Highlights — Some exciting recent scientific results from our group

Lightest black hole or heaviest neutron star?
MeerKAT uncovers a mysterious object at the boundary between black holes and neutron stars

An international team of astronomers, led by researchers from the Max Planck Institute for Radio Astronomy, have used the MeerKAT radio telescope to discover an intriguing object of an unknown nature in the globular cluster NGC 1851. The massive object is heavier than the heaviest neutron stars known and yet simultaneously lighter than the lightest black holes known and is in orbit around a rapidly spinning millisecond pulsar. This could be the first discovery of the much-coveted radio pulsar - black hole binary; a stellar pairing that would allow new tests of Einstein’s general relativity. more
Extreme stars share unique properties that may provide a link to mysterious sources
A universal relation for pulsars, magnetars and potentially fast radio bursts

An international research team led by Michael Kramer and Kuo Liu from the Max Planck Institute for Radio Astronomy in Bonn, Germany, have studied a rare species of ultra-dense stars, so called magnetars, to uncover an underlying law that appears to apply universally to a range of objects known as neutron stars. This law gives insight into how these sources produce radio emission and it may provide a link to the mysterious flashes of radio light, Fast Radio Bursts, that originate from the distant cosmos. more
New radio astronomical observations confirm unintended electromagnetic radiation emanating from large satellite constellations
Scientists use the LOFAR telescope to observe low-frequency radio waves from satellites in large constellations for the first time


Scientists from a number of leading research institutions including the Max Planck Institute for Radio Astronomy in Bonn, Germany, used the Low Frequency Array (LOFAR) telescope to observe 68 of SpaceX’s satellites. The authors conclude that they detected "unintended electromagnetic radiation" emanating from onboard electronics. This is different from communications transmissions, which had been the primary focus for radio astronomers so far.  The unintended radiation could impact astronomical research. They encourage satellite operators and regulators to consider this impact on radio astronomy in spacecraft development and regulatory processes alike. more
A new view of the Universe
Clock-like precision of pulsars opens a new window in the gravitational wave spectrum

An international collaboration of European astronomers including scientists from the Max Planck Institutes for Radio Astronomy  and Gravitational Physics, together with Indian and Japanese colleagues, have published the results of more than 25 years of observations from six of the World's most sensitive radio telescopes. Along with other international collaborations, the European and Indian Pulsar Timing Arrays have independently found evidence for ultra-low-frequency gravitational waves, expected to come from pairs of supermassive black holes found in the centres of merging galaxies. These results are a crucial milestone in opening a new, astrophysically rich window in the gravitational wave spectrum. more
Gamma-ray eclipses shed new light on spider pulsars
January 26, 2023
Seven rare eclipsing binaries identified and five neutron stars weighed

Mankind has watched the cosmic ballet of eclipses for millennia. Solar and lunar eclipses, those of Jupiter’s moons, and stellar occultations by planets and asteroids have also provided new physical measurements and insights about our Universe. Using NASA’s Fermi Gamma-ray Space Telescope, astronomers have now identified seven rare stellar binary systems in which a neutron star is eclipsed by its stellar companion. This allowed the international research team led by scientists from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Hannover and including researchers from MPIfR Bonn to weigh those neutron stars. Precisely measuring neutron star masses improves our understanding of matter in extreme conditions and has implications for fundamental physics. In the future, these seven binary systems could also provide new opportunities to observe Einstein’s theory of general relativity in action. more
Nine new and exotic creatures for the pulsar zoo
New discoveries from the Transients and Pulsars with MeerKAT Project

Nine millisecond pulsars, most of them in rare and sometimes unusual binary systems: that is the first result of a targeted survey with the South African MeerKAT telescope array. An international team of astronomers with significant contributions from researchers at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) and the Max Planck Institute for Radio Astronomy (MPIfR) selected 79 unidentified pulsar-like sources from observations of NASA’s Fermi Gamma-ray Space Telescope and observed them at radio frequencies with MeerKAT. Using this tried-and-tested method with a next-generation telescope array has significant advantages over previous surveys. The team discovered nine rapidly rotating neutron stars, most of them with unusual properties.

They performed multi-wavelength follow-ups, finding gamma-ray pulsations from two of these objects, optical counterparts, as well as X-rays from another one of the systems. AEI scientists also searched for continuous gravitational waves from one of the neutron stars. These results emphasize the value of targeted searches for radio pulsars in unidentified gamma-ray sources and hold promise for the future: the researchers are certain that several more millisecond pulsars can be discovered by future observations. more
RAS Group Award 2023 goes to MeerKAT
The MeerKAT radio telescope in South Africa receives prestigious award of the Royal Astronomical Society

The MeerKAT team is awarded the Group Award of the Royal Astronomical Society for a series of spectacular observations in radio astronomy, the highlight being the images of the Galactic Centre region and the spectacular radio bubbles. In addition, the MeerKAT team have supported the development of science and technology in Africa and stress-tested technology for the Square Kilometre Array.

The Max Planck Institute for Radio Astronomy (MPIfR) and the Max-Planck-Gesellschaft in Germany, are involved in the MeerKAT project by providing a set of receivers in the S-Band frequency range for each of the dishes and also by an extension project increasing the total number of MeerKAT dishes from 64 to 84, thus increasing sensitivity, spatial resolution and image quality of the telescope.

Coincidentally, a new science result based on MeerKAT observations led by MPIfR scientists is published on the same day which has solved a 20-year old mystery: pulsar observations of the globular cluster M30 led to the re-detection of a long-time missing millisecond pulsar in a highly eccentric binary orbit. The findings are published today in The Astrophysical Journal Letters (ApJL). more
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