Gravitational wave detectors, LIGO and Virgo, have detected a population of massive black holes whose origin is one of the biggest mysteries in modern astronomy. According to one hypothesis, these objects may have formed in the very early Universe and may compose dark matter, a mysterious substance filling the Universe. A team of scientists from the OGLE (Optical Gravitational Lensing Experiment) survey from the Astronomical Observatory of the University of Warsaw have announced the results of nearly 20-year-long observations indicating that such massive black holes may comprise at most a few percent of dark matter. Another explanation, therefore, is needed for gravitational wave sources. The results of the study were published in two articles, in Nature and the Astrophysical Journal Supplement Series.

Professors Andrzej Udalski from the Astronomical Observatory of the University of Warsaw and Joachim Wambsganss from Centre for Astronomy of Heidelberg University have become the laureates of the prestigious 2024 Copernicus Award, granted by the Foundation for Polish Science (FNP) and the Deutsche Forschungsgemeinschaft (DFG), for their groundbreaking contributions to astrophysics through their collaborative research on gravitational microlensing and the discovery of exoplanets.

Astrophysicists at the H.E.S.S. Observatory in Namibia, in which researchers from the University of Warsaw are involved, have discovered the highest energy gamma rays ever from the Vela pulsar. The project at UW is coordinated by Prof. Tomasz Bulik from the Astronomical Observatory. The results of the research have been published in the journal “Nature Astronomy”.

An international team of astronomers has announced the discovery of an unusual white dwarf star that is made of hydrogen on one side and helium on the other. They reported their findings in the latest issue of Nature. Dr Przemysław Mróz from the Astronomical Observatory is a co-author of the study.

Today marks the beginning of a new era in the history of gravitational wave astronomy. Four groups studying pulsar timing have announced the results of their analysis of pulsar observations spanning the past few decades. Simultaneously, there have been announcements from the Parkes Pulsar Timing Array, European Pulsar Timing Array, NanoGrav in North America, and the Indian Pulsar Timing Array.

An international team led by astronomers from the Max Planck Institute for Extraterrestrial Physics has announced the discovery of a unique binary star system in which matter flows onto the white dwarf from its companion. The system was found due to bright, so-called super-soft X-rays, which originate in the nuclear fusion of the overflowed gas near the surface of the white dwarf. The unusual thing about this source is that it is helium and not hydrogen that overflows and burns. The paper presenting the results of this study has been published in the Nature journal. Optical observations of the system collected by the OGLE project led by prof. Andrzej Udalski from the Astronomical Observatory of the University of Warsaw – co-author of the paper – played an important role in its characterization.

The stars circle each other every 51 minutes, confirming a decades-old prediction.

Nearly half the stars in our galaxy are solitary like the sun. The other half comprises stars that circle other stars, in pairs and multiples, with orbits so tight that some stellar systems could fit between Earth and the moon.

An international group of astronomers with the participation of scientists from the Astronomical Observatory of the University of Warsaw discovered a “dormant” stellar-mass black hole in the Large Magellanic Cloud, a neighbor galaxy to our own. It is the first object of this type found outside the Milky Way. The discovery was made thanks to six years of spectroscopic observations obtained with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT) and nearly 20 years of photometric observations carried out as part of the Polish OGLE project with the Warsaw Telescope in Chile.

The Milky Way galaxy is expected to host over 100 million isolated black holes. Two independent teams of scientists, including astronomers from the Astronomical Observatory of the University of Warsaw, have for the first time discovered what may be a free-floating black hole.

Illustration of a close-up look at a black hole drifting through our Milky Way galaxy. The black hole is the crushed remnant of a massive star that exploded as a supernova. The surviving core is several times the mass of our Sun. The black hole traps light due to its intense gravitational field. The black hole distorts the space around it, which warps images of background stars lined up almost directly behind it. This gravitational “lensing” effect offers the only telltale evidence for the existence of lone black holes wandering our galaxy, which may be a population of 100 million.
(Credit: NASA, STScI, image: FECYT, IAC).

An international team of astronomers found evidence for a unique pair of supermassive black holes orbiting each other in the center of a quasar. Dr Przemysław Mróz from the Astronomical Observatory of the University of Warsaw is one of the co-authors of the study published in The Astrophysical Journal Letters.

Caught in an epic cosmic waltz 9 billion light-years away, two supermassive black holes appear to be orbiting around each other every two years. The two massive bodies are each hundreds of millions of times the mass of our sun and span a distance roughly fifty times the size of our own solar system. When the pair merge in roughly 10,000 years, the titanic collision is expected to shake space and time itself, sending gravitational waves across the universe.