J/A+A/601/A12 S5 0716+714 VLBI K- and Q-band variability (Lee+, 2017)
Simultaneous dual-frequency radio observations of S5∼0716+714:
A search for intraday variability with the Korean VLBI Network.
Lee J.W., Sohn B.W., Byun D.-Y., Lee J.A., Kim S.S.
<Astron. Astrophys. 601, A12 (2017)>
=2017A&A...601A..12L 2017A&A...601A..12L (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Radio sources ; VLBI
Keywords: galaxies: active -
galaxies: BL Lacertae objects: individual: S5 0716+714 -
galaxies: jets - radio continuum: galaxies
Abstract:
This study aims to search for the existence of intraday variability
(IDV) of BL Lac object S5 0716+714 at high radio frequencies for which
the interstellar scintillation effect is not significant. Using the
21-m radio telescope of the Korean VLBI Network (KVN), we present
results of multi-epoch simultaneous dual-frequency radio observations.
Single-dish observations of S5 0716+714 were simultaneously conducted
at 21.7GHz (K-band) and 42.4GHz (Q-band), with a high cadence of
30-60min intervals. We observed four epochs between December 2009 and
June 2010. Over the whole set of observation epochs, S5 0716+714
showed significant inter-month variations in flux density at both the
K- and Q-bands, with modulation indices of approximately 19% for the
K-band and approximately 36% for the Q-band. In all epochs, no clear
intraday variability was detected at either frequency. The source
shows monotonic flux density increase in epochs 1 and 3 and monotonic
flux density decrease in epochs 2 and 4. In the flux density
increasing phases, the flux densities at the Q-band increase more
rapidly. In the decreasing phase, no significant flux density
difference is seen at the two frequencies. The situation could be
different close to flux density peaks that we did not witness in our
observations. We find an inverted spectrum with mean spectral indices,
{bar}α(Sν∝ν-α), of -0.57±0.13 in epoch
1 and -0.15±0.11 in epoch 3. On the other hand, we find relatively
steep indices of +0.24±0.14 and +0.17±0.18 in epochs 2 and 4,
respectively. We conclude that the frequency dependence of the
variability and the change of the spectral index are caused by
source-intrinsic effects rather than by any extrinsic scintillation
effect.
Description:
File table1.dat contains the flux density and measurement errors of
S5 0716+714 at the K-band and the Q-band over 4 epochs.
Objects:
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RA (2000) DE Designation(s)
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07 21 53.45 +71 20 36.4 S5 0716+714 = JVAS J0721+713
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 29 603 Flux density and error of S5 0716+714
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See also:
J/A+A/327/61 : BV(RI)c photometry of S5 0716+714 (Ghisellini+ 1997)
J/A+A/402/151 : S5 0716+714 UBVRI photometry (Raiteri+, 2003)
J/AJ/129/1818 : Photometry of S5 0716+714 (Wu+, 2005)
J/A+A/451/435 : BV(RI)c photometry of S5 0716+714 (Montagni+, 2006)
J/AJ/133/1599 : B'V'R' photometry of S5 0716+714 (Wu+, 2007)
J/AJ/136/1846 : BVRI light curves of S5 0716+714 (Zhang+, 2008)
J/ApJS/185/511 : Optical microvariability of S5 0716+714 (Poon+, 2009)
J/AZh/83/310 : BV(RI)c photometry of S5 0716+714 (Amirkhanyan+, 2006)
J/AJ/143/108 : B'V'R' photometry of the BL Lac object S5 0716+714 (Wu+, 2012)
J/A+A/558/A92 : S5 0716+714 microvariability observation (Bhatta+, 2013)
J/ApJ/783/83 : BVRI photometry of S5 0716+714 (Liao+, 2014)
J/ApJS/218/18 : 2004-2012 BVRI observations of blazar S5 0716+714 (Dai+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d MJD Modified Julian Date
11- 14 F4.2 Jy SK Flux density at K-band (22GHz)
16- 19 F4.2 Jy e_SK Measurement flux density error at K-band
21- 24 F4.2 Jy SQ Flux density at Q-band (43GHz)
26- 29 F4.2 Jy e_SQ Measurement flux density error at Q-band
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Acknowledgements:
Jee Won Lee, jeewon78(at)gmail.com
KASI/Kyung Hee University, Republic of Korea
(End) J.W. Lee [KASI/Kyung Hee Univ., Korea], P. Vannier [CDS] 04-Mar-2017