北京大学科维理天文与天体物理研究所

Featured Science

FAST Reveals a Dynamically Evolving Environment Around a Repeating Fast Radio Burst Sourc...

In a Nature paper published on 21 September 2022, the FAST FRB team reported using FAST to monitor FRB 20201124A for about 2 months. They analyzed 1,863 bursts of FRB 20201124A detected by FAST in totally 84-hour observations obtained across 54 days, which is the largest sample of bursts recorded with polarization information so far. The high event rate makes FRB 20201124A among the most active known FRBs. They discovered several phenomena never detected before, the irregular short-time variation of the Faraday rotation measure, which probes the line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant value; they witnessed the quenching of the burst activity on a timescale shorter than three days; they detected prominent circular polarization in these bursts (up to 75%); they detected ooscillations in fractional linear and circular polarizations as well as polarization angle as a function of wavelength. Sensitive optical observations to the host galaxy of FRB 20201124A using the Keck 10m optical telescopes revealed that the host galaxy is a Milky-Way-sized, metal-rich, barred spiral galaxy, where the FRB source resides in a low stellar density, interarm region at an intermediate galactocentric distance.

PKU astronomers discover nearly 200 new quasars behind the Galactic plane

An international research team led by astronomers from Peking University has identified 204 quasars behind the Galactic plane, 191 of which are new discoveries, using five optical telescopes in China, USA, and Australia. The new research, recently published in the Astrophysical Journal Supplement Series (ApJS), marks the successful lift-off of the spectroscopic observation campaign, after releasing the candidate catalog of quasars behind the Galactic plane with more than 160,000 sources previously selected by this team.

What Reionized the Universe?

A team of astronomers, led by Professor Linhua Jiang at the Kavli Institute for Astronomy and Astrophysics and School of Physics at Peking University, has revealed that distant quasars or galactic nuclei with actively growing supermassive black holes made a negligible contribution of ionizing photons to cosmic reionization 13 billion years ago. This finding settles a long-standing issue about the quasar contribution to cosmic reionization, and suggests that galaxies are the major energy sources. The result was recently published as an article in Nature Astronomy on June 16, 2022.

Astronomers reveal first image of the black hole at the heart 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 workings of such giants, which are thought to reside at the centre 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. This effort involved three scientists affiliated with Peking University, including the Director and University Chair Professor Luis C. Ho and Assistant Professor Lijing Shao from the Kavli Institute for Astronomy and Astrophysics, and Assistant Professor He Sun from the College of Future Technology.

World-wide radio telescope network strengthens evidence for signal that may hint at ultra...

The International Pulsar Timing Array (IPTA), a team of astronomers and astrophysics from several collaborations from around the world, has recently announced the results of a comprehensive search for low-frequency gravitational waves (GWs) in their most recent official data release, known as Data Release 2 (DR2).

Towards the Detection of the Nanohertz Gravitational-wave background: The European Pulsa...

EPTA is a scientific collaboration bringing together teams of astronomers around the largest European radio telescopes, as well as groups specialized in data analysis and modelling of gravitational wave (GW) signals. It has published a detailed analysis of a candidate signal for the since-long sought gravitational wave background (GWB) due to in-spiraling supermassive black-hole binaries. Although a detection cannot be claimed yet, this represents another significant step in the effort to finally unveil GWs at very low frequencies, of order one billionth of a Hertz. In fact, the candidate signal has emerged from an unprecedented detailed analysis and using two independent methodologies. Moreover, the signal shares strong similarities with those found from the analyses of other teams. The results were made possible thanks to the data collected over 24 years with five large-aperture radio telescopes in Europe.