☆ 4.0 Article

RadioAstron Science Program Five Years after Launch: Main Science Results

SOLAR SYSTEM RESEARCH (2017)

Journal

SOLAR SYSTEM RESEARCH

Volume 51, Issue 7, Pages 535-554

Publisher

MAIK NAUKA/INTERPERIODICA/SPRINGER

DOI: 10.1134/S0038094617070085

Keywords

ground-space interferometer; very long baseline interferometry (VLBI); active galactic nuclei (AGN); quasars; pulsars; cosmic masers; interstellar scattering

Categories

Astronomy & Astrophysics

Funding

Fundamental Research Program P-7 of the Presidium of the Russian Academy of Sciences (Subprogram Transition and Explosion Processes in Astrophysics)
Russian Foundation for Basic Research [13-02-12103]

Ask authors/readers for more resources

Protocol

Community support

Reagent

Community support

Abstract

The RadioAstron ground-space interferometer provides the highest angular resolution achieved now in astronomy. The detection of interferometric fringes from quasars with this angular resolution on baselines of 100-200 thousand km suggests the brightness temperatures which exceed the Compton limit by two orders of magnitude. Polarimetric measurements on ground-space baselines have revealed fine structure testifying to recollimation shocks on scales of 100-250 mu as and a helical magnetic field near the base of radio emission in BL Lacertae. Substructure within a the scattering disk of pulsar emission on interferometer baselines (from 60000 to 250000 km) was discovered. This substructure is produced by action of the interstellar interferometer with an effective baseline of about 1 AU and the effective angular resolution of better than 1 mu as. Diameters of scattering disks were measured for several pulsars, and distances to diffusing screens were evaluated. The ground-space observations of sources of the maser radiation in lines of water and hydroxyl have shown that the maser sources in star-forming regions remain unresolved on baselines, which considerably exceed the Earth diameter. These very compact and bright features with angular sizes of about 20-60 mu as correspond to linear sizes of about 5-10 million km (several solar diameters).

Authors

I am an author on this paper

Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.0

Not enough ratings

Secondary Ratings

Novelty

-

Significance

-

Scientific rigor

-

Rate this paper

Recommended

Article Astronomy & Astrophysics

Cosmic-ray driven galactic winds from the warm interstellar medium

Shaunak Modak, Eliot Quataert, Yan-Fei Jiang, Todd A. Thompson

Summary: We have studied cosmic-ray driven galactic winds from the warm interstellar medium using simulations. The model includes radiative cooling and CR-streaming-mediated heating of the gas. The simulations show that a thermally unstable equilibrium leads to a multiphase wind with fluctuations in density and temperature. The results suggest that the preventive CR feedback is inefficient in the physical conditions modeled here.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Astronomy & Astrophysics

BAT AGN Spectroscopic Survey XXVII: scattered X-Ray radiation in obscured active galactic nuclei

K. K. Gupta, C. Ricci, A. Tortosa, Y. Ueda, T. Kawamuro, M. Koss, B. Trakhtenbrot, K. Oh, F. E. Bauer, F. Ricci, G. C. Privon, L. Zappacosta, D. Stern, D. Kakkad, E. Piconcelli, S. Veilleux, R. Mushotzky, T. Caglar, K. Ichikawa, A. Elagali, M. C. Powell, C. M. Urry, F. Harrison

Summary: The study examines the properties of the scattered component for nearby obscured AGN, finding significant negative correlation between scattering fraction and column density, as well as positive correlation with the ratio of [OIII] lambda 5007 to X-ray luminosity. These findings suggest possible relationships between different physical properties of AGN and the Thomson-scattered component associated with the narrow-line region.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2021)

Add to Collection

Article Astronomy & Astrophysics

Using interstellar clouds to search for Galactic PeVatrons: gamma-ray signatures from supernova remnants

A. M. W. Mitchell, G. P. Rowell, S. Celli, S. Einecke

Summary: The study identifies the necessary properties of interstellar clouds and accelerators, produces a ranked shortlist of promising target systems, discusses detection prospects for future facilities, and finds that larger, closer, slightly older interstellar clouds are more likely to produce detectable gamma-ray fluxes.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2021)

Add to Collection

Article Astronomy & Astrophysics

HD molecules at high redshift: cosmic ray ionization rate in the diffuse interstellar medium

D. N. Kosenko, S. A. Balashev, P. Noterdaeme, J-K Krogager, R. Srianand, C. Ledoux

Summary: A systematic study of deuterated molecular hydrogen (HD) at high redshift reveals new HD lines associated with known Damped Lyman-alpha systems and measures upper limits on column density. The new detections have similar ratios to previous findings, showing marked differences with measurements in the Galaxy, likely due to varying physical conditions and metallicity between local and high-redshift interstellar media. Cosmic ray ionization rate (CRIR, zeta) shows significant dispersion from a few x 10(-18) s(-1) to a few x 10(-15) s(-1), strongly correlating with UV flux (chi) and showing a physical connection with star-forming regions.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2021)

Add to Collection

Article Astronomy & Astrophysics

Deep learning models of the discrete component of the Galactic interstellar ?-ray emission

Alexander Shmakov, Mohammadamin Tavakoli, Pierre Baldi, Christopher M. Karwin, Alex Broughton, Simona Murgia

Summary: Researchers use convolutional neural networks to predict the emission of rare gas tracers in the gamma-ray radiation, which is not observed, in order to better distinguish between gamma-ray sources and interstellar gas, and to accurately define the characteristics of gamma-ray sources. This method can effectively model in data-rich regions and has the potential to be applied in unobserved regions.

PHYSICAL REVIEW D (2023)

Add to Collection

Article Chemistry, Analytical

Radio Astronomical Antennas in the Central African Region to Improve the Sampling Function of the VLBI Network in the SKA Era?

Marcellin Atemkeng, Patrice Okouma, Eric Maina, Roger Ianjamasimanana, Serges Zambou

Summary: South Africa has world-class astronomical facilities and its Square Kilometre Array project has attracted six African countries to join in building the African Very Long Baseline Interferometry Network. This study analyzes the impact of adding radio telescopes in central African countries on scientific research and discusses the economic and human capital impacts of radio interferometers in central Africa.

SENSORS (2022)

Add to Collection

Article Astronomy & Astrophysics

The SOUX AGN sample: SDSS-XMM-Newton optical, ultraviolet, and X-ray selected active galactic nuclei spanning a wide range of parameter space - sample definition

Daniel Kynoch, Jake A. J. Mitchell, Martin J. Ward, Chris Done, Elisabeta Lusso, Hermine Landt

Summary: We collect a sample of 696 type 1 active galactic nuclei (AGN) with redshifts up to z = 2.5, all of which have specific spectroscopic and photometric data. The black hole mass relations for three emission lines are determined and found to provide consistent mass estimates. The variations of UV/X-ray energy index alpha(ox) with UV continuum luminosity and black hole properties are explored, showing differences between narrow/broad-line and radio-loud/quiet subsets of AGN.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Astronomy & Astrophysics

The Galactic Interstellar Medium Has a Preferred Handedness of Magnetic Misalignment

Zhiqi Huang

Summary: The Planck mission detected a positive correlation between the intensity and B-mode polarization of the Galactic thermal dust emission. Recent work has shown evidence that this correlation is caused by the misalignment between dust filaments and the sky-projected magnetic field. However, it is unclear whether this correlation is due to statistical fluctuations or some parity-violating physics. This study uses simulations to quantify the statistical fluctuation interpretation and finds a significant tension between the Planck data and the simulated distribution.

UNIVERSE (2022)

Add to Collection

Article Astronomy & Astrophysics

Exploring Gravitationally Lensed z ≳ 6 X-Ray Active Galactic Nuclei Behind the RELICS Clusters

Akos Bogdan, Orsolya E. Kovacs, Christine Jones, William R. Forman, Ralph P. Kraft, Victoria Strait, Dan Coe, Marusa Bradac

Summary: Observations of high-redshift galaxies provide insights into the properties of black holes formed after the Big Bang, but the origin of the first black holes remains unknown. This study uses gravitational lensing to study the X-ray emissions of 155 high-redshift galaxies and does not find a definitive association with X-ray sources. A statistically significant detection is found for massive galaxies, but no detection is found for other galaxy samples.

ASTROPHYSICAL JOURNAL (2022)

Add to Collection

Article Astronomy & Astrophysics

High-energy Neutrino Emission from Espresso-reaccelerated Ions in Jets of Active Galactic Nuclei

Rostom Mbarek, Damiano Caprioli, Kohta Murase

Summary: We calculate the flux of ultrahigh-energy cosmic rays (UHECRs) and high-energy neutrinos produced by active galactic nuclei (AGNs) using 3D relativistic magnetohydrodynamic jet simulations. We find that UHECRs in AGN jets are not significantly affected by photodisintegration, consistent with observations favoring a heavy composition at the highest energies. We also estimate the flux of high-energy neutrinos from AGN jets and find that these neutrinos may account for a sizable fraction of the expected flux, but cannot fully explain the observed flux. Our results suggest that nearby radio galaxies may be more promising as potential sources of UHECRs and neutrinos.

ASTROPHYSICAL JOURNAL (2023)

Add to Collection

Article Astronomy & Astrophysics

Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. V. Space and Ground Millimeter-VLBI Imaging of OJ 287

Jose L. Gomez, Efthalia Traianou, Thomas P. Krichbaum, Andrei P. Lobanov, Antonio Fuentes, Rocco Lico, Guang-Yao Zhao, Gabriele Bruni, Yuri Y. Kovalev, Anne Lahteenmaki, Petr A. Voitsik, Mikhail M. Lisakov, Emmanouil Angelakis, Uwe Bach, Carolina Casadio, Ilje Cho, Lankeswar Dey, Achamveedu Gopakumar, Leonid Gurvits, Svetlana Jorstad, Yuri A. Kovalev, Matthew L. Lister, Alan P. Marscher, Ioannis Myserlis, Alexander B. Pushkarev, Eduardo Ros, Tuomas Savolainen, Merja Tornikoski, Mauri J. Valtonen, Anton Zensus

Summary: The first polarimetric space VLBI observations of OJ 287 reveal the high angular resolution and bending features of the innermost jet, consistent with predictions from a supermassive binary black hole model and equipartition between particles and magnetic field on parsec scales.

ASTROPHYSICAL JOURNAL (2022)

Add to Collection

Article Astronomy & Astrophysics

A Catalog of 204 Offset and Dual Active Galactic Nuclei (AGNs): Increased AGN Activation in Major Mergers and Separations under 4 kpc

Aaron Stemo, Julia M. Comerford, R. Scott Barrows, Daniel Stern, Roberto J. Assef, Roger L. Griffith, Aimee Schechter

Summary: The study reveals that the fraction of AGNs peaks at SMBH pair separations <10 kpc and significantly increases at separations of <4 kpc; AGNs in mergers are more commonly found in major mergers, with the fraction decreasing as the merger mass ratio increases. Mergers do not trigger the most luminous AGNs, and factors such as nuclear column density, AGN luminosity, and host galaxy star formation rate show no dependence on SMBH pair separation or merger mass ratio.

ASTROPHYSICAL JOURNAL (2021)

Add to Collection

Article Astronomy & Astrophysics

On the Origin of Radio-loudness in Active Galactic Nuclei Using Far-infrared Polarimetric Observations

Enrique Lopez-Rodriguez, Makoto Kishimoto, Robert Antonucci, Mitchell C. Begelman, Noemie Globus, Roger Blandford

Summary: The dichotomy between radio-loud and radio-quiet active galactic nuclei is likely due to the presence of a strong magnetic field that enhances or causes accretion and jet power. The polarized dust emission cores of RL and RQ AGNs were measured, showing that RL AGNs have polarized cores while RQ AGNs do not. This indicates that the size and strength of the B-fields surrounding AGNs are related to the strength of the jet power.

ASTROPHYSICAL JOURNAL (2023)

Add to Collection

Article Astronomy & Astrophysics

A New Iron Emission Template for Active Galactic Nuclei. I. Optical Template for the Hβ Region*

Daeseong Park, Aaron J. Barth, Luis C. Ho, Ari Laor

Summary: We present a new empirical template for iron emission in active galactic nuclei, which provides a better fit and more accurate spectral measurements compared to widely used templates. The choice of iron template can introduce a systematic bias that affects black hole mass estimates.

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES (2022)

Add to Collection

Article Astronomy & Astrophysics

HyGAL: Characterizing the Galactic Interstellar Medium with Observations of Hydrides and Other Small Molecules. I. Survey Description and a First Look Toward W3(OH), W3 IRS5, and NGC 7538 IRS1

A. M. Jacob, D. A. Neufeld, P. Schilke, H. Wiesemeyer, W-J Kim, S. Bialy, M. Busch, D. Elia, E. Falgarone, M. Gerin, B. Godard, R. Higgins, P. Hennebelle, N. Indriolo, D. C. Lis, K. M. Menten, A. Sanchez-Monge, T. Moeller, V Ossenkopf-Okada, M. R. Rugel, D. Seifried, P. Sonnentrucker, S. Walch, M. G. Wolfire, F. Wyrowski, V. Valdivia

Summary: The HyGAL program surveys multiple hydride molecules and atomic constituents in the interstellar medium to address questions related to the life cycle of molecular material and the phase transition from atomic to molecular gas. The observations provide valuable insights into the distribution and behavior of these species, serving as an important legacy for future ISM studies.

ASTROPHYSICAL JOURNAL (2022)

Add to Collection

Article Astronomy & Astrophysics

Multi-frequency VLBI observations of maser lines during the 6.7 GHz maser flare in the high-mass young stellar object G24.33+0.14

A. Kobak, A. Bartkiewicz, M. Szymczak, M. Olech, M. Durjasz, P. Wolak, J. O. Chibueze, T. Hirota, J. Eisloffel, B. Stecklum, A. Sobolev, O. Bayandina, G. Orosz, R. A. Burns, K. -T. Kim, S. P. van den Heever

Summary: Recent studies have shown that 6.7 GHz methanol maser flares can verify maser production mechanisms and specific characteristics of high-mass star formation. In this study, the 6.7 and 12.2 GHz methanol masers and 22.2 GHz water vapor masers of the high-mass young stellar object G24.33+0.14 were monitored using VLBA. The correlation between the 6.7 GHz maser and infrared fluxes was found using WISE data. The results indicate that the maser morphology remains stable during the monitoring period, possibly due to recurring low-energy accretion events.

ASTRONOMY & ASTROPHYSICS (2023)

Add to Collection

Article Astronomy & Astrophysics

Time variability of the core-shift effect in the blazar 3C 454.3

Wara Chamani, Tuomas Savolainen, Eduardo Ros, Yuri Y. Kovalev, Kaj Wiik, Anne Laehteenmaeki, Merja Tornikoski, Joni Tammi

Summary: Measuring and inferring the key physical parameters of jets in active galactic nuclei (AGN) requires high-resolution very long baseline interferometry (VLBI) observations. Using VLBI to measure a core-shift effect is a common way of obtaining estimates of the jet magnetic field strength, but the measured core shift can vary over time. In this study, we found significant core-shift variability in the luminous blazar 3C 454.3, and also observed time variability of the core-shift index. However, when selecting epochs where the core-shift index is 1, the magnetic field estimates are consistent.

ASTRONOMY & ASTROPHYSICS (2023)

Add to Collection

Article Astronomy & Astrophysics

Nature of continuum emission in the source of the water maser super-flare G25.65+1.04

O. S. Bayandina, R. A. Burns, S. E. Kurtz, L. Moscadelli, A. M. Sobolev, B. Stecklum, I. E. Val'tts

Summary: The G25.65+1.04 source is a poorly studied 'super-flare' water maser in the Milky Way. By examining the parameters of the continuum sources and their association with different types of masers, this study aims to clarify the composition and properties of the G25.65+1.04 region. The results show that the source driving the water maser is most likely a protostar in an early stage of evolution, and there are active accretion and ejection processes happening in the region.

ASTRONOMY & ASTROPHYSICS (2023)

Add to Collection

Article Astronomy & Astrophysics

The Event Horizon Telescope Image of the Quasar NRAO 530

Svetlana Jorstad, Maciek Wielgus, Rocco Lico, Sara Issaoun, Avery E. Broderick, Dominic W. Pesce, Jun Liu, Guang-Yao Zhao, Thomas P. Krichbaum, Lindy Blackburn, Chi-kwan Chan, Michael Janssen, Venkatessh Ramakrishnan, Kazunori Akiyama, Antxon Alberdi, Juan Carlos Algaba, Katherine L. Bouman, Ilje Cho, Antonio Fuentes, Jose L. Gomez, Mark Gurwell, Michael D. Johnson, Jae-Young Kim, Ru-Sen Lu, Ivan Marti-Vidal, Monika Moscibrodzka, Felix M. Poetzl, Efthalia Traianou, Ilse van Bemmel, Walter Alef, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Raymond Blundell, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gomez-Ruiz, Minfeng Gu, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, David J. James, Buell T. Jannuzi, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Abhishek V. Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Shoko Koyama, Carsten Kramer, Michael Kramer, Cheng-Yu Kuo, Noemi La Bella, Tod R. Lauer, Daeyoung Lee, Sang-Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Daniel Michalik, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Cornelia Mueller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Junghwan Oh, Hiroki Okino, Hector Olivares, Gisela N. Ortiz-Leon, Tomoaki Oyama, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Vincent Pietu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Jorge A. Preciado-Lopez, Dimitrios Psaltis, Hung-Yi Pu, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Angelo Ricarte, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sanchez, David Sanchez-Arguelles, Miguel Sanchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Pablo Torne, Tyler Trent, Sascha Trippe, Matthew Turk, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Kaj Wiik, Gunther Witzel, Michael F. Wondrak, George N. Wong, Qingwen Wu, Paul Yamaguchi, Doosoo Yoon, Andre Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Shan-Shan Zhao

Summary: This study reports on the observations of quasar NRAO 530 with the Event Horizon Telescope, which produced the first image of the most distant object observed by EHT to date. The image shows a bright feature with linear polarization at the core of the quasar, revealing a helical magnetic field structure in the jet.

ASTROPHYSICAL JOURNAL (2023)

Add to Collection

Article Astronomy & Astrophysics

Comparison of Polarized Radiative Transfer Codes Used by the EHT Collaboration

Ben S. Prather, Jason Dexter, Monika Moscibrodzka, Hung-Yi Pu, Thomas Bronzwaer, Jordy Davelaar, Ziri Younsi, Charles F. Gammie, Roman Gold, George N. Wong, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi A. Bauboeck, Bradford Benson, Dan Bintley, Lindy Blackburn, Raymond L. Blundell, Katherine C. Bouman, Geoffrey Bower, Hope Boyce, Michael D. Bremer, Christiaan Brinkerink, Roger Brissenden, Silke E. Britzen, Avery Broderick, Dominique Broguiere, Sandra Bustamante, Do-Young E. Byun, John Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan O. Chan, Dominic Chang, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre S. Christian, Nicholas E. Conroy, John M. Conway, James M. Cordes, Thomas B. Crawford, Geoffrey Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Vedant S. Dhruv, Sheperd Doeleman, Sean A. Dougal, Sergio P. Dzib, Ralph Eatough, Razieh Emami, Heino Falcke, Joseph L. Farah, Vincent Fish, Ed Fomalont, H. Alyson Ford, Raquel T. Fraga-Encinas, William Freeman, Per M. Friberg, Christian Fromm, Antonio Fuentes, Peter Galison, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco I. Goddi, Arturo Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari H. Haworth, Michael Hecht, Ronald Hesper, Dirk C. Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei H. Huang, David Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara J. Issaoun, David T. James, Buell Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra D. Jimenez-Rosales, Michael Johnson, Svetlana V. Jorstad, Abhishek Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa K. Kawashima, Garrett Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Shoko Koyama, Carsten Kramer, Michael P. Kramer, Thomas Krichbaum, Cheng-Yu Kuo, Noemi R. La Bella, Tod Lauer, Daeyoung Lee, Sang-Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping P. Lo, Andrei Lobanov, Laurent J. Loinard, Colin Lonsdale, Ru-Sen R. Lu, Nicholas MacDonald, Jirong Mao, Nicola Marchili, Sera P. Markoff, Daniel P. Marrone, Alan Marscher, Ivan Marti-Vidal, Satoki D. Matsushita, Lynn Matthews, Lia M. Medeiros, Karl Menten, Daniel Michalik, Izumi Mizuno, Yosuke M. Mizuno, James Moran, Kotaro Moriyama, Cornelia Mueller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi M. Nagai, Neil Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis A. Noutsos, Michael Nowak, Junghwan Oh, Hiroki Okino, Hector N. Olivares, Gisela Ortiz-Leon, Tomoaki Oyama, Feryal oezel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li W. Pen, Dominic Pesce, Vincent Pietu, Richard Plambeck, Aleksandar PopStefanija, Oliver M. Porth, Felix A. Poetzl, Jorge Preciado-Lopez, Dimitrios Psaltis, Venkatessh Ramakrishnan, Ramprasad G. Rao, Mark W. Rawlings, Alexander Raymond, Luciano Rezzolla, Angelo Ricarte, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge L. Rottmann, Alan Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sanchez, David Sanchez-Argueelles, Miguel Sanchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, He Sun, Fumie J. Tazaki, Alexandra Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Huib Jan R. van Langevelde, Daniel van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, Kaj Wiik, Gunther F. Witzel, Michael Wondrak, Qingwen Wu, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andre Young, Ken Young, Wei Yu, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, Shan-Shan Zhao

Summary: Interpretation of resolved polarized images of black holes by the EHT relies on predicting the polarized emission observable by Earth-based instruments for a specific black hole accretion model. GRRT codes used within the EHT Collaboration are evaluated for accuracy and consistency in producing test images, demonstrating high consistency in various methods and implementations of radiative transfer calculations. The comparison shows similar images with a pixel-wise normalized mean squared error (NMSE) of 0.012 for an analytic accretion model, and NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U, and V for a cell-based magnetohydrodynamic simulation snapshot. The agreement between the image metrics and published EHT results is better than measurement uncertainties.

ASTROPHYSICAL JOURNAL (2023)

Add to Collection

Article Astronomy & Astrophysics

MOJAVE - XXI. Decade-long linear polarization variability in AGN jets at parsec scales

D. Zobnina, H. D. Aller, M. F. Aller, D. C. Homan, Y. Y. Kovalev, M. L. Lister, I. N. Pashchenko, A. B. Pushkarev, T. Savolainen

Summary: Using stacking of images obtained at different epochs, we analyzed the variability properties of AGN jets on parsec-scales. Our sample consists of 436 core-jet AGNs with at least 5 VLBA observing epochs from 1996 to 2019. We found that core EVPA variability is typically higher than that of the jet and BL Lacertae object cores have lower EVPA variability compared to quasars.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Astronomy & Astrophysics

MOJAVE - XX. Persistent linear polarization structure in parsec-scale AGN jets

A. B. Pushkarev, H. D. Aller, M. F. Aller, D. C. Homan, Y. Y. Kovalev, M. L. Lister, I. N. Pashchenko, T. Savolainen, D. Zobnina

Summary: We analysed the parsec-scale linear polarization properties of 436 active galactic nuclei (AGNs) using VLBA observations and found the presence of large-scale helical magnetic fields associated with the outflow. In some AGN jets, we detected quasi-constant fractional polarization profiles and closely aligned EVPAs along the jet. BL Lacs showed higher fractional polarization values in their cores and jets compared to quasars, but became comparable on larger scales. High-synchrotron-peaked BL Lac jets had lower polarization compared to intermediate and low-synchrotron-peaked BL Lacs. The EVPAs in BL Lacs tended to align with the local jet direction, while quasars showed an excess of orthogonal polarization orientation.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Astronomy & Astrophysics

Growing evidence for high-energy neutrinos originating in radio blazars

A. Plavin, Y. Y. Kovalev, Yu A. Kovalev, S. Troitsky

Summary: Evidence has been found suggesting that bright-radio blazars are high-energy neutrino sources, but the specifics of their production and location are still unknown. This paper adds 14 new IceCube events from 2020-2022, updating the analysis of the neutrino-blazars connection. By correlating these events with a sample of 3412 extragalactic radio sources, the study confirms the statistical association between neutrinos and radio-bright blazars. Several new neutrino-blazar associations are also discovered and discussed, including those involving PKS 1741 - 038 and PKS 0735 + 168.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Multidisciplinary Sciences

A ring-like accretion structure in M87 connecting its black hole and jet

Ru-Sen Lu, Keiichi Asada, Thomas P. Krichbaum, Jongho Park, Fumie Tazaki, Hung-Yi Pu, Masanori Nakamura, Andrei Lobanov, Kazuhiro Hada, Kazunori Akiyama, Jae-Young Kim, Ivan Marti-Vidal, Jose L. Gomez, Tomohisa Kawashima, Feng Yuan, Eduardo Ros, Walter Alef, Silke Britzen, Michael Bremer, Avery E. Broderick, Akihiro Doi, Gabriele Giovannini, Marcello Giroletti, Paul T. P. Ho, Mareki Honma, David H. Hughes, Makoto Inoue, Wu Jiang, Motoki Kino, Shoko Koyama, Michael Lindqvist, Jun Liu, Alan P. Marscher, Satoki Matsushita, Hiroshi Nagai, Helge Rottmann, Tuomas Savolainen, Karl-Friedrich Schuster, Zhi-Qiang Shen, Pablo de Vicente, R. Craig Walker, Hai Yang, J. Anton Zensus, Juan Carlos Algaba, Alexander Allardi, Uwe Bach, Ryan Berthold, Dan Bintley, Do-Young Byun, Carolina Casadio, Shu-Hao Chang, Chih-Cheng Chang, Song-Chu Chang, Chung-Chen Chen, Ming-Tang Chen, Ryan Chilson, Tim C. Chuter, John Conway, Geoffrey B. Crew, Jessica T. Dempsey, Sven Dornbusch, Aaron Faber, Per Friberg, Javier Gonzalez Garcia, Miguel Gomez Garrido, Chih-Chiang Han, Kuo-Chang Han, Yutaka Hasegawa, Ruben Herrero-Illana, Yau-De Huang, Chih-Wei L. Huang, Violette Impellizzeri, Homin Jiang, Hao Jinchi, Taehyun Jung, Juha Kallunki, Petri Kirves, Kimihiro Kimura, Jun Yi Koay, Patrick M. Koch, Carsten Kramer, Alex Kraus, Derek Kubo, Cheng-Yu Kuo, Chao-Te Li, Lupin Chun-Che Lin, Ching-Tang Liu, Kuan-Yu Liu, Wen-Ping Lo, Li-Ming Lu, Nicholas MacDonald, Pierre Martin-Cocher, Hugo Messias, Zheng Meyer-Zhao, Anthony Minter, Dhanya G. Nair, Hiroaki Nishioka, Timothy J. Norton, George Nystrom, Hideo Ogawa, Peter Oshiro, Nimesh A. Patel, Ue-Li Pen, Yurii Pidopryhora, Nicolas Pradel, Philippe A. Raffin, Ramprasad Rao, Ignacio Ruiz, Salvador Sanchez, Paul Shaw, William Snow, T. K. Sridharan, Ranjani Srinivasan, Belen Tercero, Pablo Torne, Efthalia Traianou, Jan Wagner, Craig Walther, Ta-Shun Wei, Jun Yang, Chen-Yu Yu

Summary: Images of M87 obtained at a wavelength of 3.5 mm reveal a spatially resolved compact radio core with a ring-like structure. The ring has a diameter of 8.4 Schwarzschild radii, approximately 50% larger than the one observed at 1.3 mm. The presence of absorption effects suggests a substantial contribution from the accretion flow in addition to the gravitationally lensed emission.

NATURE (2023)

Add to Collection

Article Astronomy & Astrophysics

Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities

Sara Issaoun, Dominic W. Pesce, Freek Roelofs, Andrew Chael, Richard Dodson, Maria J. Rioja, Kazunori Akiyama, Romy Aran, Lindy Blackburn, Sheperd S. Doeleman, Vincent L. Fish, Garret Fitzpatrick, Michael D. Johnson, Gopal Narayanan, Alexander W. Raymond, Remo P. J. Tilanus

Summary: This paper argues for incorporating an additional 86 GHz observing band to enhance the utility and efficiency of the ngEHT. The reliably good weather conditions at the ngEHT sites enable year-round observations at 86 GHz. By including 86 GHz observations in multi-frequency imaging, the (u,v) coverage at 230 and 345 GHz can be sufficiently augmented to detect the M87 jet structure without requiring EHT stations to join the array. The ngEHT's general calibration and sensitivity can also be improved through simultaneous observations at 86 GHz and higher-frequency bands.

GALAXIES (2023)

Add to Collection

Article Astronomy & Astrophysics

Key Science Goals for the Next-Generation Event Horizon Telescope

Michael D. Johnson, Kazunori Akiyama, Lindy Blackburn, Katherine L. Bouman, Avery E. Broderick, Vitor Cardoso, Rob P. Fender, Christian M. Fromm, Peter Galison, Jose L. Gomez, Daryl Haggard, Matthew L. Lister, Andrei P. Lobanov, Sera Markoff, Ramesh Narayan, Priyamvada Natarajan, Tiffany Nichols, Dominic W. Pesce, Ziri Younsi, Andrew Chael, Koushik Chatterjee, Ryan Chaves, Juliusz Doboszewski, Richard Dodson, Sheperd S. Doeleman, Jamee Elder, Garret Fitzpatrick, Kari Haworth, Janice Houston, Sara Issaoun, Yuri Y. Kovalev, Aviad Levis, Rocco Lico, Alexandru Marcoci, Niels C. M. Martens, Neil M. Nagar, Aaron Oppenheimer, Daniel C. M. Palumbo, Angelo Ricarte, Maria J. Rioja, Freek Roelofs, Ann C. Thresher, Paul Tiede, Jonathan Weintroub, Maciek Wielgus

Summary: The Event Horizon Telescope (EHT) has produced the first images of supermassive black holes in the M87 galaxy and the Milky Way. The next-generation EHT (ngEHT) program aims to enhance the resolution, dynamic range, and temporal coverage of these observations, enabling groundbreaking discoveries in black hole science. The ngEHT and its instrument requirements have been formulated through a collaborative international effort involving hundreds of scientists.

GALAXIES (2023)

Add to Collection

Article Astronomy & Astrophysics

Search for directional associations between baikal gigaton volume detector neutrino-induced cascades and high-energy astrophysical sources

V. A. Allakhverdyan, A. D. Avrorin, A. Avrorin, V. M. Aynutdinov, Z. Bardacova, I. A. Belolaptikov, E. A. Bondarev, I. Borina, N. M. Budnev, A. S. Chepurnov, V. Y. Dik, G. Domogatsky, A. A. Doroshenko, R. Dvornicky, A. N. Dyachok, Zh-A M. Dzhilkibaev, E. Eckerova, T. Elzhov, L. Fajt, A. R. Gafarov, K. Golubkov, N. S. Gorshkov, T. Gress, K. G. Kebkal, I Kharuk, E. Khramov, M. M. Kolbin, K. Konischev, A. Korobchenko, A. P. Koshechkin, V. A. Kozhin, M. Kruglov, V. F. Kulepov, Y. E. Lemeshev, M. B. Milenin, R. R. Mirgazov, D. Naumov, A. S. Nikolaev, D. P. Petukhov, E. N. Pliskovsky, M. Rozanov, E. Ryabov, G. B. Safronov, D. Seitova, B. A. Shaybonov, M. D. Shelepov, S. D. Shilkin, E. Shirokov, F. Simkovic, A. E. Sirenko, A. Skurikhin, A. G. Solovjev, M. N. Sorokovikov, I Stekl, A. P. Stromakov, O. Suvorova, V. A. Tabolenko, B. B. Ulzutuev, Y. Yablokova, D. N. Zaborov, S. Zavyalov, D. Y. Zvezdov, N. A. Kosogorov, Y. Y. Kovalev, G. Lipunova, A. Plavin, D. Semikoz, S. Troitsky, Baikal GVD Collaboration

Summary: Baikal-GVD has published its first measurement of the diffuse astrophysical neutrino flux, and further explores the data set to identify possible associations with known astrophysical sources. They utilize a high-angular resolution neutrino telescope and liquid water as the detection medium to study the relationship between high-energy cascade events and astrophysical point sources. Though the current sample size is limited, their analysis suggests potential associations with extragalactic and Galactic sources.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY (2023)

Add to Collection

Article Astronomy & Astrophysics

Filamentary structures as the origin of blazar jet radio variability

Antonio Fuentes, Jose L. Gomez, Jose M. Marti, Manel Perucho, Guang-Yao Zhao, Rocco Lico, Andrei P. Lobanov, Gabriele Bruni, Yuri Y. Kovalev, Andrew Chael, Kazunori Akiyama, Katherine L. Bouman, He Sun, Ilje Cho, Efthalia Traianou, Teresa Toscano, Rohan Dahale, Marianna Foschi, Leonid I. Gurvits, Svetlana Jorstad, Jae-Young Kim, Alan P. Marscher, Yosuke Mizuno, Eduardo Ros, Tuomas Savolainen

Summary: This study presents high-resolution images of the blazar 3C 279 obtained with space very-long-baseline interferometry. The images reveal the transverse structure of the jet and several filaments produced by plasma instabilities. The study also proposes a new model to explain the radio variability of blazar jet.

NATURE ASTRONOMY (2023)

Add to Collection

No Data Available

© Peeref 2019-2024. All rights reserved.