J/ApJ/893/68 RadioAstron. III. S5 0716+71 at uarcsec res. (Kravchenko+, 2020)
Probing the innermost regions of AGN jets and their magnetic fields with
RadioAstron.
III. Blazar S5 0716+71 at microarcsecond resolution.
Kravchenko E.V., Gomez J.L., Kovalev Y.Y., Lobanov A.P., Savolainen T.,
Bruni G., Fuentes A., Anderson J.M., Jorstad S.G., Marscher A.P.,
Tornikoski M., Lahteenmaki A., Lisakov M.M.
<Astrophys. J., 893, 68 (2020)>
=2020ApJ...893...68K 2020ApJ...893...68K
ADC_Keywords: Interferometry; BL Lac objects; Radio sources
Keywords: Interferometry ; Active galactic nuclei ; BL Lacertae objects ;
Blazars ; Jets ; Relativistic jets
Abstract:
We present RadioAstron Space VLBI imaging observations of the BL Lac
object S5 0716+71 made on 2015 January 3-4 at a frequency of 22GHz
(wavelength λ=1.3cm). The observations were made in the
framework of the AGN Polarization Key Science Program. The source was
detected on projected space-ground baselines up to 70833km (5.6 Earth
diameters) for both parallel-hand and cross-hand interferometric
visibilities. We have used these detections to obtain a
full-polarimetric image of the blazar at an unprecedented angular
resolution of 24µas, the highest for this source to date. This
enabled us to estimate the size of the radio core to be <12x5µas
and to reveal a complex structure and a significant curvature of the
blazar jet in the inner 100µas, which is an indication that the jet
viewing angle lies inside the opening angle of the jet conical
outflow. Fairly highly (15%) linearly polarized emission is detected
in a jet region 19µas in size, located 58µas downstream from the
core. The highest brightness temperature in the source frame is
estimated to be >2.2x1013K for the blazar core. This implies that
the inverse-Compton limit must be violated in the rest frame of the
source, even for the largest Doppler factor δ∼25 reported for
0716+714.
Description:
The RadioAstron imaging experiment on S5 0716+71 was performed in
2015 January 3-4 at 22.2GHz during a 12hr space VLBI session
(RadioAstron project code raks11aa, global VLBI project code GL041A).
Twelve ground antennas delivered data that could be used for the
correlation. See Section 2.1.
Metsahovi Radio Observatory has a dedicated program to monitor a
sample of extragalactic radio sources, including bright AGNs, that has
been running since 1980 using 13.7m diameter antenna. The program
comprises regular observations of the total flux density mainly at
22 and 37GHz. We made use of these 37GHz data in our analysis.
Our study makes use of 43GHz VLBA data from the VLBA-BU-BLAZAR
monitoring program. A total of 50 epochs of 0716+714 were used,
covering the period from 2012 January 27 until 2017 April 16, with an
approximately monthly cadence. Further details about the
VLBA-BU-BLAZAR program and the calibration of these data can be found
in Jorstad+ (2017, J/ApJ/846/98).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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07 21 53.45 +71 20 36.4 S5 0716+71 = 8C 0716+714
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 109 27 Results of decomposition of 37GHz light curve into
individual flares and model fitted results for
the core component at 43GHz at corresponding epochs
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See also:
VIII/5 : Bright Extragalactic Radio Sources (1Jy) (Kuehr+, 1981)
J/A+AS/132/305 : Extragal. radio sources at 22, 37 and 87GHz (Terasranta+ 1998)
J/AJ/130/2473 : Fine-scale structure in 250 sources at 15GHz (Kovalev+, 2005)
J/AJ/146/120 : MOJAVE. X. Parsec-scale kinematics of AGNs (Lister+, 2013)
J/ApJ/783/83 : BVRI photometry of S5 0716+714 (Liao+, 2014)
J/A+A/604/A111 : 22GHz image of 3C 273 (Bruni+, 2017)
J/ApJ/846/98 : Jet kinematics of blazars at 43GHz with VLBA (Jorstad+, 2017)
J/MNRAS/468/4992 : MOJAVE XIV. AGN jets & opening angles (Pushkarev+, 2017)
J/ApJS/234/12 : MOJAVE XV. 15GHz obs. of AGN jets 1996-2016 (Lister+, 2018)
J/A+A/619/A45 : S5 0716+714 multi-wave. curves (MAGIC Collaboration+, 2018)
J/ApJ/874/43 : MOJAVE. XVII. Parsec-scale jet kinematics (Lister+, 2019)
J/A+A/622/A92 : Ultracompact radio sources at 86GHz (Nair+, 2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Flare [1/27] Running sequence number
4- 7 F4.2 Jy Smax [1.1/5.4] Maximum amplitude
9- 12 F4.2 Jy e_Smax [0.03/0.5] Uncertainty in Smax
14- 20 F7.2 yr tmax [2012.14/2016.92] Epoch of the flare
maximum (1)
22- 26 F5.3 yr tauvar [0.003/0.5] Flare rise timescale
28- 32 F5.3 yr e_tauvar [0.001/0.06] Uncertainty in tauvar
34- 38 F5.2 [K] logTb [12.24/16.63] Log variability brightness
temperature
40- 43 F4.2 [K] e_logTb [0.04/0.6] Uncertainty in logTb
45- 48 F4.1 --- delVar Variability Doppler factor
50- 53 F4.2 Jy Score [1.9/3.5]? Core flux density
55- 58 F4.2 Jy e_Score [0.1/0.2]? Uncertainty in Score
60 A1 --- f_Score [bc] Flag on Score (2)
62- 68 F7.2 yr BU [2012.83/2016.91]? Epoch of nearby BU
observations
70- 74 F5.2 uarcsec Size [16.5/47.1]? Radio core size
76- 78 F3.1 uarcsec e_Size [0.4/3]? Uncertainty in Size
80- 84 F5.2 [K] logTbrf [12.1/12.9]? Log rest frame brightness
temperature (3)
86- 89 F4.2 [K] e_logTbrf [0.02/0.08]? Uncertainty in logTb,rf
91- 95 F5.2 [K] logTbint [11.2/12.2]? Log intrinsic brightness
temperature
97- 100 F4.2 [K] e_logTbint [0.05/0.4]? Uncertainty in logTb,int
102- 105 F4.1 --- delta [1.3/14.5]? Doppler factor
107- 109 F3.1 --- e_delta [0.1/1]? Uncertainty in delta
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Note (1): Typical error is of the order of a day.
Note (2): Flag as follows:
b = Fitted model is not reliable.
c = The core is modelled by elliptical Gaussian component.
Note (3): Corrected for redshift and not corrected for Doppler boosting.
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History:
From electronic version of the journal
References:
Gomez et al. Paper I. 2016ApJ...817...96G 2016ApJ...817...96G
Bruni et al. Paper II. 2017A&A...604A.111B 2017A&A...604A.111B Cat. J/A+A/604/A111
Kravchenko et al. Paper III. 2020ApJ...893...68K 2020ApJ...893...68K This catalog
Potzl et al. Paper IV. 2021A&A...648A..82P 2021A&A...648A..82P Cat. J/A+A/648/A82
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Sep-2021