J/AJ/164/122 Radio structure in z∼0.25 radio-quiet QSOs (McCaffrey+, 2022)
Kiloparsec-scale Radio Structure in z∼0.25 Radio-quiet QSOs.
McCaffrey T.V., Kimball A.E., Momjian E., Richards G.T.
<Astron. J., 164, 122 (2022)>
=2022AJ....164..122M 2022AJ....164..122M
ADC_Keywords: QSOs; Active gal. nuclei; Radio sources; Optical; Redshifts
Keywords: Radio quiet quasars ; Active galaxies ; Direct imaging
Abstract:
We present analysis of a homogeneous, optically selected,
volume-limited (0.2<z<0.3) sample of 128 radio-quiet quasi-stellar
objects (QSOs) recently observed at 6GHz with the Very Large Array
(VLA) in A configuration (∼0.33" resolution). We compare these new
results to earlier (2010-2011) 6GHz observations with the VLA in C
configuration (∼3.5"). While all of these radio-quiet QSOs (RQQs) were
unresolved on a 3.5" scale (∼14kpc at z=0.25), we resolve notable
complex subgalactic structures in about half of the RQQs at 0.33"
resolution (∼1.3kpc at z=0.25). By comparison of flux density
measurements between the two sets of observations, we demonstrate that
significant sub-galactic-scale radio structure is present in at least
70% of the RQQ population and that the central component accounts for
an average of ∼65% of the total detected radio power. One RQQ,
J0935+4819, shows striking symmetric, double-lobed morphology and
appears to be the first identified example of a radio-quiet QSO with
FRII type morphology on ∼arcsec scale (projected size of ≳6kpc). In
addition to revealing RQQ subgalactic morphology, we employ
counterparts from legacy (FIRST at 1.4GHz) and recent (VLA Sky Survey
at 3GHz) VLA surveys to investigate radio spectral indices and
potential variability over decades-long timescales for a subset of the
RQQs and for the cores of radio-intermediate and radio-loud sources in
the parent sample of 178 QSOs. These results support the growing
notion that the RQQ population is not a monolithic phenomenon but
instead consists of a mixture of mainly starburst-powered and
jet-powered galaxies.
Description:
Both sets of observations were performed in the radio astronomy
"C-band," which comprises the frequency range 4-8 GHz. The 2010-2011
observations were performed during the commissioning and verification
phase of the upgrade from the legacy Very Large Array (VLA) hardware
and software to the new Karl G.Jansky VLA. As only 2GHz of bandwidth
was available for C-band observations at that time, the original set
of observations covered the frequency range 5-7GHz. The 2019
observations used the full 4-8GHz range of the C-band receiver by
utilizing two pairs of the VLA's 3bit samplers in each antenna.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 93 128 Target quasar radio properties
table2.dat 49 128 Target quasar optical properties
table5.dat 123 70 Multi-frequency data
--------------------------------------------------------------------------------
See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)
J/ApJ/269/352 : Quasar evolution (Schmidt+, 1983)
J/AJ/142/3 : 1.4GHz observations of Stripe 82 (Hodge+, 2011)
J/AJ/141/182 : Radio and optical properties of QSOs (Kimball+, 2011)
J/ApJ/742/49 : Variable & transient radio sources FIRST (Thyagarajan+, 2011)
J/ApJ/768/37 : Radio emission from SDSS quasars (Condon+, 2013)
J/ApJ/799/10 : Arp 220 6 and 33GHz images (Barcos-Munoz+, 2015)
J/ApJ/831/168 : 6GHz JVLA observations low-z SDSS quasars (Kellermann+, 2016)
J/MNRAS/455/4191 : Radio emission from radio-quiet quasars (Zakamska+, 2016)
J/A+A/607/A132 : VLBA observations of the COSMOS field (Herrera Ruiz+, 2017)
J/ApJS/230/7 : Spectral flux densities from 50MHz to 50GHz (Perley+, 2017)
J/A+A/602/A1 : VLA-COSMOS 3 GHz Large Project (Smolcic+, 2017)
J/A+A/609/A1 : FR0CAT. a FIRST catalog of FR 0 radio galaxies (Baldi+, 2018)
J/A+A/622/A1 : LOFAR 2metre Sky Survey DR1 source catalog (Shimwell+, 2019)
J/other/AstBu/74.348 : 164 GHz-peaked spectrum sources (Sotnikova+, 2019)
J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS identifier; SDSS JHHMMSS.SS+DDMMSS.S
20- 24 F5.1 uJy/beam Flux [11.4/581] Peak 6GHz flux density (1)
26- 29 F4.1 uJy/beam e_Flux [0/17] Uncertainty in Flux6
31- 35 F5.1 uJy Core [11.4/581] Core 6GHz flux density (1)
37- 40 F4.1 uJy e_Core [0/22] Uncertainty in Core6
42- 46 F5.1 uJy Tot [11.4/670] Total 6 GHz flux density (1)
48- 52 F5.1 uJy e_Tot [0/101] Uncertainty in STot
54- 57 F4.1 uJy/beam sigma [3.6/10.5] RMS noise of radio image
59- 62 F4.2 --- Rati [0.08/1] Core to total flux density ratio
64- 67 F4.2 --- A/C [0.2/2.6] Ratio of total 6GHz flux density (2)
69- 73 F5.2 [W/Hz] logL [21.4/23.2] log 6GHz luminosity (3)
75- 76 A2 --- Morph Morphology (4)
78- 81 I4 mas MajAxis [0/2040] Major axis of taget's size (5)
83- 85 I3 mas e_MajAxis [0/220] Uncertainty in MajAxis
87- 89 I3 mas MinAxis [0/980] Minor axis of taget's size (5)
91- 93 I3 mas e_MinAxis [0/136] Uncertainty in MinAxis
--------------------------------------------------------------------------------
Note (1): From the VLA at ∼0.33" resolution with uncertainties computed by
the imfit task in CASA; for Unresolved sources and Resolved sources
whose core component is Unresolved and clearly separated from its
extended emission, Flux6 and Core6 are equal.
Note (2): Between our measured total 6GHz flux density at 0.33" and that
measured at 3.5" in Kellermann+, 2016, J/ApJ/831/168.
Note (3): Computed with total flux densities.
Note (4): At 0.33" determined by eye (see Section 4 for a description
of morphologies).
Note (5): Deconvolved with the beam using the imfit task in CASA; upper limits
are given for unresolved sources and no estimate is available for
sources too faint to derive an accurate size.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS identifier; SDSS JHHMMSS.SS+DDMMSS.S
20- 24 F5.3 --- z [0.2/0.3] SDSS DR7 Spectroscopic redshift
26- 30 F5.3 arcsec Delta [0.0/6.2] Closest detected radio component angular
offset (1)
32- 37 F6.2 mag iMag [-25.3/-23.3] Absolute i band AB magnitude
39- 43 F5.2 mag imag [15.3/17.3] Apparent i band AB magnitude
45- 49 F5.2 [-] logRi [-1.99/0.07] log ratio of6 GHz and i-band flux
densities (2)
--------------------------------------------------------------------------------
Note (1): From its optical position; typical uncertainties in the optical
positions of SDSS quasars are ∼0.1".
Note (2): Total 6GHz flux density at 0.33".
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS identifier; SDSS JHHMMSS.SS+DDMMSS.S
20- 24 F5.3 --- z [0.2/0.3] SDSS DR7 Spectroscopic redshift
26- 31 F6.2 mJy F6f [0.37/324] FIRST catalog 1.4GHz flux density
(1)
33- 36 F4.2 mJy e_F6f [0/1.9] Uncertainty in F6f
38- 41 I4 yr Datef.Y [1993/2003] Year of FIRST observation
43- 44 I2 "month" Datef.M Month of FIRST observation
46- 47 I2 d Datef.D Day of FIRST observation
49- 54 F6.2 mJy F6vc [0.13/322] VLA's C configuration 6GHz flux
density (2)
56- 59 F4.2 mJy e_F6vc [0.01/9.66] Uncertainty in F6vc
61- 64 I4 yr Datevc.Y [2010/2011] Year of VLAC observation
66- 67 I2 "month" Datevc.M Month of VLAC observation
69- 70 I2 d Datevc.D ? Day of VLAC observation
72- 77 F6.2 mJy F3vs [0.33/394] Epoch1 VLASS 3GHz flux density (3)
79- 83 F5.2 mJy e_F3vs [0/85] Uncertainty in F3vs
85- 88 I4 yr Dates.Y [2017/2020] Year of VLASS observation
90- 91 I2 "month" Dates.M Month of VLASS observation
93- 94 I2 d Dates.D Day of VLASS observation
96- 99 F4.2 mJy F6a [0.11/0.67]? VLA's A configuration 6GHz flux
density (4)
101-104 F4.2 mJy e_F6a [0.01/0.1]? Uncertainty in F6a
106-109 A4 yr Datea.Y [2019]? Year of VLAA observation
111-112 I2 "month" Datea.M ? Month of VLAA observation
114-115 I2 d Datea.D ? Day of VLAA observation
117-118 A2 --- Class Classification (5)
120-123 F4.1 --- alpha [-0.7/0] Spectra index (6)
--------------------------------------------------------------------------------
Note (1): Measured total 1.4GHz flux density of each source as it appeared
in FIRST (Becker+, 1995ApJ...450..599B 1995ApJ...450..599B.
Note (2): Total 6GHz flux density measured by Kellermann+, 2016, J/ApJ/831/168
in the VLA's C configuration (∼3.5" at a 6GHz reference frequency).
Note (3): Measured total 3GHz flux density in Epoch 1 of VLASS
(Lacy+, 2020PASP..132c5001L 2020PASP..132c5001L).
Note (4): Measured total 6GHz flux density of source in the VLA's A
configuration (∼0.33" at a 6GHz reference frequency).
Note (5): Source's radio-loud/-intermediate/-quiet classification based on
6GHz luminosities measured by Kellermann+, 2016, J/ApJ/831/168. See
Section 2 for how "radio-quietness" is defined.
Note (6): Obtained through the time-domain analysis explained in Section 5.3.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 21-Nov-2022