北京大学科维理天文与天体物理研究所

Featured Science

Quasar Monster Black Hole Found in the Early Universe

Astronomers have discovered the second most distant quasar ever found, using the international Gemini Observatory and Cerro Tololo Inter-American Observatory (CTIO), Programs of NSF’s NOIRLab. It is also the first quasar to receive an indigenous Hawaiian name, Pōniuā’ena. The quasar contains a monster black hole, twice the mass of the black hole in the only other quasar found at the same epoch, challenging the current theories of supermassive black hole formation and growth in the early Universe.

Feeling the drag

Within a hierarchically evolving Universe, binary black holes (BBHs) are expected to form through galaxy mergers. How these BBHs merge is, however, still under debate. Xian Chen and collaborators show that Poynting–Robertson (PR) drag, a radiative process whose effects are observed in the interaction between the Sun and dust in our Solar System, is applicable to BBHs and can play an important role in shrinking their orbits sufficiently for them to merge.

Off the beaten path: a new framework for cold filament formation in galaxy clusters

Mon, 2020-05-04Using state-of-the-art radiation-hydrodynamic simulations, KIAA postdoctoral fellow Dr. Yu Qiu and collaborators proposed a new framework for cold gas filament formation, shedding light on how cold gas exists immersed in the hot, X-ray-emitting plasma permeating galaxy clusters.

When the Stars Align — the First Resolved Microlensed Images

Using VLTI GRAVITY, an international team led by Professor Subo Dong (KIAA) have resolved the two images of a microlensed source star for the first time, more than a century after Einstein first predicted that such image splitting could be caused by the gravity of another (lens) star along the line of sight to the source. This detection fills in the key missing ingredient that yields the mass and distance of the lens star. This technique could be applied in the future to measure the mass of isolated (single) stellar-mass black holes, which have so far remained elusive.

A New Look at an Old Problem: How to Measure Star Formation Rates in Galaxies

Using a large sample of galaxies from the Sloan Digital Sky Survey (SDSS), Ming-Yang Zhuang and Luis C. Ho from the Kavli Institute for Astronomy and Astrophysics at Peking University proposed an updated star formation rate (SFR) calibration using the [O II]λ3727 emission line for star-forming galaxies. Based on photoionization models, they extended the [O II]-based SFR estimator to active galaxies. This work has been published in The Astrophysical Journal (Zhuang & Ho 2019, ApJ, 882, 89).

Discovery of a new Luminous Blue Variable in the outskirt of the Andromeda Galaxy

A study by the research group led by Prof. Huawei Zhang from Department of Astronomy, Peking University and collaborators from Yunnan University report the discovery of a new Luminous Blue Variable (LBV) in the outskirt of the Andromeda Galaxy (M31), using data from the LAMOST spectroscopic surveys, from the Xinglong NAOC 2.16m, Lijiang YNAO 2.4 m optical telescopes and Hale 5m telescope, as well as archival data. The finding has been published in The Astrophysical Journal Letters.