Research Highlights
Here we show recent research results from the Radio Astronomy/Very-Long-Baseline Interferometry department.
Predicting Cherenkov telescope detections from Active Galactic Nuclei
14 October 2019
The MPIfR astronomer Roberto Angioni publishes today at the journal Astroparticle Physics a study of the detection prospects for the Cherenkov Telescope Array (CTA). By simulating observations of forty-one γ-ray radio galaxies, extrapolating their Fermi-LAT spectrum into the TeV energy range assuming different spectral shapes, the author predicts that the CTA will detect eleven new TeV radio galaxies with an observational campaign of fifty hours per source. This would increase the sample of very-high-energy radio galaxies by a factor of three. More details, in the original publication here.
Gamma-ray emission at 140 light years from the jet base in the quasar 3C 279
23 September 2019
An international team of astronomers, led by Víctor M. Patiño-Álvarez, affiliated to the MPI für Radioastronomie and now leader of a partner research group at the Mexican Instituto Nacional de Astrofísica Óptica y Electrónica in Puebla has presented a study of the radio-gamma connection in the quasar 3C 279. A comparison of the flux variability in jet features with the gamma-ray variability suggests that the gamma-ray variability is correlated with a particular region downstream from the observed base of the jet at a distance of about 140 lt-yr. This feature shows an apparent superluminal velocity of about 3.7 times the speed of light, implying that one of the gamma-ray emission zones is not stationary. Further details can be found in the original publication at the Astronomy & Astrophysics journal here.
Event Horizon Telescope Collaboration Announces New Management Team
17 September 2019
Professor Anton Zensus, the Chairman of the Board of the Event Horizon Telescope Collaboration, announces the search for a new EHT director and changes to the EHT management, which become effective on September 17, 2019.
The US National Science Foundation has announced the funding of a $12.7M Mid-Scale research innovation grant (MSRI), to develop technologies and techniques that will help to create transformational capabilities for a next-generation Event Horizon Telescope array, envisaged for the second half of the 2020s. Shep Doeleman is PI of this award, and several other US institutions are participating.
“The development of long-term technologies and techniques is an important step towards taking the Event Horizon Telescope into the future. There are none more qualified to lead such a visionary effort than Shep, and we are looking forward to working with him over the coming months to help coordinate the MSRI activities with related work across the EHT collaboration” notes Anton Zensus.
The EHT Board recognizes Shep Doeleman as the Founding Director of the Event Horizon Telescope, acknowledging his leadership to the phenomenal success of the EHT, which led to the first image of a black hole in the galaxy Messier 87.
"The spectacular M87 EHT results have surpassed our wildest expectations, and I am deeply proud of what we achieved as a team. Now the question one hears the most is "what's next?", and the next-generation EHT initiative is the exciting clear response. I look forward to continuing to support the EHT, and am delighted to focus on this new direction." says Shep Doeleman, EHT Founding Director.
The Board will immediately initiate the search to fill the now vacant position of EHT Director, while supporting continuity of the activities of the project through a series of management changes.
* Mike Hecht, Associate Director at Haystack Observatory, will serve as Deputy Project Director;
* Geoff Bower of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), the vice Chair of the EHT Science Council, will serve as Project Scientist.
* Remo Tilanus of Leiden Observatory will serve as Operations Manager.
* David James of the Harvard-Smithsonian Center for Astrophysics will continue to provide project management support to the Team.
“The EHT Management Team is enhanced to address the evolving management and communication needs of our collaboration, which has seen rapid growth in membership, and increasing complexity in operations, scientific and development activities. Shep has graciously offered to continue to advise the Management Team during the transition period” adds Zensus.
Further information:
|
Prof. Dr. J. Anton Zensus |
Dr. Colin J. Lonsdale |
Prof. Dr. Eduardo Ros |
|
EHT Board Chairman |
EHT Board Vice-Chairman |
EHT Board Executive Secretary |
|
MPI für Radioastronomie, Bonn, Germany |
MIT Haystack Observatory, Westford, MA, USA |
MPI für Radioastronomie, Bonn, Germany |
|
Tel. +49 228 525 378 |
Tel. +1 617 715 5575 |
Tel. +49 228 525 125 |
A Test of General Relativity at The Galactic Center
25 July 2019
In a detailed study of a star orbiting the supermassive black hole at the center of our Galaxy, researchers report that Einstein’s theory of general relativity (GR) accurately describes motion around this massive structure. Tuan Do, Andrea Ghez and their colleagues including Gunther Witzel from the Max Planck Institute for Radio Astronomy in Bonn, Germany, report novel spectral data and expanded analyses. The findings are presented in this week’s issue of the magazine „Science“ (UCLA Press Release, 25 July 2019). [more]
Gamma-ray emission in radio galaxies under the VLBI scope
15 July 2019
The POLAMI Collaboration has published a study, led by the MPI für Radioastronomie researcher R. Angioni, of the gamma-ray emission of Southern radio galaxies. These results are published in the last issue of the Astronomy & Astronomy journal. The study shows that the brightness of the core of the radio sources correlates with the gamma-ray emission, as seen in blazars. However, the gamma-ray luminosity does not show dependence with the compact radio emission of the core of the galaxies, which is a common indicator of Doppler boosting. The authors conclude that the gamma-ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, according with the unified model of jetted active galactic nuclei. More information is available here.
The large gamma-ray flare of the flat-spectrum radio quasar PKS 0346−27
12 July 2019
A multi-messenger study led by R. Angioni of the MPI für Radioastronomie, published in the present issue of Astronomy & Astrophysics, reports on the long- and short-term flux and spectral variability from the radio quasar PKS 0346−27, producing gamma-ray light curves with different time binning. Evidence of short-time scale variability down to 90 min is presented. The source shows remarkable properties during an outburst in May 2018, and is a promising target for future ground-based Cherenkov observatories. More information is available at the original publication here.
The gamma-loud radio galaxy 3C 264
4 July 2019
A team of astronomers led by the astronomer B. Boccardi of the MPI für Radioastronomie publishes in the latest issue of Astronomy & Astrophysics a high-resolution radio study of the gamma-ray emitting galaxy 3C 84. The authors present a adio and X-ray analysis of the jet in 3C 264. They determine the main physical parameters of the parsec-scale flow and explore the implications of the inferred kinematic structure for radiative models of this γ-ray emitting jet. The publication suggests that the high-energy emitting region is located at the end of the acceleration zone of the jet, either in the jet layer or in the spine. Further information can be found here.
A study of the physics of the complex jet in the blazar S5 0836+710
3 July 2019
The last issue of the journal Astronomy & Astrophysics reports the results of a thorough analysis of the jet profile of the high-resolution images of the blazar S5 0836+710. The study is led by the MPI für Radioastronomie researcher L. Vega García. The authors ran numerical calculations of stability of a relativistic, sheared jet over a range of different jet parameters, based on the assumption that the observed structures are generated by growing Kelvin–Helmholtz instability modes. The results yield physical parameters of the jet, with a Lorentz factor of 12 and an internal Mach number of 12, as well as a jet-to-ambient medium density of 1/1000. More details can be found in the original publication here.