Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
권호 표지
DOI QR코드

DOI QR Code

SOURCE-FREQUENCY PHASE-REFERENCING OBSERVATION OF AGNS WITH KAVA USING SIMULTANEOUS DUAL-FREQUENCY RECEIVING

  • Zhao, Guang-Yao (Korea Astronomy and Space Science Institute) ;
  • Jung, Taehyun (Korea Astronomy and Space Science Institute) ;
  • Sohn, Bong Won (Korea Astronomy and Space Science Institute) ;
  • Kino, Motoki (Kogakuin University, Academic Support Center) ;
  • Honma, Mareki (National Astronomical Observatory of Japan) ;
  • Dodson, Richard (ICRAR, M468, University of Western Australia) ;
  • Rioja, Maria (ICRAR, M468, University of Western Australia) ;
  • Han, Seog-Tae (Korea Astronomy and Space Science Institute) ;
  • Shibata, Katsunori (National Astronomical Observatory of Japan) ;
  • Byun, Do-Young (Korea Astronomy and Space Science Institute) ;
  • Akiyama, Kazunori (Massachusetts Institute of Technology, Haystack Observatory) ;
  • Algaba, Juan-Carlos (Department of Physics and Astronomy, Seoul National University) ;
  • An, Tao (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Cheng, Xiaopeng (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Cho, Ilje (Korea Astronomy and Space Science Institute) ;
  • Cui, Yuzhu (National Astronomical Observatory of Japan) ;
  • Hada, Kazuhiro (National Astronomical Observatory of Japan) ;
  • Hodgson, Jeffrey A. (Korea Astronomy and Space Science Institute) ;
  • Jiang, Wu (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Lee, Jee Won (Korea Astronomy and Space Science Institute) ;
  • Lee, Jeong Ae (Department of Physics and Astronomy, Seoul National University) ;
  • Niinuma, Kotaro (Graduate School of Sciences and Technology for Innovation, Yamaguchi University) ;
  • Park, Jong-Ho (Department of Physics and Astronomy, Seoul National University) ;
  • Ro, Hyunwook (Department of Astronomy, Yonsei University) ;
  • Sawada-Satoh, Satoko (Graduate School of Science and Engineering, Kagoshima University) ;
  • Shen, Zhi-Qiang (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Tazaki, Fumie (National Astronomical Observatory of Japan) ;
  • Trippe, Sascha (Department of Physics and Astronomy, Seoul National University) ;
  • Wajima, Kiyoaki (Korea Astronomy and Space Science Institute) ;
  • Zhang, Yingkang (Shanghai Astronomical Observatory, Chinese Academy of Sciences)
  • Received : 2018.08.06
  • Accepted : 2019.01.23
  • Published : 2019.02.28
Download PDF
⟨ Previous Next ⟩

Abstract

The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implement compatible optics systems. Simultaneous dual/multi-frequency VLBI observations at mm wavelengths with international baselines are thus possible. In this paper, we present the results from the first successful simultaneous 22/43 GHz dual-frequency observation with KaVA(KVN and VERA array), including images and astrometric results. Our analysis shows that the newly implemented simultaneous receiving system has brought a significant extension of the coherence time of the 43 GHz visibility phases along the international baselines. The astrometric results obtained with KaVA are consistent with those obtained with the independent analysis of the KVN data. Our results thus confirm the good performance of the simultaneous receiving systems for the nonKVN stations. Future simultaneous observations with more global stations bring even higher sensitivity and micro-arcsecond level astrometric measurements of the targets.

Keywords

CMHHBA_2019_v52n1_23_f0001.tif 이미지

Figure 1. Self-calibrated images of 4C 39.25 (left) and 0945+408 (right) at 22 (upper) and 43 GHz (lower). The beams are shown in the lower left corner. The contour levels start from 3 times the r.m.s level and increase by a factor of 2.

CMHHBA_2019_v52n1_23_f0002.tif 이미지

Figure 2. visibility phases of 4C 39.25 along MIZ baselines at 43 GHz before (dots) and after (crosses) applying FPT from 22 GHz; Each point on the plot corresponds to a temporal average of 10 seconds.

CMHHBA_2019_v52n1_23_f0003.tif 이미지

Figure 3. Fractional flux recovery as functions of solution intervals for phase self-calibration, for the visibility phases before (dot-dashed line) and after (dashed line) applying FPT. The coherence time corresponds to a fractional flux recovery of 0.6.

CMHHBA_2019_v52n1_23_f0004.tif 이미지

Figure 4. SFPRed visibility phases of 0945+408 on all baselines at 43 GHz with a temporal average of 60s. The numbers in the parentheses in each panel correspond to the station codes of each antenna used by the correlator.

CMHHBA_2019_v52n1_23_f0005.tif 이미지

Figure 5. KaVA SFPRed map of 0945+408 at 43 GHz. The beam is 1.28 × 0.70 mas with a position angle of −71°. The grid serves as a visual guide for the offset of the peak of brightness from the center of the map.

CMHHBA_2019_v52n1_23_f0006.tif 이미지

Figure 6. Comparison of astrometric results from the SFPR analysis on the KaVA (squares) and KVN (circles) data with point source models (open symbols), structural models in Section 3.1 (half-filled symbols), and structual models from Niinuma et al. 2014 for 4C 39.25 (filled symbols).

References

  1. Algaba, J.-C., Zhao, G.-Y., Lee, S.-S., et al. 2015, Interferometric Monitoring of Gamma-Ray Bright Active Galactic Nuclei II: Frequency Phase Transfer, JKAS, 48, 237
  2. Beasley, A. J., & Conway, J. E. 1995, VLBI Phase-Referencing, Very Long Baseline Interferometry and the VLBA, 82, 327
  3. Blandford, R. D., & Konigl, A. 1979, Relativistic Jets as Compact Radio Sources, ApJ, 232, 34 https://doi.org/10.1086/157262
  4. Dodson, R., Rioja, M. J., Jung, T., et al. 2014, Astrometrically Registered Simultaneous Observations of the 22 GHz $H_2O$ and 43 GHz SiO Masers toward R Leonis Minoris Using KVN and Source/Frequency Phase Referencing, AJ, 148, 97 https://doi.org/10.1088/0004-6256/148/5/97
  5. Dodson, R., Rioja, M. J., Jung, T., et al. 2017, The Science Case for Simultaneous mm-Wavelength Receivers in Radio Astronomy, NewAR, 79, 85 https://doi.org/10.1016/j.newar.2017.09.003
  6. Dodson, R., Rioja, M., Bujarrabal, V., et al. 2018, Registration of $H_2O$ and SiO Masers in the Calabash Nebula to Confirm the Planetary Nebula Paradigm, MNRAS, 476, 520 https://doi.org/10.1093/mnras/sty239
  7. Han, S.-T., Lee, J.-W., Kang, J., et al. 2008, Millimeter-Wave Receiver Optics for Korean VLBI Network, IJIMW, 29, 69
  8. Han, S.-T., Lee, J.-W., Kang, J., et al. 2013, Korean VLBI Network Receiver Optics for Simultaneous Multifrequency Observation: Evaluation, PASP, 125, 539 https://doi.org/10.1086/671125
  9. Jiang, W., Shen, Z., Jiang, D., et al. 2018, VLBI Imaging of M81* at $\lambda$ = 3.4 mm with Source-Frequency Phase-Referencing, ApJL, 853, 14 https://doi.org/10.3847/1538-4357/aa93df
  10. Jung, T., Sohn, B. W., Kobayashi, H., et al. 2011, First Simultaneous Dual-Frequency Phase Referencing VLBI Observation with VERA, PASJ, 63, 375 https://doi.org/10.1093/pasj/63.2.375
  11. Jung, T., Dodson, R., Han, S.-T., et al. 2015, Measuring the Core Shift Effect in AGN Jets with the Extended Korean VLBI Network, JKAS, 48, 277
  12. Jung, T., et al. 2019, JKAS, in preperation.
  13. Kino, M., Niinuma, K., Zhao, G.-Y., et al. 2015, Key Science Observations of AGNs with KaVA Array, PKAS, 30, 633
  14. Lee, S.-S., Oh, C. S., Roh, D. G., et al. 2015a, A New Hardware Correlator in Korea: Performance Evaluation Using KVN Observations, JKAS, 48, 125
  15. Lee, S.-S., Byun, D.-Y., Oh, C. S., et al. 2015b, Amplitude Correction Factors of Korean VLBI Network Observations, JKAS, 48, 229
  16. Lister, M. L., Aller, M. F., Aller, H. D., et al. 2013, MOJAVE. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei, AJ, 146, 120 https://doi.org/10.1088/0004-6256/146/5/120
  17. Middelberg, E., Roy, A. L., Walker, R. C., & Falcke, H. 2005, VLBI Observations ofWeak Sources Using Fast Frequency Switching, A&A, 433, 897 https://doi.org/10.1051/0004-6361:20042078
  18. Niinuma, K., Lee, S.-S., Kino, M., et al. 2014, VLBI Observations of Bright AGN Jets with the KVN and VERA Array (KaVA): Evaluation of Imaging Capability, PASJ 66, 103 https://doi.org/10.1093/pasj/psu104
  19. Rioja, M., & Dodson, R. 2011, High-Precision Astrometric Millimeter Very Long Baseline Interferometry Using a New Method for Atmospheric Calibration, AJ, 141, 114 https://doi.org/10.1088/0004-6256/141/4/114
  20. Rioja, M., Dodson, R., Asaki, Y., et al. 2012, The Impact of Frequency Standards on Coherence in VLBI at the Highest Frequencies, AJ, 144, 121 https://doi.org/10.1088/0004-6256/144/4/121
  21. Rioja, M., Dodson, R., Jung, T. H., et al., 2014, Verification of the Astrometric Performance of the Korean VLBI Network, Using Comparative SFPR Studies with the VLBA at 14/7 mm, AJ, 148, 84 https://doi.org/10.1088/0004-6256/148/5/84
  22. Rioja, M. J., Dodson, R., Jung, T., & Sohn, B. W. 2015, The Power of Simultaneous Multifrequency Observations for mm-VLBI: Astrometry up to 130 GHz with the KVN, AJ, 150, 202 https://doi.org/10.1088/0004-6256/150/6/202
  23. Yoon, D.-H., Cho, S.-H., Yun, Y., et al. 2018, Astrometrically Registered Maps of $H_2O$ and SiO Masers toward VX Sagittarii, Nature Communications, 9, 2534 https://doi.org/10.1038/s41467-018-04767-8
  24. Zhao, G.-Y., Algaba, J. C., Lee, S. S., et al. 2018, The Power of Simultaneous Multi-Frequency Observations for mm-VLBI: Beyond Frequency Phase Transfer, AJ, 155, 26
  25. Zhao, G.-Y., Jung, T., Dodson, R., Rioja, M., & Sohn, B. W. 2015, KVN Source-Frequency Phase-Referencing Observation of 3c 66A and 3c 66B, PKAS, 30, 629