J/MNRAS/483/1354 Interplanetary scintillation studies with MWA (Sadler+, 2019)
Interplanetary scintillation studies with the Murchison Wide-field Array - IV.
The hosts of sub-arcsecond compact sources at low radio frequencies.
Sadler E.M., Chhetri R., Morgan J., Mahony E.K., Jarrett T.H., Tingay S.
<Mon. Not. R. Astron. Soc., 483, 1354-1373 (2019)>
=2019MNRAS.483.1354S 2019MNRAS.483.1354S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Radio continuum ; QSOs ; Galaxies
Keywords: galaxies: active - radio continuum: galaxies - quasars: general
Abstract:
Around 10 per cent of bright low-frequency radio sources observed with
the Murchison Wide-field Array (MWA) show strong interplanetary
scintillation (IPS) on time-scales of a few seconds, implying that
almost all their low-frequency radio emission comes from a compact
component less than 0.5arcsec in angular size. Most of these objects
are compact steep-spectrum or MHz-peaked spectrum radio sources. We
have used mid-infrared data from the Wide-field Infrared Survey
Explorer (WISE) catalogue to search for the host galaxies of 65
strongly scintillating MWA sources and compare their properties with
those of the overall population of bright low-frequency radio sources.
We identified WISE mid-infrared counterparts for 91 per cent of the
bright sources in a single 900deg2 MWA field, and found that the
hosts of the strongly scintillating sources were typically at least
1mag fainter in the WISE W1 (3.4µm) band than the hosts of weakly
scintillating MWA sources of similar radio flux density. This
difference arises mainly because the strongly scintillating sources
are more distant. We estimate that strongly scintillating MWA sources
have a median redshift of z∼1.5, and that at least 30 per cent of them
are likely to lie at z>2. The recently developed wide-field IPS
technique therefore has the potential to provide a powerful new tool
for identifying high-redshift radio galaxies without the need for
radio spectral-index selection.
Description:
The data samples analysed in this paper are drawn from the 900deg2
MWA field observed by Chhetri et al. (2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937). To identify the host galaxies of these sources, we
used the all-sky mid-IR Wide-field Infrared Survey Explorer (WISE)
allWISE catalogue (Wright et al. 2010AJ....140.1868W 2010AJ....140.1868W; Cutri et al.
2013wise.rept....1C, Cat. II/328). This is currently the deepest
large-area photometric catalogue available, and most powerful radio
active galactic nuclei (AGNs) out to redshift z∼1.5 are expected to
have a counterpart in the WISE catalogue (Gurkan, Hardcastle & Jarvis
2014MNRAS.438.1149G 2014MNRAS.438.1149G, Cat. J/MNRAS/438/1149; Glowacki et al.
2017arXiv170908634G 2017arXiv170908634G).
To derive the most accurate radio positions for WISE cross-matching,
we matched the MWA GLEAM sources with objects in the higher resolution
1.4GHz FIRST (Becker, White & Helfand 1995ApJ...450..559B 1995ApJ...450..559B, Cat.
VIII/92) and NVSS (Condon et al. 1998AJ....115.1693C 1998AJ....115.1693C, Cat. VIII/65)
catalogues. This cross-matching process is reasonably straightforward,
since the MWA sources are bright enough at 162MHz that they should be
easily detectable in the higher frequency surveys even if resolved
into two or more components.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 150 94 The main IPS-FIRST sample of high S/N sources
from the Chhetri et al. (2018MNRAS.474.4937C 2018MNRAS.474.4937C)
IPS sample that lie within the FIRST overlap
area
table4.dat 134 65 Expanded list of strongly scintillating
(NSI≥0.90, NormSNR≥8.0) sources from the
Chhetri et al. (2018MNRAS.474.4937C 2018MNRAS.474.4937C) IPS sample
with no restriction on sky area
table5.dat 130 85 The IPS-MRC-1Jy sample of sources from the
Chhetri et al. (2018MNRAS.474.4937C 2018MNRAS.474.4937C) IPS sample
that also appear in the MRC-1Jy sample
notes.dat 783 25 Individual notes on the sources listed in
Tables 3, 4 and 5
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See also :
J/MNRAS/473/2965 : Interplanetary scintillation at 79 and 158MHz
(Morgan+ 2018)
J/MNRAS/474/4937 : Interplanetary scintillation at 162 and 1400MHz
(Chhetri+ 2018)
II/328 : AllWISE Data Release (Cutri+ 2013)
VIII/92 : The FIRST Survey Catalog (Helfand+ 2015)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- SNRclass Subsample name based on the value of
NormSNR (1)
6- 19 A14 --- Name GLEAM name for the source (JHHMMSS+DDMMSS)
21- 34 A14 --- Oname Alternative name
36- 41 F6.3 Jy S162 162MHz flux density from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
43- 47 F5.3 Jy e_S162 Error on S162
49- 52 F4.1 --- NormSNR Normalized S/N ratio from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
54 A1 --- l_NSI Upper limit on NSI for sources where IPS waw
not detected
56- 59 F4.2 --- NSI Normalized scintillation index
61 I1 --- FIRSTcomp Number of separate FIRST components
associated with the GLEAM source
63- 74 A12 --- Radioclass Radio source classification
76- 77 I2 h RAh Right ascension (J2000) (2)
79- 80 I2 min RAm Right ascension (J2000) (2)
82- 87 F6.3 s RAs Right ascension (J2000) (2)
89 A1 --- DE- Declination sign (J2000) (2)
90- 91 I2 deg DEd Declination (J2000) (2)
93- 94 I2 arcmin DEm Declination (J2000) (2)
96-100 F5.2 arcsec DEs Declination (J2000) (2)
102-120 A19 --- WISE Name of matched WISE source
122-127 F6.3 mag W1mag ? WISE W1 magnitude
129-133 F5.3 mag e_W1mag ? Error on W1mag
135-140 F6.4 --- z ? Optical spectroscopic redshift
142-146 A5 --- r_z Reference for z (G1)
148-149 A2 --- Note1 [AFP ] Additional notes (3)
150 A1 --- Note2 [*] Indivudal notes in notes.dat
--------------------------------------------------------------------------------
Note (1): Subsample name as follows:
HSNR = High S/N sources in the FIRST survey area (NormSNR≥12.5)
ISNR = Strongly scintillating sources with intermediate S/N in the FIRST
overlap area (NSI>0.90, 8.0≤NormSNR≤12.5)
Note (2): Positions used for WISE cross-matching
Note (3): Additional notes as follows:
A = AT20G source (Murphy et al. 2010MNRAS.402.2403M 2010MNRAS.402.2403M,
Cat. J/MNRAS/402/2403)
F = Fermi gamma-ray source (3FGL; Acero et al. 2015ApJS..218...23A 2015ApJS..218...23A,
Cat. J/ApJS/218/23)
P = Peaked-spectrum source (Callingham et al. 2017ApJ...836..174C 2017ApJ...836..174C,
Cat. J/ApJ/836/174)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name GLEAM name for the source (JHHMMSS+DDMMSS)
16- 34 A19 --- Oname Alternative name
36- 41 F6.3 Jy S162 162MHz flux density from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
43- 47 F5.3 Jy e_S162 Error on S162
49- 54 F6.2 --- NormSNR Normalized S/N ratio from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
56- 59 F4.2 --- NSI Normalized scintillation index
61- 62 I2 h RAh Right ascension (J2000) (1)
64- 65 I2 min RAm Right ascension (J2000) (1)
67- 71 F5.2 s RAs Right ascension (J2000) (1)
73 A1 --- DE- Declination sign (J2000) (1)
74- 75 I2 deg DEd Declination (J2000) (1)
77- 78 I2 arcmin DEm Declination (J2000) (1)
80- 83 F4.1 arcsec DEs Declination (J2000) (1)
85-103 A19 --- WISE Name of matched WISE source
105-110 F6.3 mag W1mag ? WISE W1 magnitude
112-116 F5.3 mag e_W1mag ? Error on W1mag16
118-123 F6.4 --- z ? Optical spectroscopic redshift
125-129 A5 --- r_z Reference for z (G1)
131-133 A3 --- Note1 [AFP35 ] Additional notes (2)
134 A1 --- Note2 [*] Individual notes in notes.dat
--------------------------------------------------------------------------------
Note (1): Positions from the NRAO VLA Sky Survey (NVSS, Condon et al.
1998AJ....115.1693C 1998AJ....115.1693C, Cat. VIII/65)
Note (2): Additional notes as follows:
A = AT20G source (Murphy et al. 2010MNRAS.402.2403M 2010MNRAS.402.2403M,
Cat. J/MNRAS/402/2403)
F = Fermi gamma-ray source (3FGL; Acero et al. 2015ApJS..218...23A 2015ApJS..218...23A,
Cat. J/ApJS/218/23)
P = Peaked-spectrum source (Callingham et al. 2017ApJ...836..174C 2017ApJ...836..174C,
Cat. J/ApJ/836/174)
3 = Source also included in Table 3
5 = Source also included in Table 5
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name GLEAM name for the source (JHHMMSS+DDMMSS)
16- 27 A12 --- Oname Alternative name
29- 34 F6.3 Jy S162 162MHz flux density from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
36- 40 F5.3 Jy e_S162 Error on S162
42- 46 F5.1 --- NormSNR Normalized S/N ratio from Chhetri et al.
(2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat.
J/MNRAS/474/4937)
48 A1 --- l_NSI Upper limit on NSI for sources where IPS was
not detected
50- 53 F4.2 --- NSI Normalized scintillation index
55- 56 I2 h RAh Right ascension (J2000) (1)
58- 59 I2 min RAm Right ascension (J2000) (1)
61- 65 F5.2 s RAs Right ascension (J2000) (1)
67 A1 --- DE- Declination sign (J2000) (1)
68- 69 I2 deg DEd Declination (J2000) (1)
71- 72 I2 arcmin DEm Declination (J2000) (1)
74- 77 F4.1 arcsec DEs Declination (J2000) (1)
79- 81 A3 --- Type Object type (QSO or galaxy (gal))
83-101 A19 --- WISE Name of matched WISE source
103-108 F6.3 mag W1mag ? WISE W1 magnitude
110-114 F5.3 mag e_W1mag ? Error on W1mag
116-121 F6.4 --- z ? Optical spectroscopic redshift
123-126 A4 --- r_z Reference for z (G1)
128-129 A2 --- Note1 [AFP ] Additional notes (2)
130 A1 --- Note2 [*] Individual notes in notes.dat files
--------------------------------------------------------------------------------
Note (1): Radio positions from the MRC-1Jy catalogue
(McCarthy et al. 1996ApJS..107...19M 1996ApJS..107...19M, Cat. J/ApJS/107/19;
Kapahi et al. 1998ApJS..118..327K 1998ApJS..118..327K)
Note (2): Additional notes as follows:
A = AT20G source (Murphy et al. 2010MNRAS.402.2403M 2010MNRAS.402.2403M,
Cat. J/MNRAS/402/2403)
F = Fermi gamma-ray source (3FGL; Acero et al. 2015ApJS..218...23A 2015ApJS..218...23A,
Cat. J/ApJS/218/23)
P = Peaked-spectrum source (Callingham et al. 2017ApJ...836..174C 2017ApJ...836..174C,
Cat. J/ApJ/836/174)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: notes.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name GLEAM name for the source (JHHMMSS+DDMMSS)
16- 29 A14 --- OName Alternative name
31-783 A753 --- Notes Comments on the source
--------------------------------------------------------------------------------
Global notes:
Note (G1): References as follows:
6dFGS = 6dF Galaxy Survey (Jones et al. 2009MNRAS.399..683J 2009MNRAS.399..683J, Cat. VII/259)
Ba99 = Baker et al. (1999ApJS..122...29B 1999ApJS..122...29B)
Du89 = Dunlop et al. (1989MNRAS.238.1171D 1989MNRAS.238.1171D, Cat. J/MNRAS/238/1171)
Dr03 = Drake et al. (2003AJ....126.2237D 2003AJ....126.2237D, Cat. J/AJ/126/2237)
Ho03 = Hook et al. (2003A&A...399..469H 2003A&A...399..469H, Cat. J/A+A/399/469)
Ka98 = Kapahi et al. (1998ApJS..118..327K 1998ApJS..118..327K)
Mc91 = McCarthy et al. (1991AJ....102..522M 1991AJ....102..522M)
Mc96 = McCarthy et al. (1996ApJS..107...19M 1996ApJS..107...19M, Cat. J/ApJS/107/19)
Os94 = Osmer, Porter & Green (1994ApJ...436..678O 1994ApJ...436..678O)
RC3 = Third Reference Catalogue of Bright Galaxies
(de Vaucouleurs et al. 1991rc3..book.....D 1991rc3..book.....D, Cat. VII/155)
Sc65 = Schmidt (1965ApJ...141....1S 1965ApJ...141....1S, )
SDSS = Sloan Digital Sky Survey DR14 (Abolfathi et al. 2018ApJS..235...42A 2018ApJS..235...42A)
Ti11 = Titov et al. (2011AJ....142..165T 2011AJ....142..165T)
We99 = Wegner et al. (1999MNRAS.305..259W 1999MNRAS.305..259W, Cat. J/MNRAS/305/259)
Wi76 = Wills & Wills (1976ApJS...31..143W 1976ApJS...31..143W)
Wo00 = Wold et al. (2000MNRAS.316..267W 2000MNRAS.316..267W)
Wr83 = Wright, Ables & Allen (1983MNRAS.205..793W 1983MNRAS.205..793W)
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History:
From electronic version of the journal
References:
Norgan et al., Paper I 2018MNRAS.473.2965M 2018MNRAS.473.2965M, Cat. J/MNRAS/473/2965
Chhetri et al., Paper II, 2018MNRAS.474.4937C 2018MNRAS.474.4937C, Cat. J/MNRAS/474/4937
Chhetri et al., Paper III, 2018MNRAS.479.2318C 2018MNRAS.479.2318C
(End) Ana Fiallos [CDS] 12-Jul-2022