J/ApJS/247/57 Compact bright radio-loud AGNs. III. VLBA 43GHz (Cheng+, 2020)
Compact bright radio-loud AGNs.
III. A large VLBA survey at 43 GHz.
Cheng X.-P., An T., Frey S., Hong X.-Y., He X., Kellermann K.I.,
Lister M.L., Lao B.-Q., Li X.-F., Mohan P., Yang J., Wu X.-C., Zhang Z.-L.,
Zhang Y.-K., Zhao W.
<Astrophys. J. Suppl. Ser., 247, 57 (2020)>
=2020ApJS..247...57C 2020ApJS..247...57C
ADC_Keywords: Active gal. nuclei; Radio sources; Interferometry; QSOs
Keywords: Very long baseline interferometry ; Active galaxies ; Surveys ;
Radio loud quasars ; Jets
Abstract:
We present the results from the 43GHz Very Long Baseline Array (VLBA)
observations of 124 compact radio-loud active galactic nuclei (AGNs)
that were conducted between 2014 November and 2016 May. The typical
dimensions of the restoring beam in each image are about 0.5masx0.2mas.
The highest resolution of 0.2mas corresponds to a physical size of
0.02pc for the lowest redshift source in the sample. The 43GHz very
long baseline interferometry (VLBI) images of 97 AGNs are presented
for the first time. We study the source compactness on milliarcsecond
and submilliarcsecond scales, and suggest that 95 sources in our
sample are suitable for future space VLBI observations. By analyzing
our data supplemented with other VLBA AGN surveys from the literature,
we find that the core brightness temperature increases with increasing
frequency below a break frequency ∼7GHz, and decreases between ∼7 and
240GHz but increases again above 240GHz in the rest frame of the
sources. This indicates that the synchrotron opacity changes from
optically thick to thin. We also find a strong statistical correlation
between radio and γ-ray flux densities. Our correlation is
tighter than those in the literature derived from lower-frequency VLBI
data, suggesting that the γ-ray emission is produced more
cospatially with the 43GHz VLBA core emission. This correlation can
also be extrapolated to the unbeamed AGN population, implying that a
universal γ-ray production mechanism might be at work for all
types of AGNs.
Description:
The VLBA observations were spread over a period of almost one
year from 2015 June to 2016 April (observation codes BA111G-BA111I and
BA111J-BA111M). All 10 VLBA antennas were used for the 43GHz
observations.
In Paper II (Chen+, 2018ApJ...852...17C 2018ApJ...852...17C), VLBA observations over 2014
Dec 21 to 2016 May 6 (observation code BA111A-BA111F) were presented.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 69 124 General source properties
table3.dat 69 124 Image parameters
table4.dat 54 341 Model fit parameters of sources
notes.dat 868 62 Notes
--------------------------------------------------------------------------------
See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VII/248 : Quasars and Active Galactic Nuclei (12th Ed.) (Veron+ 2006)
J/MNRAS/204/151 : Bright radio sources at 178 MHz (3CRR) (Laing+ 1983)
J/ApJS/98/1 : First Caltech-Jodrell Bank VLBI Survey. I. (Polatidis+ 1995)
J/A+AS/131/303 : GHz-Peaked-Spectrum radio sources (Stanghellini+ 1998)
J/A+A/363/887 : High frequency peakers. I. Bright sample (Dallacasa+, 2000)
J/ApJS/128/17 : VLBA obs. of radio reference frame sources. III. (Fey+, 2000)
J/ApJS/131/95 : VSOP 5 GHz continuum survey (Fomalont+, 2000)
J/ApJS/141/13 : VLBA calibrator survey: VCS1 catalog (Beasley+, 2002)
J/AJ/126/2562 : Second VLBA calibrator survey: VCS2 (Fomalont+, 2003)
J/PASJ/55/351 : ATCA observations of 202 compact radio sources (Tingay+, 2003)
J/AJ/127/3587 : VLBI ICRF. II (Fey+, 2004)
J/ApJ/616/110 : VSOP 5GHz AGN Survey. IV (Horiuchi+, 2004)
J/ApJS/155/33 : VSOP 5 GHz AGN Survey. III (Scott+, 2004)
J/AJ/130/2473 : Fine-scale structure in 250 sources at 15GHz (Kovalev+, 2005)
J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005)
J/A+A/450/959 : VLBA images of High Frequency Peakers (Orienti+, 2006)
J/A+A/476/L17 : 86 and 43GHz observations of NRAO 150 (Agudo+, 2007)
J/ApJS/171/376 : MOJAVE. III. VLA 1.4GHz images (Cooper+, 2007)
J/ApJ/658/203 : VLBA imaging and polarimetry survey at 5GHz (Helmboldt+, 2007)
J/ApJS/175/314 : VSOP 5GHz AGN survey V. (Dodson+, 2008)
J/AJ/136/159 : Global 86GHz VLBI survey of compact radio sources (Lee+, 2008)
J/AJ/138/1874 : MOJAVE. VI. Kinematic analysis of blazar jets (Lister+, 2009)
J/ApJS/189/1 : A 3.5mm polarimetric survey of radio-loud AGNs (Agudo+, 2010)
J/AJ/139/1713 : Celestial Reference Frame at 24 and 43GHz. II (Charlot+, 2010)
J/ApJ/710/764 : Extended radio emission in MOJAVE blazars (Kharb+, 2010)
J/AJ/139/1695 : Celestial Reference Frame at 24 and 43 GHz (Lanyi+, 2010)
J/ApJ/741/30 : Radio/γ-ray correlation in AGN (Ackermann+, 2011)
J/A+A/535/A69 : AGN Fermi/LAT γ-ray and 37GHz fluxes (Nieppola+, 2011)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
J/ApJ/758/84 : Relativistic jets in RRFID database. II. 10yr (Piner+, 2012)
J/A+A/544/A34 : Bright AGN VLBI imaging study at 2 and 8GHz (Pushkarev+, 2012)
J/AJ/146/120 : MOJAVE. X. Parsec-scale kinematics of AGNs (Lister+, 2013)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJ/810/14 : Third catalog of LAT-detected AGNs (3LAC) (Ackermann+, 2015)
J/AJ/150/58 : VLBI ICRF2 (Fey+, 2015)
J/ApJS/226/20 : X-ray, opt. & radio SEDs of Fermi blazars (Fan+, 2016)
J/AJ/152/12 : MOJAVE. XIII. New 15GHz obs. on 1994-2013 (Lister+, 2016)
J/ApJ/846/98 : Jet kinematics of blazars at 43GHz with VLBA (Jorstad+, 2017)
J/A+A/622/A92 : Ultracompact radio sources at 86GHz (Nair+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- ID Identifier (HHMM+DDMM; B1950)
10- 18 A9 --- OName Source alias
20 A1 --- Set [BC] Observing session (G1)
22- 23 I2 h RAh Hour of Right Ascension (J2000)
25- 26 I2 min RAm Minute of Right Ascension (J2000)
28- 35 F8.5 s RAs Second of Right Ascension (J2000)
37 A1 --- DE- Sign of the Declination (J2000)
38- 39 I2 deg DEd Degree of Declination (J2000)
41- 42 I2 arcmin DEm Arcminute of Declination (J2000)
44- 50 F7.4 arcsec DEs Arcsecond of Declination (J2000)
52- 56 F5.3 --- z [0.004/3.3]? Spectroscopic redshift
58- 63 A6 --- Class Optical classification (1)
65 A1 --- Note [NY] Source comments (see notes.dat file)
67- 69 I3 10-10ph/cm2/s SGam [4/401]? Fermi-LAT 100MeV-300GeV flux
(from Acero+ 2015, J/ApJS/218/23)
--------------------------------------------------------------------------------
Note (1): Classification as follows:
QSO = quasar (97 sources);
BL Lac = BL Lac object (15 sources);
G = active galaxy (6 sources);
U = unidentified (6 sources).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- ID Identifier (HHMM+DDMM; B1950)
10- 19 A10 "Y/M/D" Date Observation date
21- 24 F4.2 mas Bmaj [0.39/0.94] FWHM of restoring beam major axis
26- 29 F4.2 mas Bmin [0.14/0.31] FWHM of restoring beam minor axis
31- 35 F5.1 deg BPA [-30/40.7] Position angle of major axis
measured from north through east
37- 41 F5.3 Jy Stot [0.1/3] Integrated flux density
43- 47 F5.3 Jy/beam Speak [0.07/2.8] Peak specific intensity
49- 52 F4.2 mJy/beam sigma [0.1/2.7] Off-source rms noise in clean image
54- 57 F4.2 Jy SS [0.1/2.9] Shortest baseline correlated
flux density
59- 60 I2 --- BS [17/85] Shortest baseline length
in million wavelengths units
62- 65 F4.2 Jy SL [0.04/2.9] Longest baseline correlated
flux density
67- 69 I3 --- BL [204/540] Longest baseline length
in million wavelengths units
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- ID Identifier (HHMM+DDMM; B1950)
10- 10 A1 --- Set [BC] Observing session (G1)
12- 13 A2 --- m_ID Component identifier
15- 19 F5.3 Jy Stot [0.004/2.9] Fitted Gaussian model component
integrated flux density
21- 25 F5.3 Jy/beam Speak [0.001/2.8] Peak intensity
27- 30 F4.2 mas R [0.1/7.1]? Radial distance from the core
32- 38 F7.2 deg PA [-180/179]? Position angle with respect
to the core
40- 40 A1 --- l_d Limit flag on d
41- 45 F5.2 mas d [0.01/1.9] Component size
47- 47 A1 --- l_Tb Limit flag on Tb
48- 54 F7.2 10+10K Tb [0.04/254.4]? Core brightness temperature
--------------------------------------------------------------------------------
Byte-by-byte Description of file: notes.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- ID IAU identifier (HHMM+DDMM; B1950)
10- 18 A9 --- OName Other name
21-868 A848 --- Note Text of the note
--------------------------------------------------------------------------------
Global notes:
Note (G1): To ensure the success of the observations, we split the sources into
two subsamples, based on the source flux densities measured at lower
radio frequencies. The first subsample consists of 40 bright sources
for which we acquired good images, while the second subsample includes
84 relatively weaker sources, which were observed less thoroughly.
These subsamples were observed in the corresponding sessions "B" and "C".
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
An et al. Paper I. 2014Ap&SS.352..825A 2014Ap&SS.352..825A
Cheng et al. Paper II. 2018ApJS..234...17C 2018ApJS..234...17C
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Jun-2020