S217/S353<1 in the PCCS catalogue, were selected, where S is the
flux density.
Among these [PHz + PCCS]-selected sources, 228 were followed up with
Herschel-SPIRE. 15 of these 228 sources were then identified as being
gravitationally enhanced submillimetre sources (GEMS), the so-called
Planck dusty GEMS (Combes et al. 2012A&A...538L...4C 2012A&A...538L...4C; Fu et al.
2012ApJ...753..134F 2012ApJ...753..134F; Canameras et al. 2015A&A...581A.105C 2015A&A...581A.105C). After
excluding the Galactic cirrus sources, the rest show overdensities of
Herschel-SPIRE sources with flux densities peaking at 350 or 500µm
(Planck Collaboration XXVII 2015A&A...582A..30P 2015A&A...582A..30P). These sources are
believed to be either high-z protoclusters or chance line-of-sight
projections.
61 sources were observed with SCUBA-2. 10 of these are GEMS in
Canameras et al. (2015A&A...581A.105C 2015A&A...581A.105C), with peak flux densities of
350-1140mJy at 850µm. 46 are believed to be protoclusters due to
their Herschel-SPIRE overdensities.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 122 47 Cumulative number counts of 46 candidate
protoclusters in M17
catalog.dat 148 527 850 micron source catalogues for the
46 candidate protoclusters
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See also:
J/A+A/596/A100 : Planck high-z source candidates catalog (PHZ)
(Planck+, 2016)
J/A+A/594/A26 : Second Planck Catalogue of Compact Sources (PCCS2)
(Planck+, 2016)
J/MNRAS/465/1789 : SCUBA-2 Cosmology Legacy Survey (Geach+, 2017)
J/MNRAS/468/4006 : Proto-cluster candidate fields (Mackenzie+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Protocluster name
21- 24 F4.1 --- CNC4mJy Cumulative number counts for F>4mJy (1)
26- 30 F5.2 --- e_CNC4mJy Error on CNC4mJy
32- 35 F4.1 --- CNC6mJy Cumulative number counts for F>6mJy (1)
37- 41 F5.2 --- E_CNC6mJy Upper error on CNC6mJy
43- 47 F5.2 --- e_CNC6mJy Lower error on CNC6mJy
49- 53 F5.2 --- CNC8mJy ? Cumulative number counts for F>8mJy (1)
55- 59 F5.2 --- E_CNC8mJy ? Upper error on CNC8mJy
61- 65 F5.2 --- e_CNC8mJy ? Lower error on CNC8mJy
67- 71 F5.2 --- CNC10mJy ? Cumulative number counts for F>10mJy (1)
73- 76 F4.2 --- e_CNC10mJy ? Error on CNC10mJy
78- 82 F5.2 --- CNC12mJy ? Cumulative number counts for F>12mJy (1)
84- 88 F5.3 --- e_CNC12mJy ? Error on CNC12mJy
90- 97 E8.3 --- Pran ? Probability of detecting the observed
number of sources in the candidate
protocluster at 8mJy (2)
99 A1 --- f_Pran [*] Flag on Pran (3)
101- 104 I4 --- Nover ? Number of overdense regions when examining
10000 random regions in the S2CLS/COSMOS
field
106 A1 --- l_Pover Limit flag on Pover
108- 113 F6.4 --- Pover ? Probability of obtaining Nover regions
(Nover/10000)
115- 122 A8 --- Category Category of the source (4)
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Note (1): Cumulative number counts represent the number of sources with flux
densities >4, >6, >8, >10, and >12 mJy respectively. Cumulative number
counts are scaled to the size of each map and are corrected for
variable sensitivity, following Cheng et al. 2019MNRAS.490.3840C 2019MNRAS.490.3840C.
Note (2): Pran is computed by assuming that the sources are randomly distributed
and following a Poisson distribution and by comparing to the field
results in Geach et al. (2017MNRAS.465.1789G 2017MNRAS.465.1789G, Cat. J/MNRAS/465/1789)
Note (3): Flag as follows:
* = The probabilities for PLCKHZG173.9+57.0 are calculated based on the
cumulative number counts at 6mJy, since it does not have any sources
brighter than 8mJy
Note (4): Sources are classified into three categories, where category I means
having no overdensity of SCUBA-2 sources, category II corresponds to
having an intermediate overdensity, and category III is having a
significant overdensity, as discussed in Section 3.
For fields below 80 per cent reliability at 3.5σ, we add an 'R'
label. For fields below 50 per cent completeness, we add a 'C' label
(see Section 2 for details).
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Protocluster name
21- 22 I2 --- Seq [0/31] Source sequential number
within the protocluster
24- 47 E24.19 deg RAdeg Right ascension of peak flux density
of the source (J2000)
49- 73 E25.19 deg DEdeg Declination of peak flux density
of the source (J2000)
75- 98 E24.19 --- SNR Signal-to-noise ratio
100-123 E24.19 mJy Speak Peak, deboosted flux density of the source
at 850um
125-148 E24.19 mJy e_Speak Deboosted flux density error at 850um
(A 5% calibration error is also included)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 05-Jun-2023