LISA Pathfinder – A Space Saga Part 6 – May 04, 2021

Artist’s impression of LISA Pathfinder operating in space © ESA/ATG medialab

It is May 4th 2021. The LPF mission has ended and the LISA mission is even now in the first phase of realization. LISA will be the largest space structure ever, but LISA is no Death Star. LISA’s mission: to probe the Dark Side of the Universe.
Happy Star Wars Day!

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EHT Astronomers Image Magnetic Fields at the Edge of M 87’s Black Hole – March 24, 2021

Polarisation in the very centre of galaxy M87. Polarization “field lines” are plotted atop an underlying total intensity image (the “shadow of a black hole” image from April 2019). The sweeping lines in the image indicate streamlines of the magnetic field. To emphasize the regions with stronger polarisation detections, length and opacity of the streamlines are scaled with the polarised intensity. © EHT-Kollaboration

Event Horizon Telescope Observations of Polarised Radio Emission of the Supermassive Object in the Centre of M87

The Event Horizon Telescope (EHT) team, including astronomers at the Max-Planck-Institut für Radioastronomie, has revealed today new observations that are key to explaining how the M 87 galaxy is able to launch an energetic jet from its core. The new view of the massive object at the centre of the M 87 galaxy shows how it looks in polarised light. For the first time, astronomers have been able to measure the polarisation, a signature of magnetic fields, this close to the edge of a black hole. They publish a key snapshot in order to understand how a jet larger than the galaxy is launched.

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New LIGO Magazine Issue 18 is out – March 19, 2021

Find out more about art, music & gravitational waves as well as results from observing run 3a and more.

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A brighter future for gravitational-wave astronomy – March 17, 2021

Fiber lasers are – due to their special beam properties – expected to be used in future gravitational-wave detectors, which will listen ten times more sensitively for gravitational waves. © LZH

Hannover research team develops most powerful laser system yet for gravitational-wave detectors

Future gravitational-wave detectors on Earth will use laser light with even higher power than in current instruments. Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), the Laser Zentrum Hannover e.V. (LZH), and Leibniz University Hannover have now developed a new laser system for this purpose. They combined the custom tailored light from two high-power lasers so precisely that it meets the requirements for use in gravitational-wave detectors. In a next step, the researchers will improve their system at AEI so that it can be used as a centerpiece for next-generation detectors. The results have now been published in the journal Optics Express.

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Five years ago LISA Pathfinder started its scientific work – Follow the saga … – February 18, 2021

LISA Pathfinder being encapsulated within the Vega rocket. © ESA–Manuel Pedoussaut

Relive the groundbreaking technology demonstrator’s mission milestones in a new Youtube mini-series released by the LISA Consortium.

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GEO600 reaches 6 dB of squeezing – January 27, 2021

GEO600 background noise measurements. The horizontal axis shows the frequency, the vertical axis the strength of the detector noise at these frequencies. The lower the curves are, the less noise is present and the better gravitational waves can be measured. The blue curve shows the noise without the squeezed light source, the red curve shows the noise with the squeezed light source. The improvements occur mainly at high frequencies. © Max Planck Institute for Gravitational Physics

German-British instrument mitigates quantum noise effects better than any gravitational-wave detector before

Gravitational waves cause tiny length changes in the kilometer-size detectors of the international network (GEO600, KAGRA, LIGO, Virgo). The instruments use laser light to detect these effects and are so sensitive that they are fundamentally limited by quantum mechanics. This limit manifests as an ever-present background noise which can never be fully removed and which overlaps with gravitational-wave signals. But one can change the noise properties – using a process called squeezing – such that it does not disturb the measurements as much. Now, GEO600 researchers have achieved the strongest squeezing ever seen in a gravitational-wave detector. They lowered the quantum mechanical noise by up to a factor of two. This is a big step to third-generation detectors such as the Einstein Telescope and Cosmic Explorer. The GEO600 team is confident to reach even better squeezing in the future.

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German Research Foundation supports new collaborative research center TerraQ – December 02, 2020

Logo of the SFB “TerraQ”

The Institute for Gravitational Physics at Leibniz University Hannover will do research on and improve interferometric precision measurements and laser links between satellites

The collaborative research center (Sonderforschungsbereich / SFB) “Relativistic and Quantum-Based Geodesy (TerraQ)”, funded by the German Research Foundation (Deutsche Forschungsgemeinschaft / DFG), investigates novel methods of geodesy using fundamentally new sensors, measurement techniques, analysis methods and modeling approaches. Researchers of the Institute for Gravitational Physics at Leibniz Universität Hannover contribute their decades of experience and their worldwide leading role in the field of interferometric precision measurements and laser links between satellites. Basic research is thereby used in climate research and improves the precious data at its foundation.

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Dozens of new gravitational-wave events in six months – October 29, 2020

The mergers of compact objects discovered so far by LIGO and Virgo (in O1, O2 and O3a). The diagram shows black holes (blue), neutron stars (orange) and compact objects of unknown nature (grey), which were detected by their gravitational-wave emission. Each merger of a binary system corresponds to three compact objects shown: the two merging objects and the result of the merger. A selection of black holes (violet) and neutron stars (yellow) discovered by electromagnetic observations is shown for comparison. © LIGO Virgo Collaboration / Frank Elavsky, Aaron Geller / Northwestern

New LIGO/Virgo catalog contains 50 gravitational-wave signals, several from unusual sources

The LIGO Scientific Collaboration and the Virgo Collaboration have published updates to their catalog of gravitational-wave signals, their astrophysical implications and more stringent tests of general relativity. The Gravitational-Wave Transient Catalog 2 (GWTC-2) now contains 50 signals compared to 11 signals in the previous version. The 39 new discoveries were found in O3a, the first six months of the third joint observing run “O3”, which began on 1 April 2019. The new signals come from different astrophysical systems of merging black holes and neutron stars in all possible combinations. Some exceptional events have already been published in the previous months. While the new catalog contains many binary black hole mergers found routinely, it also features some more surprises, such as the most light-weight merger of two black holes or a possible merger of a black hole and a neutron star. Results from the second half of O3 will be published later and should contain more surprises from the Dark Universe.

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Super heavyweight and flyweight in a cosmic dance – October 22, 2020

The entire sky as seen by the Fermi Gamma-ray Space Telescope and the new pulsar discovered by Einstein@Home. The field below the magnified inset shows the pulsar name and some of its measured characteristics, as well as its gamma-ray pulsations. The flags show the nationalities of the volunteers whose computers found the pulsar. © Knispel/Max Planck Institute for Gravitational Physics/NASA/DOE/Fermi LAT Collaboration

Volunteer distributed computing project Einstein@Home discovers neutron star in unusual binary system
After more than two decades, an international research team led by the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover has identified a Galactic “mystery source” of gamma rays: a heavy neutron star with a very low mass companion orbiting it. Using novel data analysis methods running on about 10,000 graphics cards in the distributed computing project Einstein@Home, the team identified the neutron star by its regularly pulsating gamma rays in a deep search of data from NASA’s Fermi satellite. Surprisingly, the neutron star is completely invisible in radio waves. The binary system was characterized with an observing campaign across the electromagnetic spectrum, and breaks several records.

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The ring around the M 87* black hole shadow glitters – September 23, 2020

Snapshots of the M 87* black hole obtained through imaging / geometric modeling, and the EHT array of telescopes in 2009-2017. The diameter of all rings is similar, but the location of the bright side varies. The variation of the thickness of the ring is most likely not real and results from the limited number of participating VLBI stations in earlier experiments. © M. Wielgus, D. Pesce & the EHT Collaboration

Turbulent evolution of the M 87* black hole image from 2009 to 2017

In 2019, the Event Horizon Telescope (EHT) Collaboration delivered the first image of a black hole, revealing M 87*—the supermassive object in the center of the Messier 87 galaxy. The EHT team, a collaboration with strong engagement of the MPI für Radioastronomie, has now used the lessons learned last year to analyze the archival data sets from 2009-2013, some of them not published before. The contribution of the APEX telescope is very important for the success of this analysis.

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Squeezed light makes Virgo’s mirrors jitter – September 22, 2020

Together with their Virgo colleagues, the AEI researchers Harald Lück, Moritz Mehmet, and Henning Vahlbruch install the squeezed-light source, which was developed in Hannover, in a cleanroom at the Virgo gravitational-wave detector. © H. Lück/B. Knispel/Max Planck Institute for Gravitational Physics

A quantum mechanical effect demonstrated for the first time in the Advanced Virgo gravitational-wave detector
Quantum mechanics does not only describe how the world works on its smallest scales, but also affects the motion of macroscopic objects. An international research team, including four scientists from the MPI for Gravitational Physics (Albert-Einstein-Institut/AEI) and Leibniz University in Hannover, Germany, has shown how they can influence the motion of mirrors, each weighing more than 40 kg, in the Advanced Virgo gravitational-wave detector trough the deliberate use of quantum mechanics. At the core of their experiment published today in Physcial Review Letters is a squeezed-light source, developed and built at the AEI in Hanover, which generates specially tuned laser radiation and improves the detector’s measurement sensitivity during observing runs.

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Einstein Telescope proposal submitted to ESFRI roadmap – September 10, 2020

Artist’s impression of the underground Einstein Telescope. © NIKHEF

The proposal to include the Einstein Telescope, a pioneering third-generation gravitational-wave (GW) observatory, in the 2021 update of the European Strategic Forum for Research Infrastructures (ESFRI) roadmap has been submitted. The ESFRI roadmap describes the future major research infrastructures in Europe. The Einstein Telescope (ET) is the most ambitious project for a future terrestrial observatory for GWs.

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LIGO and Virgo catch their biggest fish so far – September 02, 2020

Numerical simulation of two black holes that inspiral and merge, emitting gravitational waves. The black holes have large and nearly equal masses, with one only 3% more massive than the other. The simulated gravitational wave signal is consistent with the observation made by the LIGO and Virgo gravitational wave detectors on May 21st, 2019 (GW190521). © N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration

Far-away black hole collision is the most massive and most distant ever observed by the gravitational-wave detectors

The fourth gravitational-wave detection from LIGO’s and Virgo’s third observing run published today is very big news: the most massive merger of two black holes ever observed to date. The black-hole collision formed a 142 solar-mass black hole when the Universe was half its current age. This is the first direct observation of the birth of an intermediate-mass black hole. Even more surprising is the heavier black hole in the pair: with 85 times the mass of our Sun, it should not exist according to the current understanding of stellar explosions, but it could be born from an earlier binary merger. It is unknown whether this signal, GW190521, is the first observed representative of a new class of binary black holes or is simply at the upper end of a wide mass spectrum. Scientists at the Max Planck Institute for Gravitational Physics in Potsdam and Hannover and at the Leibniz University Hannover have made crucial contributions to the discovery and its interpretation.

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Collaboration between gravitational-wave astronomy and particle physics established – September 01, 2020

Black hole scattering can be treated as a particle-like interaction, in which the black holes exchange gravitons. By calculating the quantum scattering amplitudes, researchers can obtain important information about merging black hole binaries that emit gravitational waves. © APS/Alan Stonebraker

The departments of Professor Alessandra Buonanno (Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI)) and Professor Zvi Bern (Mani L. Bhaumik Institute for Theoretical Physics (University of California in Los Angeles, UCLA)) will cooperate on developing waveform models for future gravitational-wave detectors. Senior researcher Dr. Justin Vines will perform the balancing act between particle physics at UCLA and gravitational wave modeling at the AEI. For the next two years, he will be based at AEI, then he will move over to UCLA. Long-term visits between both institutions are planned in order to maintain collaborations with researchers in Potsdam and Los Angeles. The goal is to foster the use of advanced computational techniques originating from quantum field theory to develop ever more accurate gravitational waveform models, enabling further discoveries with gravitational-wave detectors as they become more and more sensitive.

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Artist’s impression of a LISA spacecraft. © AEI/MM/exozet

The Laser Interferometer Space Antenna (LISA) will be the first gravitational wave observatory in space, to be launched 2034. It is one of the European Space Agency’s (ESA’s) three large missions with contributions from NASA.

The LISA Symposium will take place online from September 1 to 3.

Besides live presentations on YouTube (or Zoom, then with discussion and commentary opportunities for registered participants) there will be recorded presentations, which are already available. More information:

Homepage and registration: 

Agenda and talks:

LISA Consortium:

Twitter: #LISAXIII

Registration is free. Please get in touch with if you have any questions or if you are looking for experts to talk to on various topics.

Susanne Milde
Milde Marketing Science Communication
+49 172 393 1349

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A black hole with a puzzling companion – June 23, 2020

Visualization of the coalescence of two black holes that inspiral and merge, emitting gravitational waves. One black hole is 9.2 times more massive than the other and both objects are non-spinning. © N. Fischer, S. Ossokine, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration

LIGO and Virgo find another surprising binary system

The harvest of exceptional gravitational-wave events from LIGO’s and Virgo’s third observing run (O3) grows. A new signal published today comes from the merger of a 23-solar-mass black hole with an object 9 times lighter. The second object is mysterious: its measured mass puts it in the so-called “mass gap” between the heaviest known neutron stars and the lightest known black holes. While the researchers cannot be sure about its true nature, one thing is clear: the observation of this unusual pair challenges the current understanding of how such systems are born and evolve.

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New movie about LISA, the first gravitational wave observatory in space – June 03, 2020

© Max Planck Institute for Gravitational Physics (Albert Einstein Institute) / Milde Marketing Science Communication / Exozet Effects

On the occasion of the 236th meeting of the American Astronomical Society the LISA Consortium launched a new movie about ESA´s LISA mission. LISA is a space mission led by ESA with contributions from NASA and many ESA member states. LISA will observe gravitational waves in space with three satellites connected by laser beams forming a constellation in a heliocentric orbit.

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A signal like none before – April 20, 2020

Binary black hole merger where the two black holes have distinctly different masses of about 8 and 30 times that of our Sun. © N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes project

LIGO and Virgo detectors catch first gravitational wave from binary black hole merger with unequal masses

The expectations of the gravitational-wave research community have been fulfilled: gravitational-wave discoveries are now part of their daily work as they have identified in the past observing run, O3, new gravitational-wave candidates about once a week. But now, the researchers have published a remarkable signal unlike any of those seen before: GW190412 is the first observation of a binary black hole merger where the two black holes have distinctly different masses of about 8 and 30 times that of our Sun. This not only has allowed more precise measurements of the system’s astrophysical properties, but it has also enabled the LIGO/Virgo scientists to verify a so far untested prediction of Einstein’s theory of general relativity.

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25 years: Happy birthday AEI – April 02, 2020

Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam © Albert Einstein Institute

Visit founding director Prof Bernard F Schutz´ blog for the story:

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The new LIGO Magazine Issue 16 is out! – March 18, 2020

LIGO Magazin Issue 16 3/2020

Find out more about the O3 commissioning break, GW190425 and more here:

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Continued Discoveries from Public Data – March 12, 2020

Numerical-relativity simulation of the first binary black-hole merger observed by the Advanced LIGO detector on September 14, 2015. Credit: S. Ossokine, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes project, W. Benger (Airborne Hydro Mapping GmbH)

International team led by Max Planck researchers finds promising new candidates for gravitational waves from binary black hole mergers in public LIGO/Virgo data

Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover together with international colleagues have published their second Open Gravitational-wave Catalog (2-OGC). They used improved search methods to dig deeper into publicly available data from LIGO’s and Virgo’s first and second observation runs. Apart from confirming the ten known binary black hole mergers and one binary neutron star merger, they also identify four promising black hole merger candidates, which were missed by initial LIGO/Virgo analyses. These results demonstrate the value of searches in public LIGO/Virgo data by research groups independent of the LIGO/Virgo collaborations. The research team also makes available its complete catalogue in addition to detailed analysis of more than a dozen possible binary black hole mergers.

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How big is a neutron star? – March 09, 2020

A neutron star is the densest object astronomers can observe directly, crushing half a million times Earth’s mass into a sphere about 22 kilometers across, according to the new results. This illustration compares the size of a neutron star to the area around Hannover, Germany, hometown of the Albert Einstein Institute Hannover. © NASA’s Goddard Space Flight Center

International team uses a novel approach combining gravitational-wave observations, multi-messenger astronomy, and nuclear physics to obtain the best measurement of neutron star size to date.

An international research team led by members of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) has obtained new measurements of how big neutron stars are. To do so, they combined a general first-principles description of the unknown behavior of neutron star matter with multi-messenger observations of the binary neutron star merger GW170817. Their results, which appeared in Nature Astronomy today, are more stringent by a factor of two than previous limits and show that a typical neutron star has a radius close to 11 kilometers. They also find that neutron stars merging with black holes are in most cases likely to be swallowed whole, unless the black hole is small and/or rapidly rotating. This means that while such mergers might be observable as gravitational-wave sources, they would be invisible in the electromagnetic spectrum.

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Jahed Abedi receives 2019 Buchalter Cosmology Prize – January 08, 2020

Dr. Jahed Abedi © J. Abedi

Jahed Abedi, a postdoctoral researcher at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), shares the $10,000 First Prize of the annual 2019 Buchalter Cosmology Prize with Niayesh Afshordi (University of Waterloo and Perimeter Institute for Theoretical Physics). The winners of the prize have been announced on 6 January 2020 at the 235th meeting of the American Astronomical Society in Honolulu.

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News from the Gravitational Universe – January 06, 2020

Numerical-relativity simulation of the binary neutron star coalescence and merger which resulted in the detected gravitational-wave event GW190425. The image shows the gravitational wave signal with colors ranging from red, yellow, green, blue with increasing strength, and the density of the neutron stars from light to dark blue ranging between 200 thousand to 600 million tons per cubic centimeter, respectively. © T. Dietrich (Nikhef), S. Ossokine, A. Buonanno (Max Planck Institute for Gravitational Physics), W. Tichy (Florida Atlantic University) and the CoRe-collaboration

The international gravitational-wave detector network has observed what is most likely its second signal from merging neutron stars. The signal dubbed GW190425 was identified as a highly significant event by the LIGO Livingston and the Virgo detector on April 25, 2019. The signal comes from a distance of about 520 million light-years, four times farther away than the first gravitational wave from a binary neutron star merger detected in August 2017. No observations by electromagnetic or neutrino observatories related to this signal have been reported. While a binary neutron star merger is the most likely explanation, the combined mass of the system is much higher than that of other known such systems. This could be due to special formation circumstances of the system. It is also possible that one or both objects are light-weight black holes not previously observed.

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NASA Award for AEI Researchers – December 12, 2019

The NASA Group Achievement Awards for the German LRI team.

A group of 47 researchers in Germany received a NASA award for their teamwork on the novel and very successful Laser Ranging Interferometer on board the GRACE Follow-On satellite tandem. Among them are 13 researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) and the Institute for Gravitational Physics at Leibniz Universität Hannover. The NASA Group Achievement Award was presented to the team at the Jet Propulsion Laboratory at the end of October for “dedication and excellence in developing and successfully deploying” the laser instrument on board the GRACE Follow-On mission.

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Squeezed Light Success at Virgo – December 05, 2019

The background noise of the gravitational-wave observatory Virgo without squeezed-light source (black line) and with squeezed-light source (red line). It reduces the noise at frequencies above 100 Hertz by up to one third and thus makes it possible to detect weaker gravitational waves. The blue line shows increased noise that occurs when the squeeze light source is used in a sense “the wrong way round”. © Virgo Collaboration, Vahlbruch, Mehmet, Lück, Danzmann

A squeezed-light source developed by researchers at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) for the Virgo gravitational-wave detector near Pisa has impressively demonstrated its capabilities in recent months. This is shown by the latest data published from the third observation run (O3) of the international detector network. The squeezed-light source reduces the dominant quantum mechanical detector background noise by about one third. This allows Virgo, for example, to detect gravitational waves from merging neutron stars up to 26% more frequently. The use of squeezed light also plays an important role for planned third-generation detectors such as the Einstein Telescope. The squeezed-light source was delivered and commissioned at the beginning of 2018. Since the start of O3 on April 1, 2019, it has provided significantly improved Virgo sensitivity.

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New Initiative to Explore the Origin and Future of the Universe – November 21, 2019

Cosmic evolution in a cyclic universe: the big bang is replaced by a bounce and our universe is born as a result of a smooth transition from an early epoch of contraction to the current expanding phase. © Anna Ijjas

Anna Ijjas, leader of the recently established Lise Meitner Research Group “Gravitational Theory and Cosmology” at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute / AEI) in Hannover, and Paul Steinhardt, Albert Einstein Professor in Science at Princeton University, receive 1.3 million US-dollars for four years from the Simons Foundation. The goal of the newly funded initiative “New Directions in Cosmology and Gravitational Theory” is to develop and test theories of the origin, evolution, and future of the universe that challenge the standard view that the universe began with a big bang about 14 billion years ago. Ijjas’ group at the AEI Hannover receives 500 000 US-dollars that she will use towards building her research team, including support for graduate students and postdocs, workshops, conferences, and visitors.

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Max Planck Director and Professor at Leibniz Universität Hannover honored – October 29, 2019

Fotoreportage über Prof. Dr. Karsten Danzmann, Direktor im Max-Planck-Institut für Gravitationsphysik ( Albert Einstein Institut ) inr Hannover am 8. Februar 2016

Prof. Karsten Danzmann, Director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover and Director of the Institute for Gravitational Physics at Leibniz University Hannover, has been accepted into the Manager Magazine’s “Hall of Fame of German Research”. The award recognizes his lifelong, outstanding contributions to the advancement of research. The award was presented on 29 October in Berlin.

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Pulsating gamma rays from neutron star rotating 707 times a second – September 19, 2019

A black widow pulsar and its small stellar companion, viewed within their orbital plane. Powerful radiation and the pulsar’s “wind” – an outflow of high-energy particles — strongly heat the facing side of the star to temperatures twice as hot as the sun’s surface. The pulsar is gradually evaporating its partner, which fills the system with ionized gas and prevents astronomers from detecting the pulsar’s radio beam most of the time. NASA’s Goddard Space Flight Center/Cruz deWilde

An international research team led by the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hannover has discovered that the radio pulsar J0952-0607 also emits pulsed gamma radiation. J0952-0607 spins 707 times in one second and is 2nd in the list of rapidly rotating neutron stars. By analyzing about 8.5 years worth of data from NASA’s Fermi Gamma-ray Space Telescope, LOFAR radio observations from the past two years, observations from two large optical telescopes, and gravitational-wave data from the LIGO detectors, the team used a multi-messenger approach to study the binary system of the pulsar and its lightweight companion in detail. Their study published in Astrophysical Journal Letters today shows that extreme pulsar systems are hiding in the Fermi catalogues and motivates further searches. Despite being very extensive, the analysis also raises new unanswered questions about this system.

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