Highlights — Some exciting recent scientific results from our group

Astronomers reveal first image of the black hole at the heart of the Milky Way
Breakthrough discovery: EHT´s unprecedented observations improve our understanding of what happens at the very centre of our galaxy

Astronomers have unveiled the first image of the supermassive black hole at the centre of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the nature of such giants, which are thought to reside at the centers of most galaxies. The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes.  The Max Planck Institute for Radio Astronomy (MPIfR) in Bonn plays a major role in all the aspects of this discovery, from founding and establishing the EHT collaboration to the final production and interpretation of the data. more
The Hunt for the Gravitational Wave Background
NASA’s FERMI Satellite Hunts for Extremely Long-wavelength Gravitational Wave Signals

Coalescing supermassive black holes in the centers of merging galaxies fill the universe with low-frequency gravitational waves.  Astronomers have been searching for these waves by using large radio telescopes to look for the subtle effect these spacetime ripples have on radio waves emitted by pulsars within our Galaxy.  Now, an international team of scientists has shown that the high-energy light collected by NASA’s Fermi Gamma-ray Space Telescope can also be used in the search.  Using gamma rays instead of radio waves yields a clearer view to the pulsars and provides an independent and complementary way to detect gravitational waves. more
Cosmic flashes pinpointed to a surprising location in space
Localisation of a recurring source of radio flashes in the nearby galaxy M81

Astronomers have been surprised by the closest source of mysterious flashes in the sky called fast radio bursts. Precision measurements with radio telescopes reveal that the bursts are made among old stars, and in a way that no one was expecting. The source of the flashes, in nearby spiral galaxy M 81, is the closest of its kind to Earth. more
The Search for an Isotropic Gravitational Wave Background
World-wide radio telescope network enhances signal that may hint at ultra-low frequency gravitational waves

An international team of astronomers including a number of scientists from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has announced the results of a comprehensive search for a background of ultra-low frequency gravitational waves. These light-year-scale ripples, a consequence of general relativity, permeate all of spacetime and could originate from mergers of the most massive black holes in the Universe or from events occurring soon after the formation of the Universe in the Big Bang. more
Einstein wins again

Einstein wins again

December 13, 2021
The theory of general relativity passes a range of precise tests set by pair of extreme stars

An international team of researchers from ten countries led by Michael Kramer from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has conducted a 16-year long experiment to challenge Einstein’s theory of general relativity with some of the most rigorous tests yet. Their study of a unique pair of extreme stars, so called pulsars, involved seven radio telescopes across the globe and revealed new relativistic effects that were expected and have now been observed for the first time. Einstein’s theory, which was conceived when neither these types of extreme stars nor the techniques used to study them could be imagined, agrees with the observation at a level of at least 99.99%. more
Jet from giant galaxy M87: Computer modelling explains black hole observations
November 22, 2021
An enormous jet of particles emitted by the giant galaxy M87 can be observed astronomically in various wavelengths. Dr. Alejandro Cruz Osorio and Professor Luciano Rezzolla from Goethe University Frankfurt together with an international team of scientists including Professor Michael Kramer (MPIfR bonn) within the framework of the BlackHoleCam research project has succeeded in developing a theoretical model of the morphology of this jet using complex supercomputer calculations. The images from these calculations provide an unprecedented match with astronomical observations and confirm Einstein’s theory of general relativity (Press Release, Frankfurt University, November 04, 2021). more
Towards the Detection of the Nanohertz Gravitational-wave background
The European Pulsar Timing Array provides a significant step forward

The European Pulsar Timing Array collaboration reports on the outcome of a 24 year observing campaign with five large-aperture radio telescopes in Europe, resulting in a candidate signal for the since-long sought gravitational wave background due to in-spiraling supermassive black-hole binaries. The collaboration brings together teams of astronomers around the largest European radio telescopes including the 100-m Effelsberg radio telescope of the Max Planck Institute for Radio Astronomy in Bonn, Germany, as well as groups specialized in data analysis and modelling of gravitational wave signals. Although a detection cannot be claimed yet, this represents a significant step in the effort to finally unveil gravitational waves at very low frequencies in the Nanohertz regime. The candidate signal has emerged from an unprecedented detailed analysis using two independent methodologies and shares strong similarities with results found from the analyses of other teams. more
Over A Thousand Cosmic Explosions in FRB 121102 Detected by FAST
October 13, 2021
An international research team led by Di Li and Pei Wang (National Astronomical Observatories of the Chinese Academy of Sciences) including Marylin Cruces, Michael Kramer and Laura Spitler from the MPIfR in Bonn caught an extreme episode of cosmic explosions from the Fast Radio Burst FRB 121102, using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). A total of 1,652 independent bursts were detected within 47 days (Nature Paper & NAOC Press release, October 13, 2021). more
GLOSTAR - tracing atomic and molecular gas in the Milky Way
Two powerful telescopes provide the most detailed radio maps of the Northern Galactic Plane

By combining two of the most powerful radio telescopes on Earth, an international team of researchers led by the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, created the most sensitive maps of the radio emission of large parts of the Northern Galactic plane so far. The data were taken with the Karl G. Jansky Very Large Array (VLA) in New Mexico in two different configurations and the 100-m Effelsberg telescope near Bonn. This provides for the first time a radio survey covering all angular scales down to 1.5 arc-seconds, the apparent size of a tennis ball lying on the ground and seen from a flying plane. Contrary to previous surveys, GLOSTAR observed not only the radio continuum in the frequency range from 4-8 GHz in full polarization, but simultaneously also spectral lines that trace the molecular gas (from methanol and formaldehyde) and atomic gas via radio recombination lines. more
FAST Radio Telescope Detects 3D Spin-velocity Alignment in a Pulsar
Based on observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, an international research team led by Jumei Yao, including Michael Kramer from the MPIfR, found the first evidence for three-dimensional (3D) spin-velocity alignment in pulsars.The study was published in Nature Astronomy on May 6 (CAS-Press Release, May 07, 2021).
A new telescope to study Einstein’s theory and Nature’s most compact objects
Using the South African MeerKAT telescope, astronomers started to systematically explore binary pulsars for tests of gravity

An international group of astronomers, led by the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany and the University of British Columbia (UBC) in Vancouver presents the first results of a large program to use South Africa’s MeerKAT radio telescope to test the theories of Einstein with unprecedented precision.
The Discovery of 8 New Millisecond Pulsars
South Africa’s MeerKAT Radio Telescope explored the central regions of globular clusters in search of very weak pulsars

A group of astronomers, led by the Italian National Institute of Astrophysics (INAF) and the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany, has discovered 8 millisecond pulsars located within dense clusters of stars, known as “globular clusters”, using South Africa’s MeerKAT radio telescope. Millisecond pulsars are neutron stars, the most compact star known, that spin up to 700 times per second. This result comes from the synergic work of two international collaborations, TRAPUM and MeerTIME.
Famous fast radio burst FRB20180916B just barely lets itself be captured
Two international teams of astronomers have narrowed-down the origin of the flashes produced in the fast radio burst FRB20180916B by examining them with the highest time resolution and at the lowest possible frequencies. These studies, using the Effelsberg 100-m telescope within the EVN network and the European LOFAR telescope network, have been published in Nature Astronomy and in The Astrophysical Journal Letters (JIVE Press Release, April 15, 2021).
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