Seong-Min Son 1,2 aa, Se-Hyung Cho 2,3 aa, Jaeheon Kim 3 aa, Hyeon Baek 1,3 aa, Dong-Hwan Yoon 3 aa, and Kyung-Won Suh 1
Affiliation:
1
Department of Astronomy and Space Science, Chungbuk National University, Cheongju-City, 28644, Republic of Korea
2
Department of Physics and Astronomy, Seoul National University, Gwanakgu, Seoul 08826, Republic of Korea; cho@kasi.re.kr
3
Korea Astronomy and Space Science Institute, 776 Daedeok–daero, Yuseong–gu, Daejeon 34055, Republic of Korea
Abstract:
We present the observational results of Simultaneous Multi-mAser Survey Toward Evolved Stars (SMASTES) II
for 150 S-type asymptotic giant branch stars. Observations have been performed from 2023 September to 2024
March using the upgraded wide four-band (22/43/86/129 GHz) receiving system of the Korean VLBI Network.
For simultaneous observations, 19 molecular lines of H 2 O and multitransitions of SiO masers including several
thermal lines were set up together. H 2 O maser was not detected from any stars among 150 S-type stars. For SiO
v = 1: J = 1–0, J = 2–1, and J = 3–2 masers were detected from nine, thirteen, and six stars, respectively. For SiO
v = 2: J = 1–0, J = 2–1, and J = 3–2 masers were detected from five, two, and two stars, respectively. In particular,
for v = 1: J = 1–0, J = 2–1, and J = 3–2 masers were all detected from five stars. For SiO v = 0: J = 1–0, J = 2–1,
and J = 3–2 lines in ground vibrational state were detected from five, six, and seven stars, respectively, including the
29
SiO v = 0: J = 1–0 and J = 2–1 lines. For SiO v = 0: J = 1–0, J = 2–1, and J = 3–2 lines were detected in more
stars at higher rotational transition lines. The carbon-bearing molecule HCN was detected from four stars. Based on
these observational results, we perform statistical analyses on detection rates of maser and thermal lines, maser
properties, and kinematics comparing with the results of M-type stars (SMASTES I). The characteristics of maser
properties are investigated in the IRAS two-color diagram in relation to the evolutionary stage.
The Astrophysical Journal Supplement Series, Volume 280, 25 (2025)
Authors:
Tianwei Zhang (张天惟) 1 aa, Tie Liu 2 aa, Yuefang Wu 3 aa, Linjing Feng 4,5 aa, Sihan Jiao 4,6 aa, Derek Ward-Thompson 7 aa,
Alessio Traficante 8 aa, Helen J Fraser 9 aa, James Di Francesco 10,11 aa, Doug Johnstone 10,11 aa, Paul F. Goldsmith 12 aa,
Yasuo Doi 13 aa, Xunchuan Liu 2 aa, Chang Won Lee 14 aa, Fengwei Xu 3,15 aa, Ram K. Yadav 16 aa, Glenn J White 17,18 aa,
Leonardo Bronfman 19 aa, Yi-Jehng Kuan 20 aa, Kee-Tae Kim 14 aa, and Donghui Quan 1
Affiliation:
1 Research Center for Astronomical Computing, Zhejiang Laboratory, Hangzhou, People’s Republic of China
2 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China
3 Department of Astronomy, Peking University, 100871, Beijing, People’s Republic of China
4 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
5 University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
6 Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg, Germany
7 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
8 INAF—Istituto di Astrofisica e Planetologia Spaziali (IAPS), Via Fosso del Cavaliere 100, I-00133 Roma, Italy
9 School of Physical Sciences, Open University, Milton Keynes, MK7 6AA, UK
10 NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
11 Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 5C2, Canada
12 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
13 Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
14 Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348, Republic of Korea
15 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China
16 National Astronomical Research Institute of Thailand (NARIT), Sirindhorn AstroPark, 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai 50180, Thailand
17 Department of Physics & Astronomy, Open University, Milton Keynes MK7 6AA, UK
18 RAL Space, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 9DL, UK
19 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
20 Department of Earth Science, National Taiwan Normal University, Taipei, 11677, Taiwan, People’s Republic of China
Abstract:
We present compelling observational evidence supporting G178.28-00.61 as an early-stage candidate for cloud–
cloud collision (CCC), with indications of the formation of an S-shaped filament, evenly separated dense cores,
and young star clusters. The observations of CO molecular line emission demonstrate the existence of two
interacting molecular clouds with systemic velocities of 0.8 km s −1 and −1.2 km s −1 , respectively. The
convergence zone of these two clouds reveals an S-shaped filament in the James Clerk Maxwell Telescope
850 μm continuum image, suggesting cloud interaction. In line with expectations from CCC simulations, broad
bridging features are discernible in the position–velocity diagrams. An elevated concentration of identified Class I
and II young stellar objects along the filament at the intersection area further supports the hypothesis of a
collision-induced origin. This observation could be explained by a recent MHD model of CCC, which predicts a
similar morphology, scale, density, and unbound status, as well as the orientation of the polarization.
Hyeon Baek 1,2 aa, Se-Hyung Cho 1,3 aa, Jaeheon Kim 3 aa, Seung-Min Son 1,2 aa, Dong-Hwan Yoon 3 aa, and Kyung-Won Suh 2 aa
Affiliation:
1Department of Physics and Astronomy, Seoul National University, Gwanakgu, Seoul 08826, Republic of Korea; cho@kasi.re.kr
2Department of Astronomy and Space Science, Chungbuk National University, Cheongju-City, 28644, Republic of Korea
3Korea Astronomy and Space Science Institute, 776 Daedeok–daero, Yuseong–gu, Daejeon 34055, Republic of Korea
Abstract:
Simultaneous observations of 19 H2O and SiO maser and thermal lines were performed toward 155 M-type oxygen-rich (O-rich) AGB stars. We used the upgraded four-band (22/43/86/129 GHz) wide receiving system of the Korean VLBI Network (KVN). The 155 O-rich stars composed of 50 semiregulars (SRs), 55 Miras, and 50 OH/IR stars were selected based on previous KVN H2O/SiO detected sources. Both H2O and SiO masers were detected in 23 stars among 50 SRs, 50 stars among 55 Miras, and 24 stars among 50 OH/IRs, respectively. Out of 50 SRs, H2O-only masers, without corresponding SiO maser detection, were observed in four stars. In contrast, no H2O-only masers were detected in any of the 55 Mira or 50 OH/IR stars, which differs from the pattern seen with SiO-only masers. Interestingly, in the 50 SRs, the SiO v = 1, J = 2？1 maser was detected more than the SiO v = 1, J = 1？0 maser despite requiring a higher excitation energy. The 28SiO v = 0, J = 1？0, 2？1, 3？2 lines were detected more frequently at higher rotational transitions, especially in the SRs and Miras. The HCN and SiS were detected from 11 and 3 stars, respectively. For our observational results, we performed statistical analysis on the intensity ratio variations among H2O and various SiO masers, chemical environments, and wind kinematics. The characteristics of these property variations were investigated in the IRAS two-color diagram in relation to their evolutionary stages.
Publications of the Astronomical society of Japan, 2025, 77,678
Authors:
Jeong-Sook K IM , 1 , 2 , 3 , * Nobuyuki S AKAI , 4 , 5 Soon-Wook K IM , 3 , * Tomoaki O YAMA , 5
Kazuya H ACHISUKA , 5 and Kimitake H AYASAKI 2 , 6 , 7
Affiliation:
1
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
Department of Astronomy and Space Science, Chungbuk National University, Cheongju 361-763, Republic of Korea
3
Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea
4
National Astronomical Research Institute of Thailand ( Public Organization) , 260 Moo 4, T. Donkaew, A. Maerim, Chiang Mai 50180, Thailand
5
Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshiga-oka, Mizusawa, Oshu-shi, Iwate 023-0861, Japan
6
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
7
Department of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
Abstract:
We carry out astrometric Very Long Baseline Interferometry ( VLBI) observations for Cygnus X-3, a high-mass X-ray binary ( HMXB) , with the
Korean–Japanese joint VLBI array ( KaVA) from 2020 to 2021. The observations have been optimized for the subdued phase when Cygnus X-
3 is relatively faint, sidestepping a giant flare between 2020 and 2021. The position of the core in Cygnus X-3 was measured through the
observations. Based on accumulating core positions from the available archival dat a, obt ained over ∼38 yr with the Very Large Array ( VLA) ,
the Very Long Baseline Array ( VLBA) , and the European VLBI Network ( EVN) , in addition to our KaVA observations, we estimated the proper
motion components to be μ α cos δ = −2 . 720 ± 0 . 019 mas yr −1 and μ δ = −3 . 693 ± 0 . 019 mas yr −1 in RA and Dec, and μ l cos b = −4 . 587 ± 0 . 027
mas yr −1 and μ b = −0 . 001 ± 0 . 004 mas yr −1 in galactic longitude and galactic latitude, respectively. The proper motion results are in good
agreement with previous results. Furthermore, the uncertainties we obtained are reduced by a factor of 3. The proper motion measurement
allows us to constrain the peculiar velocity of the system in three-dimensional space to be 292 ± 127 km s −1 with 1 σ error. Based on the
correlation between the orbital period and the peculiar velocity in HMXBs, a peculiar velocity with an orbital period of 0.2 d, like that of Cygnus
X-3, is expected to be higher than 100 km s −1 within 1 σ error. This suggests the possibility that the compact star probably received a substantial
kick during its birth, most likely caused by a supernova explosion rather than a direct collapse.
Haitian Shang 1,2,3 aa, Wei Zhao 1 aa, Xiaoyu Hong 1,2,3,4 aa, Leonid I. Gurvits 1,5,6 aa, Ailing Zeng 1,2 aa, Tao An 1 aa, and
Xiaopeng Cheng 7
Affiliation:
1
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China; htshang@shao.ac.cn, xhong@shao.ac.cn
2
School of Physical Science and Technology, Shanghai Tech University, 100 Haike Road, Pudong, Shanghai 201210, People’s Republic of China
3
School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
4
College of Physical Science and Technology, Xiamen University, Xiamen 361005, People’s Republic of China
5
Joint Institute for VLBI ERIC, Oude Hoogeveensedijk 4, Dwingeloo, 7991 PD, The Netherlands
6
Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, Delft, 2629 HS, The Netherlands
7
Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
Abstract:
We present an investigation of the compact structure of the active galactic nucleus 2021+317 based on
multiepoch very long baseline interferometry (VLBI) observations at 15, 22, and 43 GHz in the period from 2013
through 2024. The VLBI images show a core–jet structure extended to the south, with two stationary components
in the northern region, one of which is likely to be the core of the source. We also detected two new moving jet
components (S4 and S5) in the observations of 2021. Based on these observational findings, we analyzed two
distinctive jet models involving one or another stationary component mentioned above as the jet core. One model
assumes a moderate bulk motion velocity, a wider viewing angle, and a lower Doppler factor, with the magnetic
field energy density significantly dominating over the nonthermal particle energy density. The other model
involves a higher bulk motion velocity, a narrower viewing angle, and a higher Doppler factor, with an even
greater dominance of magnetic field energy in the core. The position angle of the jet ridgeline rotates
counterclockwise over the observed period. The apparent kinematics of the jet components is more consistent
with a model of the precessing jet, which has recently completed the first half of the precession cycle. Our results
provide constraints on the dynamic evolution of the jet and its interaction with the surrounding medium.
Ioannis Liodakis 1,2,3,? , Haocheng Zhang 4,5 , Stella Boula 6 , Riccardo Middei 7,8 , Jorge Otero-Santos 9,10 ,
Dmitry Blinov 1,11 , Iván Agudo 9 ,, Markus Böttcher 12 , Chien-Ting Chen 13 , Steven R. Ehlert 3 ,
Svetlana G. Jorstad 14,15 , Philip Kaaret 3 , Henric Krawczynski 16 , Abel L. Peirson 17 , Roger W. Romani 17 ,
Fabrizio Tavecchio 6 , Martin C. Weisskopf 3 , Pouya M. Kouch 18,19,20 , Elina Lindfors 18,19 , Kari Nilsson 19 ,
Callum McCall 21 , Helen E. Jermak 21 , Iain A. Steele 21 , Ioannis Myserlis 22,2 , Mark Gurwell 23 ,
Garrett K. Keating 23 , Ramprasad Rao 23 , Sincheol Kang 24 , Sang-Sung Lee 24,25 , Sanghyun Kim 24,25 ,
Whee Yeon Cheong 24,25 , Hyeon-Woo Jeong 24,25 , Emmanouil Angelakis 26 , Alexander Kraus 2 ,
Francisco José Aceituno 9 , Giacomo Bonnoli 6,9 , Víctor Casanova 9 , Juan Escudero 9 , Beatriz Agís-González 1 ,
Daniel Morcuende 9 , Alfredo Sota 9 , Rumen Bachev 27 , Tatiana S. Grishina 15 , Evgenia N. Kopatskaya 15 ,
Elena G. Larionova 15 , Daria A. Morozova 15 , Sergey S. Savchenko 15,28 , Ekaterina V. Shishkina 15 ,
Ivan S. Troitskiy 15 , Yulia V. Troitskaya 15 , and Andrey A. Vasilyev 15
Affiliation:
1
2
3
4
5
6
7
8
9
10
11
12
13
Institute of Astrophysics, Foundation for Research and Technology-
Hellas, GR-70013 Heraklion, Greece
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-
53121 Bonn, Germany
NASA Marshall Space Flight Center, Huntsville, AL 35812, USA
University of Maryland Baltimore County Baltimore, Baltimore,
MD 21250, USA
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807
Merate, (LC), 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
Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la
Astronomía s/n, 18008 Granada, Spain
Istituto Nazionale di Fisica Nucleare, Sezione di Padova, 35131
Padova, Italy
Department of Physics, University of Crete, GR-70013 Heraklion,
Greece
Centre for Space Research North-West University Potchefstroom,
Potchefstroom 2531, South Africa
Science and Technology Institute, Universities Space Research
Association, Huntsville, AL 35805, USA
14
15
16
17
18
19
20
Institute for Astrophysical Research, Boston University, 725 Com-
monwealth Avenue, Boston, MA 02215, USA
St. Petersburg State University, 7/9, Universitetskaya nab., 199034
St. Petersburg, Russia
Physics Department and McDonnell Center for the Space Sci-
ences, Washington University in St. Louis, St. Louis, MO 63130,
USA
Department of Physics and Kavli Institute for Particle Astrophysics
and Cosmology, Stanford University, Stanford, California 94305,
USA
Department of Physics and Astronomy, University of Turku, Turku
FI-20014, Finland
Finnish Centre for Astronomy with ESO (FINCA), Quantum,
Vesilinnantie 5, FI-20014 University of Turku, Finland
Aalto University Metsähovi Radio Observatory, Metsähovintie 114,
FI-02540 Kylmälä, Finland
21
22
23
24
25
26
27
28
Astrophysics Research Institute, Liverpool John Moores University,
Liverpool Science Park IC2, Liverpool, 146 Brownlow Hill, UK
Institut de Radioastronomie Millimétrique, Avenida Divina Pastora,
7, Local 20, E-18012 Granada, Spain
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
Institute of Astronomy and NAO, Bulgarian Academy of Sciences,
1784 Sofia, Bulgaria
Pulkovo Observatory, St.Petersburg 196140, Russia
Abstract:
The origin of the high-energy emission in astrophysical jets from black holes is a highly debated issue. This is particularly true for jets from
supermassive black holes, which are among the most powerful particle accelerators in the Universe. So far, the addition of new observations and
new messengers have only managed to create more questions than answers. However, the newly available X-ray polarization observations promise
to finally distinguish between emission models. We use extensive multiwavelength and polarization campaigns as well as state-of-the-art polarized
spectral energy distribution models to attack this problem by focusing on two X-ray polarization observations of blazar BL Lacertae in flaring and
quiescent γ-ray states. We find that, regardless of the jet composition and underlying emission model, inverse-Compton scattering from relativistic
electrons dominates at X-ray energies.
Motoki Kino 1,2 aa, Masahiro Nagashima 3 aa, Hyunwook Ro 4 aa, Yuzhu Cui 5,6 aa, Kazuhiro Hada 7,8 aa, and Jongho Park 9,10
Affiliation:
1
Kogakuin University of Technology & Engineering, Academic Support Center, 2665-1 Nakano-machi, Hachioji, Tokyo 192-0015, Japan; motoki.kino@gmail.com
2
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
3
Faculty of Education, Bunkyo University, 3337, Minami-ogishima, Koshigaya, Saitama 343-8511, Japan
4
Korea Astronomy & Space Science Institute, Daedeokdae-ro 776, Yuseong-gu, Daejeon 34055, Republic of Korea
5
Institute of Astrophysics, Central China Normal University, Wuhan 430079, People’s Republic of China
6
Research Center for Astronomical Computing, Zhejiang Lab, Hangzhou 311100, People’s Republic of China
7
Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, 467-8501, Aichi, Japan
8
Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka-cho, Mizusawa, Oshu, 023-0861, Iwate, Japan
9
School of Space Research, Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea
10
Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan
Abstract:
Galaxy mergers, each hosting a supermassive black hole (SMBH), are thought to form SMBH binaries. Motivated
by recent observations from the East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) showing
periodic behavior in the M87 jet, a precession of about 11 yr and a transverse oscillation of about 0.9 yr, we
constrain the mass of a hypothetical secondary black hole orbiting the primary SMBH in M87. To constrain the
mass ratio between the primary SMBH (M 1 ) and the secondary black hole (M 2 ) defined as q ≡ M 2 /M 1 � 1, and the
length of the semimajor axis of the binary system (a), we impose the following three constraints: (i) the lower limit
of a, below which the SMBH binary is expected to merge; (ii) the strain amplitude of the gravitational-wave
background at nanohertz frequencies shown in the NANOGrav 15 yr data set; and (iii) a finite length of the
semimajor axis of M 1 , which can induce periodic behavior in the jet. By combining these constraints, we obtain the
allowed parameter space for q and a. If either of the EAVN-detected periods (T) corresponds to the binary’s orbital
period, the allowed range of q is 6.9 × 10 −3 � q � 4.2 × 10 −2 for T ≈ 11 yr, and 3.7 × 10 −2 � q � 1 for T ≈ 0.9 yr.
VLBI astrometric monitoring of the jet base of M87 is essential to explore the allowed parameter space for q and a.
Hyunjin Shim 1 , Junhyun Baek 2 , Dohyeong Kim 3 , Minjin Kim 4 , Hyunmi Song 5 , Gu Lim 3,6 , Jaejun Cho 4 ,
3, Hayeong Jeong, Yejin Jeong 1 , Ye-eun Kang 4 , Dongseob Lee 1 , Junyeong Park 3 , Eunsuk Seo 5 , Junho Song 5 , and Been Yeo 2,7
Affiliation:
1Department of Earth Science Education, Kyungpook National University, Daegu 41566, Republic of Korea; hjshim@knu.ac.kr
2Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
3Department of Earth Sciences, Pusan National University, Busan 46241, Republic of Korea
4Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
5Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134, Republic of Korea
6Institute for Future Earth (IFE), Pusan National University, Busan 46241, Republic o
Abstract:
We present CO(1？0) observations of 50 star-forming galaxies at 0.01 < z < 0.35, for which 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission flux or its upper limit is available. A scaling relation between 3.3 μm PAH luminosity and CO(1？0) luminosity is established covering ∼2 orders of magnitude in total IR luminosity and CO luminosity, with a scatter of ∼0.23 dex: = +(？1.10 ± 0.70). The slope is near unity, allowing the use of a single value of =？1.09 ± 0.36 [L⊙/(K km s？1 pc2)] in the conversion between 3.3 μm PAH and CO luminosities. The variation in the ratio is not dependent on the galaxy properties, including total IR luminosity, stellar mass, and star formation rate excess. The total gas mass, estimated using the dust-to-gas ratio and dust mass, is correlated with 3.3 μm PAH luminosity, in line with the prescription using αCO = 0.8？4.5 covering both normal star-forming galaxies and starburst galaxies. Active galactic nucleus (AGN)-dominated galaxies tend to have a lower than non-AGN galaxies, which needs to be investigated further with an increased sample size. The established L3.3？ correlation is expected to be applicable to wide-field near-infrared spectrophotometric surveys that allow the detection of 3.3 μm emission from numerous low-redshift galaxies.
Iván Agudo 1 , Ioannis Liodakis 2,3 , Jorge Otero-Santos 1,4 , Riccardo Middei 5,6,7 , Alan Marscher 8 , Svetlana Jorstad 8,9 ,
Haocheng Zhang 10,11 , Hui Li 12 , Laura Di Gesu 13 , Roger W. Romani 14 , Dawoon E. Kim 15,16,17 , Francesco Fenu 13 ,
Herman L. Marshall 18 , Luigi Pacciani 15 , Juan Escudero Pedrosa 1,7 , Francisco José Aceituno 1 , Beatriz Agís-González 1,3 ,
Giacomo Bonnoli 1,19 , Víctor Casanova 1 , Daniel Morcuende 1 , Vilppu Piirola 20 , Alfredo Sota 1 , Pouya M. Kouch 20,21 ,
Elina Lindfors 20 , Callum McCall 22 , Helen E. Jermak 22 , Iain A. Steele 22 , George A. Borman 23 , Tatiana S. Grishina 9 ,
Vladimir A. Hagen-Thorn 9 , Evgenia N. Kopatskaya 9 , Elena G. Larionova 9 , Daria A. Morozova 9 ,
Sergey S. Savchenko 9,24 , Ekaterina V. Shishkina 9 , Ivan S. Troitskiy 9 , Yulia V. Troitskaya 9 , Andrey A. Vasilyev 9 ,
Alexey V. Zhovtan 23 , Ioannis Myserlis 25,26 , Mark Gurwell 7 , Garrett Keating 7 , Ramprasad Rao 7 , Sincheol Kang 27 ,
Sang-Sung Lee 27,28 , Sanghyun Kim 27,28 , Whee Yeon Cheong 27,28 , Hyeon-Woo Jeong 27,28 , Emmanouil Angelakis 29 ,
Alexander Kraus 26 , Dmitry Blinov 3,30 , Siddharth Maharana 31 , Rumen Bachev 32 , Jenni Jormanainen 20,21 ,
Kari Nilsson 21 , Vandad Fallah Ramazani 21,33 , Carolina Casadio 3,30 , Antonio Fuentes 1 , Efthalia Traianou 1 ,
Clemens Thum 25 , José L. Gómez 1 , Lucio Angelo Antonelli 6 , Matteo Bachetti 34 , Luca Baldini 35,36 ,
Wayne H. Baumgartner 2 , Ronaldo Bellazzini 35 , Stefano Bianchi 37 , Stephen D. Bongiorno 2 , Raffaella Bonino 38,39 ,
Alessandro Brez 35 , Niccolò Bucciantini 40,41,42 , Fiamma Capitanio 15 , Simone Castellano 35 , Elisabetta Cavazzuti 13 ,
Chien-Ting Chen 43 , Stefano Ciprini 5,44 , Enrico Costa 15 , Alessandra De Rosa 15 , Ettore Del Monte 15 ,
Niccolò Di Lalla 14 , Alessandro Di Marco 15 , Immacolata Donnarumma 13 , Victor Doroshenko 45 , Michal Dovčiak 46 ,
Steven R. Ehlert 2 , Teruaki Enoto 47 , Yuri Evangelista 15 , Sergio Fabiani 15 , Riccardo Ferrazzoli 15 , Javier A. García 11 ,
Shuichi Gunji 48 , Kiyoshi Hayashida 49 , Jeremy Heyl 50 , Wataru Iwakiri 51 , Philip Kaaret 2 , Vladimir Karas 46 ,
Fabian Kislat 52 , Takao Kitaguchi 47 , Jeffery J. Kolodziejczak 2 , Henric Krawczynski 53 , Fabio La Monaca 15,17 ,
Luca Latronico 38 , Simone Maldera 38 , Alberto Manfreda 54 , Frédéric Marin 55 , Andrea Marinucci 13 ,
Francesco Massaro 38,39 , Giorgio Matt 37 , Ikuyuki Mitsuishi 56 , Tsunefumi Mizuno 57 , Fabio Muleri 15 , Michela Negro 58 ,
Chi-Yung Ng 59 , Stephen L. O’Dell 2 , Nicola Omodei 14 , Chiara Oppedisano 38 , Alessandro Papitto 6 ,
George G. Pavlov 60 , Abel L. Peirson 14 , Matteo Perri 5,6 , Melissa Pesce-Rollins 35 , Pierre-Olivier Petrucci 61 ,
Maura Pilia 34 , Andrea Possenti 34 , Juri Poutanen 20 , Simonetta Puccetti 5 , Brian D. Ramsey 2 , John Rankin 15 ,
Ajay Ratheesh 15 , Oliver J. Roberts 43 , Carmelo Sgrò 35 , Patrick Slane 7 , Paolo Soffitta 15 , Gloria Spandre 35 ,
Douglas A. Swartz 43 , Toru Tamagawa 47 , Fabrizio Tavecchio 19 , Roberto Taverna 62 , Yuzuru Tawara 56 ,
Allyn F. Tennant 2 , Nicholas E. Thomas 2 , Francesco Tombesi 17,44 , Alessio Trois 34 , Sergey S. Tsygankov 20 ,
Roberto Turolla 62,63 , Jacco Vink 64 , Martin C. Weisskopf 2 , Kinwah Wu 63 , Fei Xie 15,65 , and Silvia Zane 63
Affiliation:
1 Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain; iagudo@iaa.es
2
NASA Marshall Space Flight Center, Huntsville, AL 35812, USA; yannis.liodakis@gmail.com
3
Institute of Astrophysics, Foundation for Research and Technology - Hellas, Voutes, 7110, Heraklion, Greece
4
Istituto Nazionale di Fisica Nucleare, Sezione di Padova, 35131 Padova, Italy; jorge.otero@pd.infn.it
5
Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico snc, I-00133 Roma, Italy; riccardo.middei@ssdc.asi.it
6
INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (RM), Italy
7
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
8
Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA; marscher@bu.edu
9
Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia
10
University of Maryland Baltimore County, Baltimore, MD 21250, USA
11
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
12
Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
13
ASI - Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
14
Department of Physics and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA
15
INAF, Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, 00133 Roma, Italy
16
Dipartimento di Fisica, Universitá degli Studi di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Roma, Italy
17
Dipartimento di Fisica, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
18
MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
19
INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
20
Department of Physics and Astronomy, Quantum, Vesilinnantie 5, FI-20014 University of Turku, Finland
21
Finnish Centre for Astronomy with ESO (FINCA), 20014, University of Turku, Finland
22
Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park IC 2, 146 Brownlow Hill, UK
23
Crimean Astrophysical Observatory RAS, P/O Nauchny, 298409, Crimea, Russia
24
Pulkovo Observatory, St. Petersburg, 196140, Russia
25
Institut de Radioastronomie Millimétrique, Avenida Divina Pastora, 7, Local 20, E-18012 Granada, Spain
26
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
27
Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea
28
University of Science and Technology, Korea, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
29
Orchideenweg 8, 53123 Bonn, Germany
30
Department of Physics, University of Crete, 70013, Heraklion, Greece
31
South African Astronomical Observatory, PO Box 9, Observatory, 7935, Cape Town, South Africa
32
Institute of Astronomy and NAO, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
33
Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
Dipartimento di Fisica, Universitá di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
37
Dipartimento di Matematica e Fisica, Universitá degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
38
Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
39
Dipartimento di Fisica, Universitá degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
40
INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
41
Dipartimento di Fisica e Astronomia, Universitá degli Studi di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
42
Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
43
Science and Technology Institute, Universities Space Research Association, Huntsville, AL 35805, USA
44
Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
45
Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
46
Astronomical Institute of the Czech Academy of Sciences, Bočn( ́ı) II 1401/1, 14100 Praha 4, Czech Republic
47
RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
48
Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata-shi 990-8560, Japan
49
Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
50
University of British Columbia, Vancouver, BC V6T 1Z4, Canada
51
International Center for Hadron Astrophysics, Chiba University, Chiba 263-8522, Japan
52
Department of Physics and Astronomy and Space Science Center, University of New Hampshire, Durham, NH 03824, USA
53
Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA
54
Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Strada Comunale Cinthia, 80126 Napoli, Italy
55
Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
56
Graduate School of Science, Division of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
57
Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
58
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
59
Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China
60
Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA
61
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
62
Dipartimento di Fisica e Astronomia, Universitá degli Studi di Padova, Via Marzolo 8, 35131 Padova, Italy
63
Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
64
Anton Pannekoek Institute for Astronomy & GRAPPA, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
65
Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, People’s Republic of
China
Abstract:
Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most
powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray
multiwavelength campaign on the blazar BL Lacertae with unprecedented polarimetric coverage from radio to
X-ray wavelengths. The observations caught an extraordinary event on 2023 November 10？18, when the degree of
linear polarization of optical synchrotron radiation reached a record value of 47.5%. In stark contrast, the Imaging
X-ray Polarimetry Explorer found that the X-ray (Compton scattering or hadron-induced) emission was polarized
at less than 7.4% (3σ confidence level). We argue here that this observational result rules out a hadronic origin of
the high-energy emission and strongly favors a leptonic (Compton scattering) origin, thereby breaking the
degeneracy between hadronic and leptonic emission models for BL Lacertae and demonstrating the power of
multiwavelength polarimetry to address this question. Furthermore, the multiwavelength flux and polarization
variability, featuring an extremely prominent rise and decay of the optical polarization degree, is interpreted for the
first time by the relaxation of a magnetic “spring” embedded in the newly injected plasma. This suggests that the
plasma jet can maintain a predominant toroidal magnetic field component parsecs away from the central engine.
Hyeon-Woo Jeong 1,2 , Sang-Sung Lee 1,2? , Sincheol Kang 2 , Minchul Kam 3,4 , Sanghyun Kim 1,2 ,
Whee Yeon Cheong 1,2 , Do-Young Byun 1,2 , Chanwoo Song 1,2 , and Sascha Trippe 4,5
Affiliation:
1 Astronomy and Space Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113,
Republic of Korea
2 Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea
3 Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan
4 Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
5 SNU Astronomy Research Center, Seoul National University, Gwanak-gu, Seoul 08826, Korea
Abstract:
Context. The blazar 3C 454.3 (z = 0.859) has been extensively investigated using multiwavelength high-resolution polarization studies, showing polarization variations on milliarcsecond scales.
Aims. This study investigates the polarimetric characteristics of the blazar 3C 454.3 at 22？129 GHz using decadal (2011？2022) data sets. In addition, we also delve into the origin of the polarization flare observed in 2019.
Methods. The corresponding data sets were obtained from the single-dish mode observations of the Korean VLBI Network (KVN) and the 43 GHz Very Long Baseline Array (VLBA). Using those data, we compared the consistency of the measurements between milliarcsecond and arcsecond scales. The Faraday rotation measure (RM) values were obtained via two approaches: model fitting to a linear function in all frequency ranges and calculating from adjacent frequency pairs.
Results. We found that the preferred linear polarization angle is ∼100° when the source is highly polarized, for example during a flare. At 43 GHz we found that the polarized emission at of milliarcsecond and arcsecond scales is consistent when we compare its flux density and polarization angle. The ratio of quasi-simultaneously measured (within a week) polarized flux density is 1.02 ± 0.07 (i.e., ΔS_p/S_p ？ 2%) and the polarization angles display similar rotation, which suggest that the extended jet beyond the scale of VLBA 43 GHz has a negligible convolution effect on the polarization angle from the KVN. We found an interesting and notable flaring event in the KVN single-dish data from the polarized emission in 2019 in the frequency range of 22？129 GHz. During the flare, the observed polarization angles (χ_obs) rotate from ∼150° to ∼100° at all frequencies with a chromatic polarization degree (m_p).
Conclusions. Based on the observed m_p and χ_obs, and also on the Faraday rotation measure, we suggest that the polarization flare in 2019 is attributed to the shock？shock interaction in the stationary jet region. The change in the viewing angle of the jet alone is insufficient to describe the increase in brightness temperature, indicating the presence of source intrinsic processes such as particle acceleration.
Sara Issaoun 1,2 , Dominic W. Pesce 1,2 , María J. Rioja 3,4 , Richard Dodson 3 , Lindy Blackburn 1,2 , Garrett K. Keating 1
Sheperd S. Doeleman 1,2 , Bong Won Sohn 5 , Wu Jiang (江悟) 6 , Dan Hoak 7 , Wei Yu (于威) 1 , Pablo Torne 8 ,
Ramprasad Rao 1 , Remo P. J. Tilanus 9 , Iván Martí-Vidal 10,11 , Taehyun Jung 5 , Garret Fitzpatrick 1 ,
Miguel Sánchez-Portal 8 , Salvador Sánchez 8 , Jonathan Weintroub 1 , Mark Gurwell 1 , Carsten Kramer 12 , Carlos Durán 8
David John 8 , Juan L. Santaren 8 , Derek Kubo 13 , Chih-Chiang Han 14 , Helge Rottmann 15 , Jason SooHoo 7 , Vincent L. Fish 7
Guang-Yao Zhao 15 , Juan Carlos Algaba 16 , Ru-Sen Lu (路如森) 6,15,17 , Ilje Cho 5,18 , Satoki Matsushita 14 , and
Karl-Friedrich Schuster 12
Affiliation:
1
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA; sara.issaoun@cfa.harvard.edu
2
Black Hole Initiative, Harvard University, 20 Garden Street, Cambridge, MA 02138, USA
3
International Centre for Radio Astronomy Research, M468, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
4
Observatorio Astronómico Nacional (IGN), Alfonso XII, 3 y 5, 28014 Madrid, Spain
5
Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
6
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China
7
Massachusetts Institute of Technology, Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA
8
Institut de Radioastronomie Millimétrique (IRAM), Avenida Divina Pastora 7, Local 20, E-18012, Granada, Spain
9
University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
10
Departament d’Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, E-46100 Burjassot, València, Spain
11
Observatori Astronòmic, Universitat de València, C. Catedrático José Beltrán 2, E-46980 Paterna, València, Spain
12
Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d’Hères, France
13
Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. A’ohoku Place, Hilo, HI 96720, USA
14
Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Road, Taipei 106216,
Taiwan, R.O.C.
15
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
16
Department of Physics, Faculty of Science, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
17
Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing, 100101, People’s Republic of
China
18
Department of Astronomy, Yonsei University, Yonsei-ro 50, Seodaemun-gu, 03722 Seoul, Republic of Korea
Abstract:
Frequency phase transfer (FPT) is a technique designed to increase coherence and sensitivity in radio
interferometry by making use of the nondispersive nature of the troposphere to calibrate high-frequency data using
solutions derived at a lower frequency. While the Korean very long baseline interferometry (VLBI) network has
pioneered the use of simultaneous multiband systems for routine FPT up to an observing frequency of 130 GHz,
this technique remains largely untested in the (sub)millimeter regime. A recent effort has been made to outfit dual-
band systems at (sub)millimeter observatories participating in the Event Horizon Telescope (EHT) and to test the
feasibility and performance of FPT up to the observing frequencies of the EHT. We present the results of
simultaneous dual-frequency observations conducted in 2024 January on an Earth-sized baseline between the
IRAM 30-m in Spain and the James Clerk Maxwell Telescope (JCMT) and Submillimeter Array (SMA) in
Hawai‘i. We performed simultaneous observations at 86 and 215 GHz on the bright sources J0958+6533 and
OJ 287, with strong detections obtained at both frequencies. We observe a strong correlation between the
interferometric phases at the two frequencies, matching the trend expected for atmospheric fluctuations and
demonstrating for the first time the viability of FPT for VLBI at a wavelength of ∼1 millimeter. We show that the
application of FPT systematically increases the 215 GHz coherence on all averaging timescales. In addition, the use
of the colocated JCMT and SMA as a single dual-frequency station demonstrates the feasibility of paired-antenna
FPT for VLBI for the first time, with implications for future array capabilities (e.g., Atacama Large Millimeter/
submillimeter Array subarraying and ngVLA calibration strategies).
Huan-Xue Feng (冯焕雪) 1
1
, Jun-ichi Nakashima (中岛淳一) 1,2 , D. Engels 3 , S. Etoka 4 , Jaeheon Kim 5
(张泳) 1,2 , Jia-Yong Xie (谢嘉泳) 1 , and Jian-Jie Qiu (邱建杰) 1,2,6
Affiliation:
School of Physics and Astronomy, Sun Yat-sen University, Tang Jia Wan, Zhuhai 519082, People’s Republic of China; junichin@mail.sysu.edu.cu
CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area, Sun Yat-Sen University, 2 Duxue Road, Zhuhai 519082, Guangdong Province,
People’s Republic of China
3
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
4
Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, M13 9PL, UK
5
Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea
6
School of Mathematics and Physics, Jinggangshan University, 28 Xueyuan Road, Qingyuan District, Ji’an 343009, Jiangxi Province, People’s Republic of China
Abstract:
IRAS source 19312+1950 (hereafter I19312) is an infrared point source with maser emissions of SiO, H2O, and OH molecules. Although initial observations suggested that I19312 might be an evolved star, its characteristics are not fully consistent with this classification. This study aims to further investigate the nature of I19312 by conducting long-term monitoring of its maser emissions and comparing the results with other known astrophysical objects. We conducted long-term monitoring of SiO, H2O, and OH maser emissions using single-dish radio telescopes. The results were then compared with historical maser data and the characteristics of similar objects to infer the possible origin of I19312. The SiO maser emissions from I19312 were detected over a wide velocity range and exhibited significant time variability. The OH maser lines suggest characteristics of an evolved star, while the H2O maser lines indicate molecular outflows. These features suggest that I19312 could be a candidate for a water fountain star, though there are inconsistencies, such as the large molecular gas mass, that challenge this hypothesis. The possibility of I19312 being a red nova remnant (RNR) is also considered, but this remains speculative due to the lack of direct evidence. The evolutionary stage of I19312 remains unclear, but it shares multiple characteristics with both evolved stars with peculiar properties and RNRs. Further long-term monitoring and high-resolution interferometric observations are required to better constrain the nature of this object.
Ilje Cho 1,2,3,⋆ , Jongho Park 4,5 , Do-Young Byun 1,6 , Taehyun Jung 1 ,
Lindy Blackburn 7,8 , Freek Roelofs 9 , Andrew Chael 10 , Dominic W. Pesce 7,8 ,
Sheperd S. Doeleman 7,8 , Sara Issaoun 7,† , Jae-Young Kim 11,12 , Junhan Kim 13 ,
José L. Gómez 3 , Keiichi Asada 5 , Bong Won Sohn 1,6 , Sang-Sung Lee 1,6 ,
Jongsoo Kim 1 , Sascha Trippe 14,15 , and Aeree Chung 2
Affiliation:
1
Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
Department of Astronomy, Yonsei University, Seoul 03722, Republic of Korea
3
Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain
4
School of Space Research, Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
5
Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan, R. O. C.
6
University of Science and Technology (UST), Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea
7
Center for Astrophysics | Harvard & Smithsonian, Cambridge, MA 02138, USA
8
Black Hole Initiative, Harvard University, Cambridge, MA 02138, USA
9
Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University,
6500 GL Nijmegen, The Netherlands
10
Princeton Gravity Initiative, Princeton University, Jadwin Hall, Princeton, NJ 08544, USA
11
Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
12
Max Planck Institute for Radio Astronomy, D-53121 Bonn, Germany
13
Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
14
Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
15
SNU Astronomy Research Center (SNUARC), Seoul National University, Seoul 08826, Republic of Korea
†
NASA Hubble Fellowship Program, Einstein Fellow
Abstract:
The Event Horizon Telescope (EHT) has successfully revealed the shadow of the supermassive black hole, M87*, with an unprecedented angular resolution of approximately 20 μas at 230 GHz. However, because of limited short baseline lengths, the EHT has been constrained in its ability to recover larger-scale jet structures. The extended Korean VLBI Network (eKVN) is committed to joining the EHT from 2024 that can improve short baseline coverage. This study evaluates the impact of the participation of eKVN in the EHT on the recovery of the M87* jet. Synthetic data, derived from a simulated M87* model, were observed using both the EHT and the combined EHT+eKVN arrays, followed by image reconstructions from both configurations. The results indicate that the inclusion of eKVN significantly improves the recovery of jet structures by reducing residual noise. Furthermore, jackknife tests, in which one or two EHT telescopes were omitted？simulating potential data loss due to poor weather？demonstrate that eKVN effectively compensates for these missing telescopes, particularly in short baseline coverage. Multi-frequency synthesis imaging at 86？230 GHz shows that the EHT+eKVN array enhances the recovered spectral index distribution compared to the EHT alone and improves image reconstruction at each frequency over single-frequency imaging. As the EHT continues to expand its array configuration and observing capabilities to probe black hole physics more in depth, the integration of eKVN into the EHT will significantly enhance the stability of observational results and improve image fidelity. This advancement will be particularly valuable for future regular monitoring observations, where consistent data quality is essential.
1
Division of Science, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; yuhei.iwata@nao.ac.jp
Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan
3
Graduate School of Science and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-city, Yamaguchi 753-8512, Japan
4
Institute of Astronomy and Astrophysics, Academia Sinica, No.1, Sec. 4, Roosevelt Road, Taipei 106216, Taiwan
5
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
6
Center for Astronomy, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
7
Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
8
Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501, Japan
9
School of Physics and Astronomy, Faculty of Science, Monash University, Clayton, Victoria 3800, Australia
10
The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-city, Yamaguchi 753-8511, Japan
11
Astronomy Program, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea
12
Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea
Abstract:
We report on radio follow-up observations of the nearby Type II supernova SN 2023ixf, spanning from 1.7 to
269.9 days after the explosion, conducted using three very long baseline interferometers (VLBIs), which are the
Japanese VLBI Network, the VLBI Exploration of Radio Astrometry, and the Korean VLBI Network. In three
observation epochs (152.3, 206.1, and 269.9 days), we detected emission at the 6.9 and 8.4 GHz bands, with a flux
density of ~5 mJy. The flux density reached a peak at around 206.1 days, which is longer than the timescale to
reach the peak observed in typical Type II supernovae. Based on an analytical model of radio emission, our late-
time detections were inferred to be due to decreasing optical depth. In this case, the mass-loss rate of the progenitor
is estimated to have increased from ~10 −6 –10 −5 M e yr −1 to ~10 −4 M e yr −1 between 28 and 6 yr before the
explosion. Our radio constraints are also consistent with the mass-loss rate needed to produce a confined
circumstellar medium proposed by previous studies, which suggest that the mass-loss rate increased from
~10 −4 M e yr −1 to 10 −2 M e yr −1 in the last few years before the explosion.
Mikhail Lisakov 1,2,3,? , Svetlana Jorstad 4,5 , Maciek Wielgus 6,2 , Evgeniya V. Kravchenko 3,7 ,
Aleksei S. Nikonov 2 , Ilje Cho 8,9,6 , Sara Issaoun 10,?? , Juan-Carlos Algaba 11 , Thomas P. Krichbaum 2 ,
Uwe Bach 2 , Eduardo Ros 2 , Helge Rottmann 2 , Salvador Sánchez 12 , Jan Wagner 2 , and Anton Zensus 2
Affiliation:
1 Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
3 Astro Space Center, Lebedev Physical Institute, Profsouznaya 84/32, Moscow 117997, Russia
4 Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
5 Saint Petersburg State University, Universitetskaya Nab. 7-9, St. Petersburg 199034, Russia
6 Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain
7 Moscow Institute of Physics and Technology, Institutsky Per. 9, Moscow Region, Dolgoprudny 141700, Russia
8 Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea
9 Department of Astronomy, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 03722, Republic of Korea
10 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
11 Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
12 IRAM (Instituto de Radioastronomía Milimétrica), Avda. Divina Pastora 7, Local 20, 18012 Granada, Spain
Abstract:
Context.
The advancement of the Event Horizon Telescope has enabled the study of relativistic jets in active galactic nuclei down
to sub-parsec linear scales even at high redshift. Quasi-simultaneous multifrequency observations provide insights into the physical conditions in compact regions and allow accretion theories to be tested.
Aims. Initially, we aimed to measure the magnetic field strength close to the central supermassive black hole in NRAO 530 (1730−130) by studying the frequency-dependent opacity of the jet matter, Faraday rotation, and the spectral index in the millimeter-radio bands.
Methods.
NRAO 530 was observed quasi-simultaneously at 15, 22, 43, 86, and 227 GHz at four different very long baseline interfer-
ometer (VLBI) networks. By means of imaging and model-fitting, we aligned the images, taken at different frequencies. We explored opacity along the jet and the distribution of the linearly polarized emission in it.
Results.
Our findings reveal that the jet of NRAO 530 at 86 and 227 GHz is transparent down to its origin, with 70 mJy emission
detected at 227 GHz potentially originating from the accretion disk. The magnetic field strength near the black hole, estimated at 5r g , is 3 × 10 3 −3 × 10 4 G (depending on the central black hole mass). These values represent some of the highest magnetic field strengths reported for active galaxies. We also report the first ever VLBI measurement of the Faraday rotation at 43−227 GHz, which reveals rotation measure values as high as −48 000 rad/m 2 , consistent with higher particle density and stronger magnetic fields at the jet’s outset. The complex shape of the jet in NRAO 530 is in line with the expected behavior of a precessing jet, with a period estimated to be around 6 ± 4 years.
Spiral arm, rotating structure, and outflow cavity in massive star-forming region G23.43 −0.18
Authors:
James O. Chibueze , 1 , 2 ‹ Chukwuebuka J. Ugwu , 1 , 2 Tomoya Hirota, 3 , 4 Kee-Tae Kim, 5 , 6 Tie Liu, 7
Jakobus M. Vorster, 8 , 9 Ji-hyun Kang, 5 Jungha Kim, 5 , 10 Ross A. Burns, 11 Andrey M. Sobolev , 6 , 12
Jihye Hwang , 5 Chang Won Lee, 5 , 13 Mi Kyoung Kim 14 and Koichiro Sugiyama 15 , 16
Affiliation:
1 Department
of Mathematical Sciences, University of South Africa, Cnr Christian de Wet Rd and Pioneer Avenue, Florida Park, 1709 Roodepoort, South Africa
2 Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Carver Building, 1 University Road, Nsukka 410001, Nigeria
3 National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan
4 SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
5 Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong, Daejeon 34055, Korea
6 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, P. R. China
7 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, P. R. China
8 Centre for Space Research, North-West University, Potchefstroom 2520, South Africa
9 Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland
10 Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134, Korea
11 RIKEN, Cluster for Pioneering Research, Wako-shi, Saitama, Japan
12 Astronomical Observatory, Institute for Natural Sciences and Mathematics, Ural Federal University, 19 Mira Street, Ekaterinburg 620002, Russia
13 University of Science and Technology, Korea (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
14 Department of Child Studies, Faculty of Home Economics, Otsuma Women’s University, 12 Sanban-cho, Chiyoda-ku, Tokyo 102-8357, Japan
15 National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiang Mai 50180, Thailand
16 Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Abstract:
We confirmed the existence of a massive protocluster in G23.43 −0.18 from our Atacama Large Millimeter/submillimeter Array
(ALMA) 1.3 mm continuum and molecular line observations. We resolved the region into one main massive protostellar object,
G23.43 −0.18 A, one intermediate mass protostellar object, G23.43 −0.18 B, and three low mass objects, G23.43 −0.18 C1,
G23.43 −0.18 C2, and G23.43 −0.18 C3. A spiral arm structure is observed in G23.43 −0.18 B. G23.43 −0.18 A 1.3 mm dust
continuum emission showed a ‘butterfly’ morphology with clear evidence of the existence of a cavity and bipolar outflow with an
inclination angle of 50 ◦ . G23.43 −0.18 B presents a compact rotating structure, and possibly an inner Keplerian disc, traced with
methanol lines and powers a jet revealed by multiple compact emission peaks in CO, indicating episodic ejections every 300 yr.
The presence of 6.7 GHz methanol masers in G23.43 −0.18 A and G23.43 −0.18 B are strong indications that both objects host
massive protostars and are good sites to test some theories of the early evolutionary phases of massive stars.