Contact

Prof. Dr. J. Anton Zensus

Director and Head of the Research Department
"Radio Astronomy/VLBI"

Phone: +49 228 525-298 (Secretary)

https://antonzensus.mpifr-bonn.mpg.de

Radio Astronomy / VLBI

Radio Astronomy / VLBI

 
<p>March 05, 2015<br /><br />A black hole discovered wandering all by itself inside one of the spiral arms of the galaxy NGC 2276 may present an important clue that would fill the gap in the evolutionary story of black holes. This discovery has been reported recently by a research team which is led by Mar Mezcua from the Harvard Centre for Astrophysics in Boston and includes Andrei Lobanov from the Max-Planck-Institut f&uuml;r Radioastronomie (MPIfR) in Bonn. They identify this elusive black hole, called NGC 2276-3c. The astronomers had to look at it simultaneously at radio waves with the European Very Long Baseline Interferometry Network, or EVN, and in X-rays with NASA&rsquo;s Chandra Space Observatory. The combination of X-ray and radio data enables the researchers to &lsquo;weigh&rsquo; the black hole, which has turned out to be as heavy as about 50,000 Suns. With this mass, it fills a gap between stellar black holes found in our own Galaxy and supermassive black holes residing in centers of most of the massive galaxies. Such intermediate-mass black holes are probably the seeds from which supermassive black holes will form.</p>

A missing link in the family tree of cosmic black holes

March 05, 2015

A black hole discovered wandering all by itself inside one of the spiral arms of the galaxy NGC 2276 may present an important clue that would fill the gap in the evolutionary story of black holes. This discovery has been reported recently by a research team which is led by Mar Mezcua from the Harvard Centre for Astrophysics in Boston and includes Andrei Lobanov from the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn. They identify this elusive black hole, called NGC 2276-3c. The astronomers had to look at it simultaneously at radio waves with the European Very Long Baseline Interferometry Network, or EVN, and in X-rays with NASA’s Chandra Space Observatory. The combination of X-ray and radio data enables the researchers to ‘weigh’ the black hole, which has turned out to be as heavy as about 50,000 Suns. With this mass, it fills a gap between stellar black holes found in our own Galaxy and supermassive black holes residing in centers of most of the massive galaxies. Such intermediate-mass black holes are probably the seeds from which supermassive black holes will form.

[more]

Gamma-loud narrow-line Seyfert 1 galaxies studied in the radio

February 23, 2015

A international team led by Dr. Emmanouil Angelakis from the MPI for Radio Astronomy in Bonn has studied the radio jet emission from a puzzling class of active galactic nuclei: the narrow-line Seyfert 1 galaxies emitting gamma rays at the GeV range of energies.  They studied four objects which were detected by the space gamma-ray satellite Fermi and in the radio, discovered in the early 2010s.   As of today, seven of these objects have been discovered.  The four studied sources show the typical characteristics of blazars such as intensive variability, spectral evolution corresponding to traveling plasma shocks, and Doppler factors indicating mildly relativistic speeds in the jet. This work has been published in the last issue of the international journal Astronomy & Astrophysics. [more]

Radiation from the heart of the powerful quasar RX J2314.9+2243

February 4, 2015

An international team lead by S. Komossa from the MPI for Radio Astronomy, has observed the quasar RX J2314.9+2243 in the optical, ultra-violet, X-rays, and radio bands.  A fifth of all active galaxies is radio loud.  A new class of these objects was discovered in the last years, the narrow-line Seyfert 1 galaxies.  Those objects have extreme emission properties.  One of them, with a high radio loudness, has been observed systematically by the Bonn team.  The results show an energy distribution originated by electrons under the influence of strong magnetic fields (synchrotron radioation).  This quasar shows as well a powerful outflow in the optical part of the spectrum.  The results of this work have been published in the latest issue of Astronomy & Astrophysics. [more]

How compact and bright can be a source in the sky?

January 30, 2015

The answer of this question can be better answered after the last development published in the last issue of Astronomy & Astrophysics by Andrei P. Lobanov from the MPI for Radio Astronomy.  The physical properties of compact sources can be characterised by the brightness temperature.  The new method presented by Lobanov, which allows us to compute the brightness temperature limits from interferometric measurements, has been successfully tested with data from the MOJAVE project and from mm-VLBI observations.  Its appliacation to space VLBI obsrvations promises new limits in the brightness temperature of compact, remote objects, for future observations. [more]

A new method to analyse astronomical images

January 27, 2015

A new, automatic method for astronomical image analysis has been developed by the graduate student Florent Mertens and his supervisor, Andrei Lobanov, both at the MPI for Radio Astronomy.  This mehtod is based on wavelet functions to determine distinct regions in astronomical images and to study their evolution, following the wavelet-based image segmentation and evaluation (WISE) approach.  This was successfully tested in the sources 3C 273 and 3C 120.  The two-dimensional evolution of the features of the jets in both sources was studied, and it is compatible with the effect of Kelvin-Helmholtz instabilities.  This work was published in the last issue of the journal Astronomy & Astrophysics [more]

 
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