Research Highlights and News

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Understanding neutral hydrogen clustering during re-ionization

Upcoming observations of cosmic radio signals will mark the beginning of a new era in cosmology as they will provide a first glance on the neutral hydrogen distribution in the early universe. These observations will give us insights into a key process in the evolution of the universe – the reionization of the neutral hydrogen by the first stars and galaxies. The neutral hydrogen distribution can be observed via photons, which are emitted by neutral hydrogen atoms at the wavelength of 21cm and are redshifted to radio signals during their journey through the expanding universe before being observed on earth.


Neutron Stars, viewed through Photons, Gravitational Waves and Neutrinos

On the night of March 30th, 2018, the 21st session of the "New Worlds, New Horizons" Public Lecture series was held in the Auditorium of Tsinghua University. The lecture was delivered by Prof. Peter Mascaros, Abelli Chair Professor of Astronomy and Astrophysics of Pennsylvania State University. Nearly 300 people from Tsinghua University and elsewhere attended the lecture.


A MaNGA view of how galaxies distribute in the mass-size plane

The universe houses hundreds of billions of galaxies with different color, sizes and morphologies. As seen in the Hubble Ultra-Deep Field (Figure 1): some galaxies appear to be red, nearly featureless and elliptical, while some have beautiful and blue spiral arms (spiral galaxies). Surprisingly these diverse galaxies follow simple global scaling relations. Recent work led by an PhD student, Hongyu Li (NAOC), Profs. Shude Mao (Tsinghua) and Michele Cappellari (Oxford) extended such scaling relations using spatially-resolved integral field unit data from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of the world-leading SDSS surveys. This study provides further constraints on how galaxies form and evolve.


THCA year-end meeting and AMD Award for graduate students

Monday 22nd of January, 2018, THCA held the 2017 year-end meeting. Graduate students and faculty members at THCA were invited to attend this yearly event. The meeting started at 9:00am with a two-hour session for graduate students to give oral presentations, summarizing their scientific research in 2017. As a result of this session, eight of the graduate students received the AMD Award for their significant progress made over the past year, as selected by a committee formed by six professors from THCA. A ceremony was then held for the awardees after a short Pizza party. Ms. Ping Le, Director of University Relations Division of the Advanced Micro Devices (China) Co., Ltd., donor of the Award, was invited to THCA for both the Pizza party and the award ceremony.


MaNGA reveals how galaxies stop forming stars

Our understanding of the galaxy populations at both low-z and high-z has advanced dramatically, thanks to the large photometric/spectroscopic surveys of galaxies accomplished in the past one and a half decades. It's well established that the galaxies can be divided into two major populations in the space of stellar mass (or luminosity) and color. In addition, the fraction of the red population has steadily increased by a factor of two since redshift of unity, indicating that the star formation cessation in galaxies has been an important process driving the galaxy evolution in the past ~80 Gyr. However, how the star formation gets shutdown and what processes drive the star formation cessation are not fully understood. Processes internal to individual galaxies (e.g. secular evolution driven by bars or minor mergers, AGN feedback, etc.) and external environmental effects (e.g. tidal stripping and ram-pressure stripping) are both believed to play important roles. Therefore, in order to have a complete picture of the star formation cessation, one would need to have deep imaging and spatially resolved spectroscopy for a large sample of galaxies covering wide ranges of galaxy properties and environment. Such samples have become available only recently from the integral field spectroscopy (IFS) surveys.


Black Hole and AI: the Insight-HXMT Satellite

Tsinghua University "New World - New Horizon" twentieth astronomy public series lecture, "black hole and artificial intelligence: the Insight-HXMT satellite", was held in the evening of November 10, 2017 in the auditorium. The speaker was professor Tipei Li from Tsinghua University, academician of CAS. more than 500 interested students and professors attended the lecture.