J/ApJS/262/51 Swift X-ray obs. of 31 SMS4 QSOs & radio gal. (Maselli+, 2022)
A Swift X-ray view of the SMS4 sample-X-ray properties of 31 quasars and radio
galaxies.
Maselli A., Forman W.R., Jones C., Kraft R.P., Perri M.
<Astrophys. J. Suppl. Ser., 262, 51 (2022)>
=2022ApJS..262...51M 2022ApJS..262...51M
ADC_Keywords: Galaxies, radio; QSOs; X-ray sources; Cross identifications;
Photometry, infrared; Optical
Keywords: Active galaxies ; Extragalactic radio sources ; X-ray astronomy
Abstract:
We present Neil Gehrels Swift Observatory (hereafter Swift)
observations of 31 sources from the SMS4 catalog, a sample of
137 bright radio sources originally designed to extend the
well-studied 3CRR radio sample to the Southern Hemisphere. All these
sources had no Chandra or XMM-Newton observations: 24 of these were
observed with Swift through a dedicated proposal in 2015, and data for
the remaining seven were retrieved from the Swift archive. The
reduction and analysis of data collected by the Swift X-ray Telescope
(XRT) led to 20 detections in the 0.3-10 keV band. We provide details
of the X-ray emission in this band for these 20 detections, as well as
upper limits for the remaining 11 SMS4 sources. When statistics
allowed, we investigated the extent of the X-ray emission and the
hardness ratio, and we carried out a spectral analysis. We matched the
20 X-ray-detected sources with infrared (AllWISE, CatWISE2020) and
optical (GSC 2.3.2, DES DR2) catalogs to establish associations with
infrared and optical sources and compared our results with previously
published counterparts in these bands. Requiring a detection in both
the infrared and optical bands to establish a candidate counterpart
for our X-ray detections, we obtain reliable counterparts for
18 sources, while the remaining two sources need further investigation
to establish firm identifications. In the infrared, we confirm
12 previously established counterparts and provide six new candidates.
In the optical, we find agreement with 13 previously established
counterparts, while we provide an alternative candidate for five SMS4
sources. We find that ∼35% of all the SMS4 sources lie below the lower
limit of 10.9Jy for the flux density at 178MHz established for the
3CRR sample, at variance with the values extrapolated using
measurements at higher frequencies. Therefore, for future studies
where flux-density-limited samples are needed, we encourage the use of
the more recent G4Jy sample. We present the list of 56 SMS4 sources
that in 2022 March remain to be observed in the X-rays with
narrow-field instruments, to highlight interesting sources and
organize further observational campaigns to achieve complete X-ray
coverage for the whole SMS4 in the forthcoming years.
Description:
The SMS4 sample comes from a compilation of the Molonglo Southern 4Jy
(MS4) sample which included 228 sources that were all imaged at 843MHz
with the Molonglo Observatory Synthesis Telescope (MOST) to establish
accurate positions, flux densities, and angular sizes. 133 MS4 sources
with largest angular size (LAS) <35" were also selected for
high-resolution imaging at 5GHz with the Australia Telescope Compact
Array (ATCA). Optical identification for all MS4 sources was pursued
complementing the analysis on plates from the UK Schmidt Southern Sky
Survey with R-band CCD images made with the Anglo-Australian Telescope
(AAT). Furthermore, spectral information at other frequencies was
collected from the literature to derive S178 for all MS4 sources.
Hence, by using the same flux density threshold S178* as in the
3CRR catalog (Laing+ 1983, J/MNRAS/204/151), a strong-source subset of
137 sources with S178≥S178*, called SMS4, was created.
In this paper, we report on a Swift observing program of the SMS4
sample, including 31 sources with no X-ray observations in the Chandra
or XMM-Newton archives. A total of 24 sources were observed for the
first time as a result of a dedicated proposal, while six were already
present in the Swift archive when our dedicated campaign started, in
2015 November. The remaining source, PKS B2148-555, was observed in
2019 February.
The Swift observations of the ensemble discussed here include 24
sources observed (mainly between 2015 November and 2016 September) as
part of an initial Swift proposal. Among these, five sources were
observed again between 2019 and 2021 by chance (MRC B1017-421 and
MRC B1036-697) or from subsequent Swift Target of Opportunities (ToO)
requests (MRC B0547-408, MRC B0906-682, and MRC1451-364).
In 2021 October, the 24 sources were then supplemented with archival
observations for seven additional sources: MRC B0157-311,
MRC B0407-658, MRC B0743-673, MRC B0842-754, MRC B1413-364,
MRC B1737-609, and PKSB2148-555. The full observational details are
given in Table 2 (for detections) and Table 3 (for upper limits).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 31 *List of correspondences established between the
31 SMS4 sources in our sample and the GLEAM 4Jy
(G4Jy) or TGSS-ADR1 sources
table2.dat 88 20 Swift-XRT detections of SMS4 sources of our sample
table3.dat 58 11 XRT count rate 3σ upper limits at the
position of the 11 SMS4 sources of our sample
not detected by Swift
table7.dat 79 20 Our candidate counterparts for X-ray-detected
SMS4 sources
table8.dat 71 56 SMS4 sources with no data (2021 September) from
narrow-field X-ray telescopes on board Swift,
Chandra, or XMM-Newton
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Note on table1.dat: A sample of the brightest radio sources in the southern sky
was generated from observations taken with the Murchison Widefield
Array (MWA) in the 72-231MHz range. MWA observations obtained during
the first year of operations produced the Galactic and Extragalactic
All-sky MWA (GLEAM; Wayth+ 2015PASA...32...25W 2015PASA...32...25W) Survey, from which the
Extragalactic Catalog (EGC; Hurley-Walker+ 2017, Cat. VIII/100) was built.
TGSS-ADR1=the 1st Alternative Data Release (ADR1) based on the survey at
150MHz, which was carried out with the Giant Metrewave Radio Telescope
(GMRT) as part of the TIFR GMRT Sky Survey (TGSS) project
(Intema+ 2017, J/A+A/598/A78).
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See also:
B/swift : Swift Master Catalog (HEASARC, 2004-)
VIII/1 : The 3C and 3CR Catalogues (Edge+ 1959-1962)
VIII/2 : Molonglo Reference Catalog of Radio Sources (Large+ 1981)
VIII/16 : Molonglo Reference Catalogue of Radio Sources (Large+ 1991)
VIII/35 : Radio Sources observed with Culgoora Circular Array (Slee 1995)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/78 : Sydney University Molonglo Sky Survey (SUMSS) (Mauch+ 2006)
VIII/81 : Sydney University Molonglo Sky Survey (SUMSS V2.1) (Mauch+ 2008)
II/328 : AllWISE Data Release (Cutri+ 2013)
VIII/100 : GaLactic and Extragalactic All-sky MWA survey (Hurley-Walker+, 2016)
VIII/105 : The GLEAM 4-Jy (G4Jy) Sample (White+, 2020)
I/353 : The Guide Star Catalog, Version 2.4.2 (GSC2.4.2) (STScI, 2020)
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
II/365 : CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)
J/MNRAS/204/151 : Bright radio sources at 178 MHz (3CRR) (Laing+ 1983)
J/ApJS/80/137 : Southern Extragalactic Radio Sources (Jones+, 1992)
J/AJ/131/100 : The Molonglo Southern 4Jy sample. I (Burgess+, 2006)
J/AJ/131/114 : The Molonglo Southern 4Jy sample. II (Burgess+, 2006)
J/MNRAS/371/898 : Extragalactic radio sources selected at 20GHz (Sadler+, 2006)
J/A+A/495/691 : Multifreq. catalog of blazars, Roma-BZCAT (Massaro+, 2009)
J/ApJS/186/378 : Hard X-ray survey from Swift-BAT 2004-2006 (Tueller+, 2010)
J/ApJ/734/L34 : 145MHz source measurements by PAPER (Jacobs+, 2011)
J/ApJ/751/52 : AGN cand. from the WISE, 2MASS, RASS (W2R) (Edelson+, 2012)
J/ApJS/206/17 : New gamma-ray blazar candidates in the 3PBC (Maselli+, 2013)
J/ApJS/221/12 : AGNs in the MIR using AllWISE data (Secrest+, 2015)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/A+A/598/A78 : The GMRT 150MHz all-sky radio survey (Intema+, 2017)
J/A+A/624/A145 : Astrometric Catalogue 5, LQAC-5 (Souchay+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Cat G4Jy sample or TGSS-ADR1
6- 14 A9 --- SMS4 SMS4 name according to the MRC or
PKS (for B2148-555 only) designation
(BHHMM+DDd)
16 A1 --- n_SMS4 Note on SMS4 (1)
18- 21 F4.1 Jy S178 [11/59] Extrapolated flux density S178
23- 25 I3 arcsec LAS [10/780] the largest angular size of
the radio source at 843MHz
27 A1 --- l_z Lower limit flag on z
28- 34 F7.5 --- z [0.038/1.52] Redshift
36 A1 --- n_z p=photometric
38- 53 A16 --- Name IAU name in G4Jy according to the GLEAM
designation or in TGSS-ADR1 (JHHMMSS+DDMMSS)
55- 58 I4 --- G4Jy [20/1732]? G4Jy identifier
60- 61 I2 h RAh Hour of right ascension (J2000)
63- 64 I2 min RAm Minute of right ascension (J2000)
66- 70 F5.2 s RAs Second of right ascension (J2000)
72 A1 --- DE- Sign of declination (J2000)
73- 74 I2 deg DEd Degree of declination (J2000)
76- 77 I2 arcmin DEm Arcminute of declination (J2000)
79- 82 F4.1 arcsec DEs Arcsecond of declination (J2000)
84- 88 F5.2 Jy Flux [6.2/50.04] Actual flux density (2)
90- 93 F4.2 Jy e_Flux [0.01/1.32] Flux uncertainty
95 A1 --- Morph Radio source morphology (3)
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Note (1): Flag as follows:
a= For this source two TGSS components, matching the lobes of the radio
galaxy in the ATCA map published in BH06 (Burgess & Hunstead,
2006, J/AJ/131/100 and J/AJ/131/114), are found.
The coordinates reported in this table, matching the core, come
from SUMSS (Mauch+ 2003, VIII/81).
Note (2): The actual flux density: S181 for G4Jy, or S150 for TGSS-ADR1.
Note (3): The radio source morphology, following W20 (White+, 2020, VIII/105):
s = single (21 occurrences)
d = double (4 occurrences)
t = triple (3 occurrences)
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh X-ray detection hour of right ascension (J2000)
4- 5 I2 min RAm X-ray detection minute of RA (J2000)
7- 11 F5.2 s RAs X-ray detection second of RA (J2000)
13 A1 --- DE- X-ray detection sign of declination (J2000)
14- 15 I2 deg DEd X-ray detection degree of declination (J2000)
17- 18 I2 arcmin DEm X-ray detection arcminute of DEC (J2000)
20- 23 F4.1 arcsec DEs X-ray detection arcsecond of DEC (J2000)
25- 27 F3.1 arcsec ePos [3.6/6.5] Positional error radius at the 90%
confidence level
29- 33 F5.1 10-3ct/s CRte [1.3/190.1] 0.3-10keV count rate in
10-3counts/s
35- 37 F3.1 10-3ct/s e_CRte [0.6/8.8] CRte uncertainty
39 A1 --- l_P Limit flag on P
40- 46 E7.2 --- P Probability, P, that the signal is a
statistical fluctuation of the background
48- 57 A10 "Y/M/D" Date1 First date of Swift observation (UT)
59- 68 A10 "Y/M/D" Date2 Latest date of Swift observation (UT)
70- 71 I2 --- Nobs [1/15] Number of Swift observations
73- 76 I4 s Exp [1221/9203] Exposure time
78- 86 A9 --- SMS4 Name of the corresponding SMS4 source
according to MRC designation (BHHMM+DDd)
88 A1 --- n_SMS4 b=sources in our initial Swift proposal
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cat MRC or PKS designation
5- 13 A9 --- SMS4 SMS4 name (BHHMM+DDd)
15 A1 --- n_SMS4 b=sources in our initial Swift proposal
17- 26 A10 "Y/M/D" Date1 First date of Swift observation (UT)
28- 37 A10 "Y/M/D" Date2 Latest date of Swift observation (UT)
39- 40 I2 --- Nobs [1/13] Number of Swift observations
42- 45 I4 s Exp [1075/6453] Total XRT exposure time
47- 53 E7.2 --- P [0.0054/1] Probability, P, that the signal is a
statistical fluctuation of the background
55- 58 F4.1 --- Lim [2.1/14.9] 0.3-10keV count rate upper limit at
the position of the radio coordinates
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- SMS4 SMS4 name (BHHMM+DDd)
11 A1 --- f_SMS4 Flag on SMS4 (1)
13 A1 --- Cl Object class (A=unique candidate counterpart) (2)
15- 16 A2 --- IRCat Infrared catalog identification (3)
18- 36 A19 --- IRId Infrared source identification
(JHHMMSS.ss+DDMMSS.s)
38 A1 --- f_IRId Flag on IRId (1)
40- 44 F5.2 mag W1mag [11.55/17.09] WISE W1 (3.4um) band magnitude
46- 49 F4.2 mag W1-W2 [0.25/1.52] W1-W2 color index
51- 74 A24 --- OID Optical source identification
76- 79 F4.2 arcsec delta [0.11/1.55] the angular separation Δ
between the given infrared and optical sources
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Note (1): Flag as follows:
a = This infrared source was previously associated by W20.
b = Bright infrared source, at the boundaries of the XRT 99% positional
uncertainty, with WISE AGN-like colors.
c = Extended radio galaxy (see Figure 1), with low-frequency G4Jy centroid
not reliably matching the core; the BH06 optical counterpart lies 2.6"
from the GSC 2.3.2 source.
d = The BH06 counterpart lies ∼2.5" from the GSC 2.3.2 source; the AllWISE
source lies between these optical sources.
e = Extended radio galaxy (see Figure 1), with low-frequency G4Jy centroid
not reliably matching the core; the XRT positional uncertainty (90% c.l)
includes only one of two close sources.
f = Candidate matching the SUMSS C component of an extended radio galaxy,
consistent with its radio core.
g = As discussed in the text, there are two viable counterparts. The given
source IDs are those that include, as an optical counterpart, the one
suggested in BH06 (the green plus sign in Figure 2).
Note (2): The class, reflecting the reliability of the candidate's association
Class A sources are those whose candidate counterpart is unique since
it lies within the XRT positional uncertainty at the 90% confidence
level and shows typical AGN colors. Class B sources are those having
more than one plausible candidate within, or in the proximity of, the
XRT positional uncertainty (90% c.l); see Section 5.2.
Note (3): Catalog as follows:
AW = AllWISE, Cutri+ 2014, II/328
CW = CatWISE2020, Marocco+ 2021, II/365
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cat MRC or PKS designation
5- 13 A9 --- SMS4 SMS4 name (BHHMM+DDd)
15 A1 --- n_SMS4 b=accepted in 2021 October for observation
with Swift
17- 18 I2 h RAh Hour of right ascension (J2000)
20- 21 I2 min RAm Minute of right ascension (J2000)
23- 27 F5.2 s RAs Second of right ascension (J2000)
29 A1 --- DE- Sign of declination (J2000)
30- 31 I2 deg DEd Degree of declination (J2000)
33- 34 I2 arcmin DEm Arcminute of declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of declination (J2000)
41 A1 --- l_z Lower limit flag on z
42- 48 F7.5 --- z [0.03/1.92]? Redshift
49 A1 --- n_z P=photometric
51- 54 F4.1 Jy S178 [11/44] Extrapolated flux density S178 from
SMS4
56- 59 F4.1 Jy S181 [5.5/34.6] Total integrated flux density S181
from G4Jy
61- 64 I4 arcsec LAS [10/1536] Largest angular size of the radio
source at 843MHz
66- 67 A2 --- RCl Structural classification of the radio source (1)
69- 71 A3 --- OCl Classification of the associated optical
counterpart (2)
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Note (1): The structural classification of the radio source, following
Fanaroff & Riley (1974MNRAS.167P..31F 1974MNRAS.167P..31F):
2 = FR2 double (29 occurrences);
D2 = double, with one component coincident with the optical counterpart
(1 occurrence);
T = core-dominated triple (2 occurrences);
c = structure not resolved well enough to classify (5 occurrences).
Note (2): The classification of the associated optical counterpart:
d = extended radio source with more than one candidate;
e = compact radio source with large radio-optical offset;
g = galaxy;
Q = quasar;
Q? = quasar candidate;
BF = blank field;
O = field obscured by star.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 22-Nov-2022