Recent Papers using KVN


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  • 산업용 이더넷 기반 VLBI 수신기 M&C 구현에 관한 연구 (A Study on the implementation of VLBI receiver M&C based on Industrial Ethernet)    2024-12

    Publication:
    한국전자통신학회논문지(Journal Of The Korea Institute Of Electronic Communication Sciences) 19, 6호
    Authors:
    Affiliation:
    Abstract:
    The Korea Astronomy and Space Science Institute is currently carrying out the EKVN(Extended Korean VLBI Network) project to construct a 21m radio telescope and supporting VLBI(Very Long Baseline Interferometer) research facilities on the Seoul National University Pyeongchang campus as the fourth site of the KVN to improve VLBI observation performance from 2020. Through this, it is expected that the observation of astronomical radio sources that has not been seen until now will be possible, and international collaborative research of KVN will be activated through participation in the EHT (Event Horizon Telescope) consortium. With the construction of the radio telescope completed in the second half of last year, the KVN Seoul National University Pyeongchang Radio Astronomy Observatory is currently in the final stages of installing a wideband receiver that simultaneously receives multi-wavelength astronomical radio signals, a direct sampler that converts analog data into high speed digital data, and a computing system that stores and analyzes observation data. In this paper, we will focus on the wideband VLBI receiver and discuss an efficient Monitor & Control implementation method. To this end, we will describe a method to utilize Profinet, which is one of the representative technologies of industrial Ethernet and has been adopted in various field of industries such as automobiles, energy, and chemistry, and to apply it efficiently to the field of scientific research.
    Link:
    Attache file:

  • Long-Term Simultaneous Monitoring Observations of SiO and H2O Masers Toward the Mira Variable WX Serpentis    2024-12

    Publication:
    Astrophysical Journal Supplement Series
    Authors:
    Lim, J-H. 1, 2, Kim, J. 1, Cho, S. 4, Kim, H. 1, Yoon, D.-H. 1, Son, S.-M. 2 and Suh, K.-W. 2
    Affiliation:
    1 Radio Astronomy Division, Korea Astronomy and Space Science Institute
    Yuseong–gu, Daejeon 34055, Republic of Korea
    2 Department of Astronomy and Space Science, Chungbuk National University
    Cheongju, 28644, Republic of Korea
    3 Seoul National University
    Gwanak-gu, Seoul 08826, Republic of Korea
    Abstract:
    We present the results from long-term simultaneous monitoring observations of SiO and H2O masers toward the Mira variable star WX Serpentis. This study has been conducted with 21 m single-dish radio telescopes of the Korean VLBI Network from 2009 June to 2021 June. Five maser lines were considered: SiO v =1, 2, J =1?0; SiOv =1, J =2?1, 3?2; and H2O 61,6 ? 52,3 transitions, with the SiO maser lines distributed near the stellar velocity, and the H2O maser exhibiting an asymmetric line profile with 5 ? 6 peaked components. Intense H2O maser emissions suddenly appeared in 2019 September, indicating flaring. The intensity variations of SiO and H2O masers are strongly correlated with the optical light curve (OLC) of the central star, with individual phase lags; the phase lag of the H2O maser relative to the OLC is larger than that of the SiO masers. The consequent phase difference between the SiO masers and the H2O maser likely indicate that their formation regions and main driving mechanisms are different to each other. The SiO masers in WX Ser exhibit a dominant single peak velocity distribution, similar to other Mira variable stars. However, the H2O maser displays distinct morphological features, showing a radial acceleration and preferential intensity dominance at blueshifted velocities. This suggests that the H2O maser clouds of WX Ser are moving outward, thereby developing an asymmetric outflow owing to non-uniform material ejection from the stellar atmosphere. The findings confirm that an initial asymmetric outflow structure emerged during the thermally pulsing asymptotic giant branch phase, specifically in the Mira variable star stage.
    Link:
    DOI: 10.3847/1538-4365/ad7d80
    Attache file:

  • Magnetic field properties inside the jet of Mrk 421    2024-12

    Publication:
    Astronomy & Astrophysics
    Authors:
    Dawoon E. Kim, Laura Di Gesu, Ioannis Liodakis, Alan P. Marscher, Svetlana G. Jorstad, et al.
    Affiliation:
    Abstract:
    We aim to probe the magnetic field geometry and particle acceleration mechanism in the relativistic jets of supermassive black holes.
    Methods. We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measurements from 2022 December 6?8. During the IXPE observation, we also monitored Mrk 421 using Swift-XRT and obtained a single observation with XMM-Newton to improve the X-ray spectral analysis. The time-averaged X-ray polarization was determined consistently using the event-by-event Stokes parameter analysis, spectropolarimetric fit, and maximum likelihood methods.
    We examined the polarization variability over both time and energy, the former via analysis of IXPE data obtained over a time span of 7 months.
    Results. We detected X-ray polarization of Mrk 421 with a degree of ΠX=14±1% and an electric-vector position angle ψX=107±3? in the 2?8 keV band. From the time variability analysis, we find a significant episodic variation in ψX. During the 7 months from the first IXPE pointing of Mrk 421 in 2022 May, ψX varied in the range 0? to 180?, while ΠX remained relatively constant within ∼10?15%. Furthermore, a swing in ψX in 2022 June was accompanied by simultaneous spectral variations. The results of the multiwavelength polarimetry show that ΠX was generally ∼2?3 times greater than Π at longer wavelengths, while ψ fluctuated. Additionally, based on radio, infrared, and optical polarimetry, we find that the rotation of ψ occurred in the opposite direction with respect to the rotation of ψX and over longer timescales at similar epochs.
    Conclusions. The polarization behavior observed across multiple wavelengths is consistent with previous IXPE findings for HSP blazars. This result favors the energy-stratified shock model developed to explain variable emission in relativistic jets.We considered two versions of the model, one with linear and the other with radial stratification geometry, to explain the rotation of ψX. The accompanying spectral variation during the ψX rotation can be explained by a fluctuation in the physical conditions, for example in the energy distribution of relativistic electrons. The opposite rotation direction of ψ between the X-ray and longer wavelength polarization accentuates the conclusion that the X-ray emitting region is spatially separated from that at longer wavelengths. Moreover, we identify a highly polarized knot of radio emission moving down the parsec-scale jet during the episode of ψX rotation, although it is unclear whether there is any connection between the two events.
    Link:
    DOI 10.1051/0004-6361/202347408
    Attache file:

  • X-Ray and Multiwavelength Polarization of Mrk 501 from 2022 to 2023    2024-10

    Publication:
    ASTROPHYSICAL JOURNAL 974, 1, 974-950
    Authors:
    Chien-Ting J. Chen 1,2 , Ioannis Liodakis 3,4 , Riccardo Middei 5,6 , Dawoon E. Kim 7,8,9 , Laura Di Gesu 10 ,
    Alessandro Di Marco 7 , Steven R. Ehlert 3 , Manel Errando 11 , Michela Negro 12 , Svetlana G. Jorstad 13,14 ,
    Alan P. Marscher 13 , Kinwah Wu 15 , Iván Agudo 16 , Juri Poutanen 17 , Tsunefumi Mizuno 18 , Pouya M. Kouch 17,19,20 ,
    Elina Lindfors 17 , George A. Borman 21 , Tatiana S. Grishina 14 , Evgenia N. Kopatskaya 14 , Elena G. Larionova 14 ,
    Daria A. Morozova 14 , Sergey S. Savchenko 14,22 , Ivan S. Troitsky 14 , Yulia V. Troitskaya 14 , Andrey A. Vasilyev 14 ,
    Alexey V. Zhovtan 21 , Francisco José Aceituno 23 , Giacomo Bonnoli 23,24 , Víctor Casanova 23 , Juan Escudero 23 ,
    Beatriz Agís-González 4,23 , César Husillos 25 , Jorge Otero Santos 23 , Alfredo Sota 23 , Vilppu Piirola 17 , Ioannis Myserlis 26,27 ,
    Emmanouil Angelakis 28 , Alexander Kraus 27 , Mark Gurwell 29 , Garrett Keating 29 , Ramprasad Rao 29 , Sincheol Kang 30 ,
    Sang-Sung Lee 30,31 , Sang-Hyun Kim 30,31 , Whee Yeon Cheong 30,31 , Hyeon-Woo Jeong 30,31 , Chanwoo Song 30,31 ,
    Andrei V. Berdyugin 17 , Masato Kagitani 32 , Vadim Kravtsov 17 , Anagha P. Nitindala 17 , Takeshi Sakanoi 32 ,
    Ryo Imazawa 33 , Mahito Sasada 34 , Yasushi Fukazawa 33,35,36 , Koji S. Kawabata 33,35,36 , Makoto Uemura 33,35,36 ,
    Tatsuya Nakaoka 35 , Hiroshi Akitaya 37 , Carolina Casadio 38,39 , Albrecht Sievers 26 , Lucio Angelo Antonelli 5,40 ,
    Matteo Bachetti 41 , Luca Baldini 42,43 , Wayne H. Baumgartner 3 , Ronaldo Bellazzini 42 , Stefano Bianchi 44 ,
    Stephen D. Bongiorno 3 , Raffaella Bonino 45,46 , Alessandro Brez 42 , Niccoló Bucciantini 47,48,49 , Fiamma Capitanio 7 ,
    Simone Castellano 42 , Elisabetta Cavazzuti 10 , Stefano Ciprini 5,50 , Enrico Costa 7 , Alessandra De Rosa 7 ,
    Ettore Del Monte 7 , Niccoló Di Lalla 51 , Immacolata Donnarumma 10 , Victor Doroshenko 52 , Michal Dovčiak 53 ,
    Teruaki Enoto 54 , Yuri Evangelista 55 , Sergio Fabiani 7 , Riccardo Ferrazzoli 7 , Javier A. Garcia 56 , Shuichi Gunji 57 ,
    Kiyoshi Hayashida 58 , Jeremy Heyl 59 , Wataru Iwakiri 60 , Philip Kaaret 3 , Vladimir Karas 53 , Fabian Kislat 61 ,
    Takao Kitaguchi 54 , Jeffery J. Kolodziejczak 3 , Henric Krawczynski 11 , Fabio La Monaca 7,62,63 , Luca Latronico 45 ,
    Simone Maldera 45 , Alberto Manfreda 64 , Frédéric Marin 65 , Andrea Marinucci 10 , Herman L. Marshall 66 ,
    Francesco Massaro 45,46 , Giorgio Matt 44 , Ikuyuki Mitsuishi 67 , Fabio Muleri 7 , C.-Y. Ng 68 , Stephen L. O’Dell 3 ,
    Nicola Omodei 51 , Chiara Oppedisano 45 , Alessandro Papitto 40 , George G. Pavlov 69 , Abel Lawrence Peirson 51 ,
    Matteo Perri 5,40 , Melissa Pesce-Rollins 42 , Pierre-Olivier Petrucci 70 , Maura Pilia 41 , Andrea Possenti 41 ,
    Simonetta Puccetti 5 , Brian D. Ramsey 3 , John Rankin 7 , Ajay Ratheesh 7 , Oliver J. Roberts 1 , Roger W. Romani 51 ,
    Carmelo Sgró 42 , Patrick Slane 71 , Paolo Soffitta 7 , Gloria Spandre 42 , Douglas A. Swartz 1 , Toru Tamagawa 54 ,
    Fabrizio Tavecchio 24 , Roberto Taverna 72 , Yuzuru Tawara 67 , Allyn F. Tennant 3 , Nicholas E. Thomas 3 ,
    Francesco Tombesi 50,62 , Alessio Trois 41 , Sergey S. Tsygankov 17 , Roberto Turolla 15,72 , Jacco Vink 73 ,
    Martin C. Weisskopf 3 , Fei Xie 7,74 , and Silvia Zane 15
    Affiliation:
    1 Science and Technology Institute, Universities Space Research Association, Huntsville, AL 35805, USA
    2
    Astrophysics Office, NASA Marshall Space Flight Center, ST12, Huntsville, AL 35812, USA
    3
    NASA Marshall Space Flight Center, Huntsville, AL 35812, USA
    4
    Institute of Astrophysics, Foundation for Research and Technology-Hellas, GR-70013 Heraklion, Greece
    5
    Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
    6
    INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
    7
    INAF Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
    8
    Dipartimento di Fisica, Università degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
    9
    Dipartimento di Fisica, Università degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    10
    ASI - Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
    11
    Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA
    12
    Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
    13
    Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
    14
    Saint Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia
    15
    Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
    16
    Instituto de Astrofísica de Andalucía–CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
    17
    Department of Physics and Astronomy, 20014 University of Turku, Finland
    18
    Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    19
    Finnish Centre for Astronomy with ESO, 20014 University of Turku, Finland
    20
    Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
    21
    Crimean Astrophysical Observatory RAS, P/O Nauchny, 298409, Crimea †
    22
    Pulkovo Observatory, St. Petersburg, 196140, Russia
    23
    Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
    24
    INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
    25
    Geological and Mining Institute of Spain (IGME-CSIC), Calle Ríos Rosas 23, E-28003, Madrid, Spain
    26
    Institut de Radioastronomie Millimétrique, Avenida Divina Pastora, 7, Local 20, E-18012 Granada, Spain
    27
    Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
    28
    Section of Astrophysics, Astronomy & Mechanics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografos 15784,
    Greece
    29
    Center for Astrophysics—Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
    30
    Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea
    31
    University of Science and Technology, Korea, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
    32
    Graduate School of Sciences, Tohoku University, Aoba-ku, 980-8578 Sendai, Japan
    33
    Department of Physics, Graduate School of Advanced Science and Engineering, Hiroshima University Kagamiyama, 1-3-1 Higashi-Hiroshima, Hiroshima 739-8526, Japan
    1The Astrophysical Journal, 974:50 (16pp), 2024 October 10
    Chen et al.
    34
    Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
    Hiroshima Astrophysical Science Center, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    36
    Core Research for Energetic Universe (Core-U), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    37
    Astronomy Research Center, Chiba Institute of Technology 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
    38
    Institute of Astrophysics, Foundation for Research and Technology - Hellas, Voutes, 7110 Heraklion, Greece
    39
    Department of Physics, University of Crete, 70013, Heraklion, Greece
    40
    INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (RM), Italy
    41
    INAF Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
    42
    Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
    43
    Dipartimento di Fisica, Universitá di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
    44
    Dipartimento di Matematica e Fisica, Universitá degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
    45
    Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
    46
    Dipartimento di Fisica, Universitá degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
    47
    INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
    48
    Dipartimento di Fisica e Astronomia, Universitá degli Studi di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
    49
    Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
    50
    Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    51
    Department of Physics and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California 94305, USA
    52
    Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
    53
    Astronomical Institute of the Czech Academy of Sciences, Boční II 1401/1, 14100 Praha 4, Czech Republic
    54
    RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
    55
    f, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
    56
    NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
    57
    Yamagata University,1-4-12 Kojirakawa-machi, Yamagata-shi 990-8560, Japan
    58
    Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
    59
    University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    60
    International Center for Hadron Astrophysics, Chiba University, Chiba 263-8522, Japan
    61
    Department of Physics and Astronomy and Space Science Center, University of New Hampshire, Durham, NH 03824, USA
    62
    Dipartimento di Fisica, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    63
    Dipartimento di Fisica, Universitá degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
    64
    Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Strada Comunale Cinthia, 80126 Napoli, Italy
    65
    Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
    66
    MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
    67
    Graduate School of Science, Division of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
    68
    Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong
    69
    Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA
    70
    Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
    71
    Center for Astrophysics—Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138, USA
    72
    Dipartimento di Fisica e Astronomia, Universitá degli Studi di Padova, Via Marzolo 8, 35131 Padova, Italy
    73
    Anton Pannekoek Institute for Astronomy & GRAPPA, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
    74
    Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, Peopleʼs Republic of
    China
    Abstract:
    We present multiwavelength polarization measurements of the luminous blazar Mrk 501 over a 14 month period.
    The 2?8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE)with six
    100 ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by
    simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical?infrared
    polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization
    measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant
    variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at >3σabove the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE
    observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization
    degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario
    proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission
    arises from different regions.
    Link:
    10.3847/1538-4357/ad63a1
    Attache file:

  • Discovery of Limb Brightening in the Parsec-scale Jet of NGC 315 through Global Very Long Baseline Interferometry Observations and Its Implications for Jet Models    2024-10

    Publication:
    The Astrophysical Journal Letters, 973, L45
    Authors:
    Jongho Park 1,2 , Guang-Yao Zhao 3 , Masanori Nakamura 4,2 , Yosuke Mizuno 5,6 , Hung-Yi Pu 7,8 , Keiichi Asada 4 ,
    Kazuya Takahashi 9 , Kenji Toma 10,11 , Motoki Kino 12,13 , Ilje Cho 14,15,16 , Kazuhiro Hada 17,18 , Phil G. Edwards 19 ,
    Hyunwook Ro 14 , Minchul Kam 20 , Kunwoo Yi 20 , Yunjeong Lee 21 , Shoko Koyama 22,4 , Do-Young Byun 14,23 ,
    Chris Phillips 19 , Cormac Reynolds 24 , Jeffrey A. Hodgson 25 , and Sang-Sung Lee 14,23
    Affiliation:
    1 School of Space Research, Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea; jparkastro@khu.ac.kr
    2
    Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, R.O.C.
    3
    Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
    4
    Department of General Science and Education, National Institute of Technology, Hachinohe College, 16-1 Uwanotai, Tamonoki, Hachinohe, Aomori 039-1192,
    Japan
    5
    Tsung-Dao Lee Institute, Shanghai Jiao Tong University, 520 Shengrong Road, Shanghai, 201210, Peopleʼs Republic of China
    6
    School of Physics & Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, Peopleʼs Republic of China
    7
    Department of Physics, National Taiwan Normal University, No. 88, Section 4, Tingzhou Road, Taipei 116, Taiwan, R.O.C.
    8
    Centre of Astronomy and Gravitation, National Taiwan Normal University, No. 88, Section 4, Tingzhou Road, Taipei 116, Taiwan, R.O.C.
    9
    Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
    10
    Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
    11
    Astronomical Institute, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
    12
    Kogakuin University of Technology & Engineering, Academic Support Center, 2665-1 Nakano-machi, Hachioji, Tokyo 192-0015, Japan
    13
    National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
    14
    Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
    15
    Department of Astronomy, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 03722, Republic of Korea
    16
    Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain
    17
    Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, 467-8501, Aichi, Japan
    18
    Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka-cho, Mizusawa, Oshu, 023-0861, Iwate, Japan
    19
    CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, Australia
    20
    Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
    21
    Department of Astronomy and Space Science, Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea
    22
    Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
    23
    University of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea
    24
    CSIRO, Space and Astronomy, PO Box 1130, Bentley, WA 6151, Australia
    25
    Department of Physics and Astronomy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
    Abstract:
    We report the first observation of the nearby giant radio galaxy NGC 315 using a global very long baseline interferometry (VLBI) array consisting of 22 radio antennas located across five continents, including high-sensitivity stations, at 22 GHz. Utilizing the extensive u v-coverage provided by the array, coupled with the application of a recently developed superresolution imaging technique based on the regularized maximum-likelihood method, we were able to transversely resolve the NGC 315 jet at parsec scales for the first time. Previously known for its central ridge-brightened morphology at similar scales in former VLBI studies, the jet now clearly exhibits a limb-brightened structure. This finding suggests an inherent limb brightening that was not observable before due to limited angular resolution. Considering that the jet is viewed at an angle of ∼50°, the observed limb brightening is challenging to reconcile with the magnetohydrodynamic models and simulations, which predict that the Doppler-boosted jet edges should dominate over the nonboosted central layer. The conventional jet model that proposes a fast spine and a slow sheath with uniform transverse emissivity may pertain to our observations. However, in this model, the relativistic spine would need to travel at speeds of Γ ? 6.0?12.9 along the deprojected jet distance of (2.3?10.8) × 103 gravitational radii from the black hole. We propose an alternative scenario that suggests higher emissivity at the jet boundary layer, resulting from more efficient particle acceleration or mass loading onto the jet edges, and consider prospects for future observations with even higher angular resolution.
    Link:
    10.3847/2041-8213/ad7137
    Attache file:

  • Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-Ray Polarimetry Explorer    2024-09

    Publication:
    ASTROPHYSICAL JOURNAL 972, 1, 74-92
    Authors:
    Herman L. Marshall 1 , Ioannis Liodakis 2,3 , Alan P. Marscher 4 , Niccolò Di Lalla 5 , Svetlana G. Jorstad 4,6 ,
    Dawoon E. Kim 7,8,9 , Riccardo Middei 10,11 , Michela Negro 12 , Nicola Omodei 5 , Abel L. Peirson 5 , Matteo Perri 10,13 ,
    Simonetta Puccetti 10 , Marco Laurenti 10 , Iván Agudo 14 , Giacomo Bonnoli 14,15 , Andrei V. Berdyugin 16 ,
    Elisabetta Cavazzuti 17 , Nicole Rodriguez Cavero 18 , Immacolata Donnarumma 17 , Laura Di Gesu 17 ,
    Jenni Jormanainen 16,19 , Henric Krawczynski 18 , Elina Lindfors 16,19 , Greg Madjeski 20 , Frédéric Marin 21 ,
    Francesco Massaro 22,23 , Luigi Pacciani 7 , Juri Poutanen 16 , Fabrizio Tavecchio 15 , Pouya M. Kouch 16,19 ,
    Francisco José Aceituno 14 , Maria I. Bernardos 14 , Víctor Casanova 14 , Maya García-Comas 14 , Beatriz Agís-González 3,14 ,
    César Husillos 14 , Alessandro Marchini 24 , Alfredo Sota 14 , Dmitry Blinov 3,25 , Ioakeim G. Bourbah 25 ,
    Sebastian Kielhmann 3,25 , Evangelos Kontopodis 25 , Nikos Mandarakas 25,26 , Stylianos Romanopoulos 25,27 , Raphael Skalidis 25,26 ,
    Anna Vervelaki 25 , George A. Borman 28 , Evgenia N. Kopatskaya 6 , Elena G. Larionova 6 , Daria A. Morozova 6 ,
    Sergey S. Savchenko 6,29,30 , Andrey A. Vasilyev 6 , Alexey V. Zhovtan 28 , Carolina Casadio 25,26 , Juan Escudero 31 ,
    Joana Kramer 32 , Ioannis Myserlis 33,34 , Efthalia Trainou 35 , Ryo Imazawa 36 , Mahito Sasada 37 , Yasushi Fukazawa 36,38,39 ,
    Koji S. Kawabata 36,38,39 , Makoto Uemura 36,38,39 , Tsunefumi Mizuno 38 , Tatsuya Nakaoka 38 , Hiroshi Akitaya 40 ,
    Joseph R. Masiero 41 , Dimitri Mawet 41 , Georgia V. Panopoulou 41 , Samaporn Tinyanont 42 , Masato Kagitani 43 ,
    Vadim Kravtsov 16 , Takeshi Sakanoi 43 , Matthew Dattolo 44 , Mark Gurwell 45 , Garrett Keating 45 , Ramprasad Rao 45 ,
    Whee Yeon Cheong 46,47 , Hyeon-Woo Jeong 46,47 , Sincheol Kang 46 , Sang-Hyun Kim 46,47 , Sang-Sung Lee 46,47 ,
    Emmanouil Angelakis 48 , Alexander Kraus 34 , Antonio Hales 49,50 , Seiji Kameno 51,52 , Ruediger Kneissl 53,54 , Hugo Messias 49 ,
    Hiroshi Nagai 55,56 , Lucio A. Antonelli 10,13 , Matteo Bachetti 57 , Luca Baldini 58,59 , Wayne H. Baumgartner 2 ,
    Ronaldo Bellazzini 58 , Stefano Bianchi 60 , Stephen D. Bongiorno 2 , Raffaella Bonino 22,61 , Alessandro Brez 58 ,
    Niccolò Bucciantini 62,63,64 , Fiamma Capitanio 7 , Simone Castellano 58 , Chen-Ting Chen 65 , Stefano Ciprini 10,66 ,
    Enrico Costa 7 , Alessandra De Rosa 7 , Ettore Del Monte 7 , Alessandro Di Marco 7 , Victor Doroshenko 67 ,
    Michal Dovčiak 68 , Steven R. Ehlert 2 , Teruaki Enoto 69 , Yuri Evangelista 7 , Sergio Fabiani 7 , Riccardo Ferrazzoli 7 ,
    Javier A. Garcia 41,70 , Shuichi Gunji 71 , Kiyoshi Hayashida 72 , Jeremy Heyl 73 , Wataru Iwakiri 74 , Philip Kaaret 2 ,
    Vladimir Karas 68 , Fabian Kislat 75 , Takao Kitaguchi 69 , Jeffery J. Kolodziejczak 2 , Fabio La Monaca 7 , Luca Latronico 22 ,
    Simone Maldera 22 , Alberto Manfreda 58 , Andrea Marinucci 17 , Giorgio Matt 60 , Ikuyuki Mitsuishi 76 , Fabio Muleri 7 ,
    C.-Y. Ng 77 , Stephen L. O’Dell 2 , Chiara Oppedisano 22 , Alessandro Papitto 13 , George G. Pavlov 78 ,
    Melissa Pesce-Rollins 58 , Pierre-Olivier Petrucci 79 , Maura Pilia 57 , Andrea Possenti 57 , Brian D. Ramsey 2 ,
    John Rankin 7 , Ajay Ratheesh 7 , Oliver J. Roberts 65 , Roger W. Romani 5 , Carmelo Sgrò 58 , Patrick Slane 45 ,
    Paolo Soffitta 7 , Gloria Spandre 58 , Douglas A. Swartz 65 , Toru Tamagawa 69 , Roberto Taverna 80 , Yuzuru Tawara 76 ,
    Allyn F. Tennant 2 , Nicholas E. Thomas 2 , Francesco Tombesi 9,66,81 , Alessio Trois 57 , Sergey S. Tsygankov 16 ,
    Roberto Turolla 80,82 , Jacco Vink 83 , Martin C. Weisskopf 2 , Kinwah Wu 82 , Fei Xie 7,84 , and Silvia Zane 82
    Affiliation:
    1 MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA;
    hermanm@mit.edu
    2
    NASA Marshall Space Flight Center, Huntsville, AL 35812, USA
    3
    Institute of Astrophysics, Foundation for Research and Technology-Hellas, GR-70013 Heraklion, Greece
    4
    Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
    5
    Department of Physics and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA
    6
    Saint Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia
    7
    INAF Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
    8
    Dipartimento di Fisica, Università degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
    9
    Dipartimento di Fisica, Università degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    10
    Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
    11
    INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
    12
    Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
    13
    INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (RM), Italy
    14
    Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E–18080 Granada, Spain
    15
    INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I–23807 Merate, Italy
    16
    Department of Physics and Astronomy, 20014 University of Turku, Finland
    17
    Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
    18
    Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA
    19
    Finnish Centre for Astronomy with ESO, University of Turku, 20014, Finland
    20
    KIPAC and SLAC, Stanford University, Stanford, CA, 94305, USA
    21
    Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
    22
    Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
    23
    Dipartimento di Fisica, Universitá degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
    24
    Department of Physical Sciences, Earth and Environment, Astronomical Observatory , University of Siena, Via Roma 56, 53100 Siena, Italy
    25
    Department of Physics, University of Crete, 70013, Heraklion, Greece
    26
    Institute of Astrophysics, Foundation for Research and Technology-Hellas, 71110 Heraklion, Greece
    27
    Institute of Astrophysics, Voutes, 7110, Heraklion, Greece
    1The Astrophysical Journal, 972:74 (19pp), 2024 September 1
    Marshall et al.
    28
    85
    Crimean Astrophysical Observatory RAS, P/O Nauchny, 298409, Crimea
    Special Astrophysical Observatory, Russian Academy of Sciences, 369167, Nizhnii Arkhyz, Russia
    30
    Pulkovo Observatory, 196140 St. Petersburg, Russia
    31
    Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, 18008, Granada, Spain
    32
    Max Planck Institute for Radio Astronomy, Auf dem Huegel 69, Bonn, Germany
    33
    Institut de Radioastronomie Millimétrique, Avenida Divina Pastora, 7, Local 20, E-18012 Granada, Spain
    34
    Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
    35
    Instituto de Astrofísicade Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
    36
    Department of Physics, Graduate School of Advanced Science and Engineering, Hiroshima University Kagamiyama, 1-3-1 Higashi-Hiroshima, Hiroshima 739-
    8526, Japan
    37
    Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
    38
    Hiroshima Astrophysical Science Center, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    39
    Core Research for Energetic Universe (Core-U), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    40
    Planetary Exploration Research Center, Chiba Institute of Technology 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
    41
    California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
    42
    University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
    43
    Graduate School of Sciences, Tohoku University, Aoba-ku, 980-8578 Sendai, Japan
    44
    Astronomy Department, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
    45
    Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
    46
    Korea Astronomy & Space Science Institute, Daedeokdae-ro 776,Yuseong-gu, Daejeon 34055, Republic of Korea
    47
    University of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea
    48
    Section of Astrophysics, Astronomy & Mechanics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografos 15784,
    Greece
    49
    Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura 763-0355, Santiago de Chile, Chile
    50
    National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
    51
    Joint ALMA Observatory, Alonso de Cordova 3107 Vitacura, Santiago 763-0355, Chile
    52
    NAOJ Chile Observatory, Alonso de Cordova 3788, Oficina 61B, Vitacura, Santiago, Chile
    53
    European Southern Observatory, ESO Vitacura, Alonso de Cordova 3107, Vitacura, Casilla, 19001 Santiago, Chile
    54
    Atacama Large Millimeter/submillimeter Array, ALMA Santiago Central Offices, Alonso de Cordova 3107, Vitacura, Casilla, 763-0355 Santiago, Chile
    55
    National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
    56
    Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
    57
    INAF Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
    58
    Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
    59
    Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
    60
    Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
    61
    Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
    62
    INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
    63
    Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
    64
    Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
    65
    Space and Technology Institute, Universities Space Research Association, Huntsville, AL 35805, USA
    66
    Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    67
    Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
    68
    Astronomical Institute of the Czech Academy of Sciences, Boční II 1401/1, 14100 Praha 4, Czech Republic
    69
    RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
    70
    NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
    71
    Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata-shi 990-8560, Japan
    72
    Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
    73
    University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
    74
    International Center for Hadron Astrophysics, Chiba University, Chiba, 263-8522, Japan
    75
    Department of Physics and Astronomy and Space Science Center, University of New Hampshire, Durham, NH 03824, USA
    76
    Graduate School of Science, Division of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
    77
    Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong
    78
    Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA
    79
    Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
    80
    Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Via Marzolo 8, 35131 Padova, Italy
    81
    Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
    82
    Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey, RH5 6NT, UK
    83
    Anton Pannekoek Institute for Astronomy & GRAPPA, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
    84
    Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, People’s Republic of
    China
    Abstract:
    We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE)of three low
    spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For
    none of these objects was IXPE able to detect X-ray polarization at the 3σlevel. However, we placed upper limits
    on the polarization degree at ∼10%?30%. The undetected polarizations favor models where the X-ray band is
    dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic
    models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our
    contemporaneous multiwavelength polarization campaigns.
    Link:
    Attache file:

  • IXPE observation of PKS 2155?304 reveals the most highly polarized blazar    2024-09

    Publication:
    Astronomy & Astrophysics, 689, A119
    Authors:
    Pouya M. Kouch 1,2,3,? , Ioannis Liodakis 4,5 , Riccardo Middei 9,10 , Dawoon E. Kim 6,7,8 , Fabrizio Tavecchio 12 ,
    Alan P. Marscher 13 , Herman L. Marshall 14 , Steven R. Ehlert 4 , Laura Di Gesu 37 , Svetlana G. Jorstad 13,50 ,
    Iván Agudo 28 , Grzegorz M. Madejski 41 , Roger W. Romani 40 , Manel Errando 52 , Elina Lindfors 1,2 ,
    Kari Nilsson 2 , Ella Toppari 1,2 , Stephen B. Potter 15,16 , Ryo Imazawa 17 , Mahito Sasada 19 , Yasushi Fukazawa 17,18,20 ,
    Koji S. Kawabata 17,18,20 , Makoto Uemura 17,18,20 , Tsunefumi Mizuno 17 , Tatsuya Nakaoka 18 , Hiroshi Akitaya 21 ,
    Callum McCall 66 , Helen E. Jermak 66 , Iain A. Steele 66 , Ioannis Myserlis 22,23 , Mark Gurwell 24 ,
    Garrett K. Keating 24 , Ramprasad Rao 24 , Sincheol Kang 25 , Sang-Sung Lee 25,26 , Sang-Hyun Kim 25,26 ,
    Whee Yeon Cheong 25,26 , Hyeon-Woo Jeong 25,26 , Emmanouil Angelakis 27 , Alexander Kraus 23 ,
    Francisco José Aceituno 28 , Giacomo Bonnoli 12,28 , Víctor Casanova 28 , Juan Escudero 28 ,
    Beatriz Agís-González 5,28 , César Husillos 28,67 , Daniel Morcuende 28 , Jorge Otero-Santos 28 , Alfredo Sota 28 ,
    Rumen Bachev 65 , Lucio Angelo Antonelli 9,10 , Matteo Bachetti 11 , Luca Baldini 29,30 , Wayne H. Baumgartner 4 ,
    Ronaldo Bellazzini 29 , Stefano Bianchi 31 , Stephen D. Bongiorno 4 , Raffaella Bonino 32,33 , Alessandro Brez 29 ,
    Niccolò Bucciantini 34,35,36 , Fiamma Capitanio 6 , Simone Castellano 29 , Elisabetta Cavazzuti 37 ,
    Chien-Ting Chen 38 , Stefano Ciprini 9,39 , Enrico Costa 6 , Alessandra De Rosa 6 , Ettore Del Monte 6 , Niccolò
    Di Lalla 40 , Alessandro Di Marco 6 , Immacolata Donnarumma 37 , Victor Doroshenko 42 , Michal Dovčiak 43 ,
    Teruaki Enoto 44 , Yuri Evangelista 6 , Sergio Fabiani 6 , Riccardo Ferrazzoli 6 , Javier A. Garcia 45 ,
    Shuichi Gunji 46 , Kiyoshi Hayashida 47 , Jeremy Heyl 48 , Wataru Iwakiri 49 , Philip Kaaret 4 , Vladimir Karas 43 ,
    Fabian Kislat 51 , Takao Kitaguchi 44 , Jeffery J. Kolodziejczak 4 , Henric Krawczynski 52 , Fabio La Monaca 6,8,7 ,
    Luca Latronico 32 , Simone Maldera 32 , Alberto Manfreda 53 , Frédéric Marin 54 , Andrea Marinucci 37 ,
    Francesco Massaro 32,33 , Giorgio Matt 31 , Ikuyuki Mitsuishi 55 , Fabio Muleri 6 , Michela Negro 56 ,
    Chi-Yung Ng 57 , Stephen L. O’Dell 4 , Nicola Omodei 40 , Chiara Oppedisano 32 , Alessandro Papitto 10 ,
    George G. Pavlov 58 , Abel Lawrence Peirson 40 , Matteo Perri 9,10 , Melissa Pesce-Rollins 29 ,
    Pierre-Olivier Petrucci 59 , Maura Pilia 11 , Andrea Possenti 11 , Juri Poutanen 1 , Simonetta Puccetti 9 ,
    Brian D. Ramsey 4 , John Rankin 6 , Ajay Ratheesh 6 , Oliver J. Roberts 4 , Carmelo Sgrò 29 , Patrick Slane 24 ,
    Paolo Soffitta 6 , Gloria Spandre 29 , Douglas A. Swartz 4 , Toru Tamagawa 44 , Roberto Taverna 60 ,
    Yuzuru Tawara 55 , Allyn F. Tennant 4 , Nicholas E. Thomas 4 , Francesco Tombesi 8,39,61 , Alessio Trois 11 ,
    Sergey S. Tsygankov 1 , Roberto Turolla 60,62 , Jacco Vink 63 , Martin C. Weisskopf 4 , Kinwah Wu 62 ,
    Fei Xie 6,64 , and Silvia Zane 62
    Affiliation:
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
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    18
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    23
    24
    25
    26
    27
    28
    29
    30
    31
    Department of Physics and Astronomy, University of Turku, FI-
    20014 Turku, Finland
    Finnish Centre for Astronomy with ESO (FINCA), Quantum,
    Vesilinnantie 5, FI-20014 University of Turku, Turku, Finland
    Aalto University Metsähovi Radio Observatory, Metsähovintie 114,
    FI-02540 Kylmälä, Finland
    NASA Marshall Space Flight Center, Huntsville, AL 35812, USA
    Institute of Astrophysics, Foundation for Research and Technology-
    Hellas, GR-70013 Heraklion, Greece
    INAF Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso
    del Cavaliere 100, 00133 Roma, Italy
    Dipartimento di Fisica, Università degli Studi di Roma “La
    Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
    Dipartimento di Fisica, Università degli Studi di Roma “Tor Ver-
    gata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    Space Science Data Center, Agenzia Spaziale Italiana, Via del
    Politecnico snc, 00133 Roma, Italy
    INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078
    Monte Porzio Catone (RM), Italy
    INAF Osservatorio Astronomico di Cagliari, Via della Scienza 5,
    09047 Selargius (CA), Italy
    INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807
    Merate (LC), Italy
    Institute for Astrophysical Research, Boston University, 725 Com-
    monwealth Avenue, Boston, MA 02215, USA
    MIT Kavli Institute for Astrophysics and Space Research, Mas-
    sachusetts Institute of Technology, 77 Massachusetts Avenue, Cam-
    bridge, MA 02139, USA
    South African Astronomical Observatory, PO Box 9, Observatory,
    7935 Cape Town, South Africa
    Department of Physics, University of Johannesburg, PO Box 524,
    Auckland Park, 2006 Johannesburg, South Africa
    Department of Physics, Graduate School of Advanced Science and
    Engineering, Hiroshima University Kagamiyama, 1-3-1, Higashi-
    Hiroshima, Hiroshima 739-8526, Japan
    Hiroshima Astrophysical Science Center, Hiroshima University, 1-
    3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
    Department of Physics, Tokyo Institute of Technology, 2-12-1
    Ookayama, Meguro-ku, Tokyo 152-8551, Japan
    Core Research for Energetic Universe (Core-U), Hiroshima Univer-
    sity, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526,
    Japan
    Planetary Exploration Research Center, Chiba Institute of Technol-
    ogy, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
    Institut de Radioastronomie Millimétrique, Avenida Divina Pastora,
    7, Local 20, E-18012 Granada, Spain
    Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-
    53121 Bonn, Germany
    Center for Astrophysics, Harvard & Smithsonian, 60 Garden Street,
    Cambridge, MA 02138, USA
    Korea Astronomy and Space Science Institute, 776 Daedeok-daero,
    Yuseong-gu, Daejeon 34055, Korea
    University of Science and Technology, Korea, 217 Gajeong-ro,
    Yuseong-gu, Daejeon 34113, Korea
    Section of Astrophysics, Astronomy & Mechanics, Department of
    Physics, National and Kapodistrian University of Athens, Panepis-
    timiopolis, Zografos 15784, Greece
    Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la
    Astronomía s/n, 18008 Granada, Spain
    Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pon-
    tecorvo 3, 56127 Pisa, Italy
    Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3,
    56127 Pisa, Italy
    Dipartimento di Matematica e Fisica, Università degli Studi Roma
    Tre, Via della Vasca Navale 84, 00146 Roma, Italy
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
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    43
    44
    45
    46
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    50
    Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via Pietro
    Giuria 1, 10125 Torino, Italy
    Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro
    Giuria 1, 10125 Torino, Italy
    INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5,
    50125 Firenze, Italy
    Dipartimento di Fisica e Astronomia, Università degli Studi di
    Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
    Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Via San-
    sone 1, 50019 Sesto Fiorentino (FI), Italy
    ASI - Agenzia Spaziale Italiana, Via del Politecnico snc, 00133
    Roma, Italy
    Science and Technology Institute, Universities Space Research
    Association, Huntsville, AL 35805, USA
    Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Ver-
    gata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
    Department of Physics and Kavli Institute for Particle Astrophysics
    and Cosmology, Stanford University, Stanford, CA 94305, USA
    Kavli Institute for Particle Astrophysics and Cosmology, Stanford
    University, and SLAC 2575 Sand Hill Road, Menlo Park, CA 94025,
    USA
    Institut für Astronomie und Astrophysik, Universität Tübingen,
    Sand 1, 72076 Tübingen, Germany
    Astronomical Institute of the Czech Academy of Sciences, Boční II
    1401/1, 14100 Praha 4, Czech Republic
    RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako,
    Saitama 351-0198, Japan
    NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
    Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata-shi 990-
    8560, Japan
    Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
    University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    International Center for Hadron Astrophysics, Chiba University,
    Chiba 263-8522, Japan
    St. Petersburg State University, 7/9, Universitetskaya nab., 199034
    St. Petersburg, Russia
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
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    Department of Physics and Astronomy and Space Science Center,
    University of New Hampshire, Durham, NH 03824, USA
    Physics Department and McDonnell Center for the Space Sciences,
    Washington University in St. Louis, St. Louis, MO 63130, USA
    Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Strada
    Comunale Cinthia, 80126 Napoli, Italy
    Université de Strasbourg, CNRS, Observatoire Astronomique de
    Strasbourg, UMR 7550, 67000 Strasbourg, France
    Graduate School of Science, Division of Particle and Astrophysical
    Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi
    464-8602, Japan
    Department of Physics and Astronomy, Louisiana State University,
    Baton Rouge, LA 70803, USA
    Department of Physics, The University of Hong Kong, Pokfulam,
    Hong Kong
    Department of Astronomy and Astrophysics, Pennsylvania State
    University, University Park, PA 16802, USA
    Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
    Dipartimento di Fisica e Astronomia, Università degli Studi di
    Padova, Via Marzolo 8, 35131 Padova, Italy
    Department of Astronomy, University of Maryland, College Park,
    MD 20742, USA
    Mullard Space Science Laboratory, University College London,
    Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
    Anton Pannekoek Institute for Astronomy & GRAPPA, Univer-
    sity of Amsterdam, Science Park 904, 1098 XH Amsterdam, The
    Netherlands
    Guangxi Key Laboratory for Relativistic Astrophysics, School of
    Physical Science and Technology, Guangxi University, Nanning
    530004, China
    Institute of Astronomy and NAO, Bulgarian Academy of Sciences,
    1784 Sofia, Bulgaria
    Astrophysics Research Institute, Liverpool John Moores University,
    Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool, UK
    Geological and Mining Institute of Spain (IGME-CSIC), Calle Ríos
    Rosas 23, E-28003 Madrid, Spain
    Abstract:
    We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155?304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half (T1) of the IXPE pointing, the source exhibited the highest X-ray polarization degree detected for an HSP blazar thus far, (30.7 ± 2.0)%; this dropped to (15.3 ± 2.1)% during the second half (T2). The X-ray polarization angle remained stable during the IXPE pointing at 129.4°?±1.8° and 125.4°?±3.9° during T1 and T2, respectively. Meanwhile, the optical polarization degree remained stable during the IXPE pointing, with average host-galaxy-corrected values of (4.3 ± 0.7)% and (3.8 ± 0.9)% during the T1 and T2, respectively. During the IXPE pointing, the optical polarization angle changed achromatically from ∼140° to ∼90° and back to ∼130°. Despite several attempts, we only detected (99.7% conf.) the radio polarization once (during T2, at 225.5 GHz): with degree (1.7 ± 0.4)% and angle 112.5°?±5.5°. The direction of the broad pc-scale jet is rather ambiguous and has been found to point to the east and south at different epochs; however, on larger scales (> 1.5 pc) the jet points toward the southeast (∼135°), similarly to all of the MW polarization angles. Moreover, the X-ray-to-optical polarization degree ratios of ∼7 and ∼4 during T1 and T2, respectively, are similar to previous IXPE results for several HSP blazars. These findings, combined with the lack of correlation of temporal variability between the MW polarization properties, agree with an energy-stratified shock-acceleration scenario in HSP blazars.
    Link:
    10.3847/1538-4357/ad5671
    Attache file:

  • Hyperfine structure of the methanol molecule as traced by Class I methanol masers    2024-09

    Publication:
    Monthly Notoces of trhe Royal Astronomical Society, 533, 1714
    Authors:
    I. I. Agafonova, 1 O. S. Bayandina , 2 Y. Gong, 3 , 4 C. Henkel, 3 , 5 ‹ Kee-Tae Kim, 6 , 7 M. G. Kozlov, 8 , 9
    B. Lankhaar, 10 S. A. Levshakov, 1 ‹ K. M. Menten, 3 W. Ubachs, 11 I. E. Val’tts 12 and W. Yang 3 , 13
    Affiliation:
    1 Ioffe
    Institute, 194021 St. Peter sburg , 26 Polytekhnicheskaya str, Russia
    Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy
    3 Max-Planck-Institut f ür Radioastronomie (MPIfR), Auf dem H ügel 69, D-53121 Bonn, Germany
    4 Purple Mountain Observatory, and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, People’s Republic
    of China
    5 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 830011 Urumqi, People’s Republic of China
    6 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea
    7 University of Science and Technology, Korea (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
    8 Department of Physics, Electrotechnical University ‘LETI’, 197376 St. Petersburg, Russia
    9 Petersburg Nuclear Physics Institute of NRC ‘Kurchatov Institute’, Gatchina, Leningrad District 188300, Russia
    10 Department of Space, Earth and Environment, Onsala Space Observatory, Chalmers University of Technology, Onsala 43992, Sweden
    11 Department of Physics and Astronomy, LaserLaB, Vrije Universiteit De Boelelaan 1081, NL-1081 HV Amsterdam, The Netherlands
    12 Astro Space Center, P.N. Lebedev Physical Institute of RAS, 84/32 Profsoyuznaya str, Moscow 117997, Russia
    13 School of Astronomy & Space Science, Nanjing University, 163 Xianlin avenue, Nanjing 210023, People’s Republic of China
    Abstract:
    We present results on simultaneous observations of Class I methanol masers at 25, 36, and 44 GHz towards 22 Galactic targets
    carried out with the Effelsberg 100-m telescope. The study investigates relations between the hyperfine (HF) structure of
    the torsion–rotation transitions in CH 3 OH and maser activity. By analysing the radial velocity shifts between different maser
    lines together with the patterns of the HF structure based on laboratory measurements and quantum-chemical calculations,
    we find that in any source only one specific HF transition forms the maser emission and that this transition changes from
    source to source. The physical conditions leading to this selective behaviour are still unclear. Using accurate laboratory rest
    frequencies for the 25 GHz transitions, we have refined the centre frequencies for the HF multiplets at 36, 44, and 95 GHz:
    f 36 = (36169 . 2488 ± 0 . 0002 stat ± 0 . 0004 sys ) MHz. f 44 = (44069 . 4176 ± 0 . 0002 stat ± 0 . 0004 sys ) MHz, and f 95 = (95169 . 4414 ±
    0 . 0003 stat ± 0 . 0004 sys ) MHz. Comparison with previous observations of 44 GHz masers performed 6–10 yr ago with a Korean
    21-m Korean Very Long Baseline Interferometry Network telescope towards the same targets confirms the kinematic stability
    of Class I maser line profiles during this time interval and reveals a systematic radial velocity shift of 0 . 013 ± 0 . 005 km s −1
    between the two telescopes.
    Link:
    10.1093/mnras/stae1815
    Attache file:

  • Investigating Asymmetry Development from SiO to H2O Maser Regions in VX Sagittarii    2024-09

    Publication:
    The Astronomical Journal, 168, 53
    Authors:
    Dong-Hwan Yoon 1
    1
    , Se-Hyung Cho 1,2
    , Youngjoo Yun 1
    , Haneul Yang 1
    , and Jaeheon Kim 1
    Affiliation:
    1 Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon, Republic of Korea
    2
    Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
    Abstract:
    Simultaneous very-long-baseline interferometry monitoring observations of H 2 O and SiO masers toward VX
    Sagittarii were conducted from 2014 February to 2019 January. Thirty epochs of observations revealed that the
    H 2 O and SiO masers had asymmetric and ring-like structures, respectively. However, from 2017 September to
    2018 March, the SiO maser transformed from a ring-like structure to a northeast–southwest (NE–SW) extension,
    and the 43.1 and 86.2 GHz SiO maser components had velocities of 39.48 and 10.65 km s −1 in the NE–SW
    direction, suggesting a possible localized strong shock wave. The H 2 O maser had a double-sided structure oriented
    in the NE–SW direction with near-stellar velocity components, which aligned with the extended direction of the
    SiO maser. The nonregular optical brightness and maser intensity variations were speculated to be related to the
    morphological evolution of the SiO maser. During the stable states attained by regular pulsations, the SiO maser
    region was presumed to experience radial acceleration, which reverted the SiO maser to a ring-like structure.
    However, the H 2 O maser region, where the acceleration almost terminates, retained its asymmetric morphology
    due to the prior influence of external forces. The results suggest that substantial energy transfer can alter the
    dynamics of the SiO maser and surrounding atmosphere, leading to an asymmetric distribution in the H 2 O maser
    region.
    Link:
    https://doi.org/10.3847/1538-3881/ad5005
    Attache file:

  • Limits of water maser kinematics: insights from the high-mass protostar AFGL 5142-MM1    2024-09

    Publication:
    Monthly Notoces of trhe Royal Astronomical Society, 527, 10031
    Authors:
    Zulfazli Rosli , 1 , 2 ‹ Ross A. Burns , 3 ‹ Affan Adly Nazri, 1 Koichiro Sugiyama, 4 Tomoya Hirota, 5 , 6
    Kee-Tae Kim, 7 , 8 Yoshinori Yonekura , 9 Liu Tie, 10 Gabor Orosz , 11 James Okwe Chibueze , 12 , 13 , 14
    Andrey M. Sobolev , 15 Ji Hyun Kang, 7 Chang Won Lee, 7 , 8 Jihye Hwang , 7 Hafieduddin Mohammad, 16
    Norsiah Hashim 17 and Zamri Zainal Abidin 1 ‹
    Affiliation:
    1 Department of Physics, Faculty of Science , Univer siti Malaya, 50603, Kuala Lumpur, Malaysia
    2 CFLMS, International University of Malaya Wales, Kuala Lumpur, Malaysia
    3 RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako-shi, Saitama,
    351-0198, Japan
    4 National Astronomical Research Institute of Thailand (Public Organization),
    260 Moo 4, T. Donkaew, A. Maerim, Chiangmai, 50180 Thailand
    5 Mizusawa VLBI Observatory, National Astronomical Observatory of Japan,
    Hoshigaoka 2-12, Mizusawa, Oshu, Iwate 023-0861, Japan
    6 The Graduate University for Advanced Studies, SOKENDAI, 2-21-1 Osawa,
    Mitaka, Tokyo 181-8588, Japan
    7 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-
    gu, Daejeon 34055, Republic of Korea
    8 University of Science and Technology, Korea (UST), 217 Gajeong-ro,
    Yuseong-gu, Daejeon 34113, Republic of Korea
    9 Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-
    8512, Japan
    10 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80
    Nandan Road, Shanghai 200030, People’s Republic of China
    11 Joint Institute for VLBI ERIC, Oude Hoo g eveensedijk 4, 7991 PD
    Dwingeloo, The Netherlands
    12 Department of Mathematical Sciences, University of South Africa, Cnr
    Christian de Wet Rd and Pioneer Avenue, Florida Park, 1709, Roodepoort,
    South Africa
    13 Centre for Space Research, Physics Department, North-West University,
    Potchefstroom 2520, South Africa
    Abstract:
    Multi-epoch very long baseline interferometry (VLBI) observations measure three-dimensional water maser motions in
    protostellar outflows, enabling analysis of inclination and v elocity. Howev er, these analyses assume that water masers and
    shock surfaces within outflows are co-propagating. We compare VLBI data on maser-traced bow shocks in the high-mass
    protostar AFGL 5142-MM1, from seven epochs of archival data from the VLBI Exploration of Radio Astrometry (VERA),
    obtained from 2014 April to 2015 May, and our newly conducted data from the KVN and VERA Array (KaVA), obtained in 2016
    March. We find an inconsistency between the expected displacement of the bow shocks and the motions of individual masers.
    The separation between two opposing bow shocks in AFGL 5142-MM1 was determined to be 337.17 ± 0.07 mas in the KaVA
    data, which is less than an expected value of 342.1 ± 0.7 mas based on extrapolation of the proper motions of individual maser
    features measured by VERA. Our measurements imply that the bow shock propagates at a velocity of 24 ± 3 km s ?1 , while the
    individual masing gas clumps mo v e at an average velocity of 55 ± 5 km s ?1 ; that is ,the water masers are moving in the outflow
    direction at double the speed at which the bow shocks are propagating. Our results emphasize that investigations of individual
    maser features are best approached using short-term high-cadence VLBI monitoring, while long-term monitoring on timescales
    comparable to the lifetimes of maser features is better suited to tracing the o v erall evolution of shock surfaces. Observers should
    be aware that masers and shock surfaces can mo v e relativ e to each other, and that this can affect the interpretation of protostellar
    outflows.
    Link:
    DOI 10.1093/mnras/stad3767
    Attache file:

  • A Multi-Wavelength Study on a Gamma-Ray Bright AGN 1308+326 Using KVN at 22 and 43 GHz    2024-09

    Publication:
    Journal Of The Korean Astronomical Society (한국천문학회지), 57, 1, 67
    Authors:
    Shan Li 1,2 , Sang-Sung Lee
    1,2,⋆
    , and Whee Yeon Cheong
    1,2
    Affiliation:
    1 Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
    2 University of Science and Technology, Daejeon 34113, Republic of Korea
    Abstract:
    In this study, we conduct a multi-frequency analysis of the gamma-ray bright blazar 1308+326 from February 2013 to March 2020, using the Korean VLBI Network at 22 and 43 GHz and gamma-ray data from the Fermi Large Area Telescope (LAT). Our findings reveal spectral variations around the 2014 gamma-ray flare, aligning with the shock-in-jet model. A strong correlation is observed between gamma-ray and 43 GHz emissions, with a 27-day lag in the VLBI core light curve, indicating a 50-day delay from the beginning of a specific radio flare to the gamma-ray peak. This radio flare correlates with a new jet component, suggesting the 2014 gamma-ray flare resulted from its interaction with a stationary component. Our analysis indicates the 2014 gamma-ray flare originated 40--63 parsecs from the central engine, with seed photons for the gamma-ray emission unlikely from the broad-line region.
    Link:
    DOI 10.5303/JKAS.2024.57.1.67
    Attache file:

  • A Study of the Radio Spectrum of Mrk 421    2024-04

    Publication:
    Astrophysical Journal, 964, 176
    Authors:
    Jee Won Lee 1
    1
    , Sang-Sung Lee 1,2
    , Jeffrey Hodgson 3 , Juan-Carlos Algaba 4 , Sanghyun Kim 1,2
    Hyeon-Woo Jeong 1,2 , and Sincheol Kang 1
    Affiliation:
    1 Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea; sslee@kasi.re.kr
    2
    University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
    3
    Department of Physics and Astronomy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul, Republic of Korea
    4
    Department of Physics, Faculty of Science, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
    Abstract:
    We present the results of a spectral analysis using simultaneous multifrequency (22, 43, 86, and 129 GHz) very long baseline interferometry (VLBI) observations of the Korean VLBI Network on BL Lac object, Markarian 421.
    The data we used were obtained from 2013 January to 2018 June. The light curves showed several flux enhancements with global decreases.
    To separate the variable and quiescent components in the multifrequency light curves for milliarcsecond-scale emission regions, we assumed that the quiescent radiation comes from the emission regions radiating constant optically thin synchrotron emissions (i.e., a minimum flux density with an optically thin spectral index). The quiescent spectrum determined from the multifrequency light curves was subtracted from the total CLEAN flux density, yielding a variable component in the flux that produces the timedependent spectrum. We found that the observed spectra were flat at 22?43 GHz, and relatively steep at 43?86 GHz, whereas the quiescent-corrected spectra are sometimes quite different from the observed spectra (e.g., sometimes inverted at 22?43 GHz). The quiescent-corrected spectral indices were much more variable than the observed spectral indices. This spectral investigation implies that the quiescent-spectrum correction can significantly affect the multifrequency spectral index of variable compact radio sources such as blazars. Therefore, the synchrotron self-absorption B-field strength (BSSA) can be significantly affected because BSSA is proportional to the fifth power of turnover frequency.
    Link:
    DOI 10.3847/1538-4357/ad2c91
    Attache file:

  • Detection of Extragalactic Anomalous Microwave Emission in NGC 2903 Using KVN Single-dish Observations    2024-03

    Publication:
    Astrophysical Journal, 963, 88
    Authors:
    Panomporn Poojon 1 , Aeree Chung 1
    1
    , Thiem Hoang 2,3 , Junhyun Baek 1,2
    Chao-Wei Tsai 7,8,9
    Affiliation:
    1 Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea; poojon.p@gmail.com, achung@yonsei.ac.kr
    2
    Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea; thiemhoang@kasi.re.kr
    3
    Department of Astronomy and Space Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
    4
    Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
    5
    Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshiga-oka, Mizusawa, Oshu-shi, Iwate 023-0861, Japan
    6
    The Graduate University for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
    7
    National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100101, Peopleʼs Republic of China
    8
    Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, Peopleʼs Republic of China
    9
    School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, Peopleʼs Republic of China
    Abstract:
    We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous
    microwave emission (AME) in nearby galaxies. The targets were selected from ‘Mapping the dense molecular gas
    in the strongest star-forming galaxies' (MALATANG), a legacy survey project of the James Clerk Maxwell
    Telescope. The MALATANG galaxies are good representatives of local galaxies with enhanced nuclear activity
    associated with star formation and/or active galactic nuclei (AGNs), providing IR-bright galaxy samples; thus,
    they are good candidates for AME hosts. Combining with ancillary data, we investigated the radio–IR spectral
    energy distribution (SED), while searching for AME signals in five galaxies. The AME in NGC 2903 was well
    detected at a significant confidence level, whereas that in NGC 2146 and M82 was marginal. NGC 1068 and Arp
    299 indicated no significant hints, and we provide upper limits for the AME. The best-fit SED exhibited local peaks
    of the AME components at higher frequencies and with stronger peak fluxes than those in previous studies. This
    suggested that AME originates from denser environments such as molecular clouds or photodissociation regions
    rather than warm neutral/ionized medium as commonly suggested by previous studies. Further, our AME-detected
    targets were observed to exhibit higher specific star formation rates than the other extragalactic AME hosts.
    Furthermore, AME favored starburst galaxies among our sample rather than AGN hosts. Consequently, this might
    imply that AGNs are excessively harsh environments for tiny dust to survive.
    Link:
    DOI 10.3847/1538-4357/ad1bc8
    Attache file: