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SHAO Astrophysics Colloquium

Title: Ultra-compact dwarf galaxies (UCDs) in the Virgo cluster

Speaker: Chengze Liu (Shanghai Jiao Tong University)

Time: 3:00 pm, January 09 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: 

For many decades, it was widely believed that galaxies and star clusters were completely distinct populations. However, in the late 1990s, a new type of compact stellar system, Ultra-Compact Dwarf (UCD) galaxies, was discovered to have some properties that bridged the gap between compact, dwarf galaxies and globular clusters. Roughly 20 years after their discovery, the origin of UCDs remains surprisingly obscure. In this talk, I will present results for UCDs in the Virgo cluster based on imaging mainly from the Next Generation Virgo Cluster Survey (NGVS). We have identified more than 600 candidate UCDs from the cluster core to the virial radius. This is the largest and most homogeneous sample of UCDs presented to date for any cluster environment, and the first of its kind for the Virgo cluster. I will summarize the basic statistical properties of the UCD sample, compare to the GCs and nuclei, identify any special UCDs we found and give the observational constrains on the origin of UCDs.

 

Seminar talk

 

Title: GR effects in black hole accretion flows

Speaker: Andrzej Nied?wiecki

Time: 10:00 am, January 07 (Tuesday)

Location: xxx, 3rd floor

Abstract: I will discuss strong gravity effects relevant for the formation of X-ray spectra in the optically-thick as well as the optically-thin regime of black hole accretion, and results of investigation of these effects in several black hole systems: 1H0707-495, NGC 4151 and NGC 7213.

About the speaker: Andrzej Nied?wiecki is currently an associate professor at the Department of Astrophysics at the University of ?ód? (?ód?, Poland). From 1992 to 1997 he worked at the Copernicus Astronomical Center of the Polish Academy of Sciences in Warsaw, where he received the Doctoral Degree in 1996. In 1997 he moved to the University of ?ód?, where he got the habilitation in 2009. His scientific interests fall in two areas of high energy astronomy and astrophysics: (1) theoretical and observational investigation of accretion onto compact objects, and (2) experimental techniques of imaging Cherenkov telescopes (ICT). He is involved in two ICT experiments, MAGIC and CTA.

 

 
中心简介
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  天体物理研究室是上海天文台从事基础天体物理研究的主要机构,包括12个科研团组。研究室的研究方向涉及黑洞和高能天体物理、星系形成与演化、宇宙大尺度 结构、星团和银河系结构、恒星形成、以及行星天体物理等领域,在黑洞吸积与喷流理论、黑洞和星系的共同演化、银河系结构与动力学、计算天体物理等方向具有一定的国际影响力。研究室现有固定研究人员固定研究人员46名,博士后6名,研究生65名。固定研究人员中包括国家杰出青年基金获得者3人、优秀青年基金获得者2人、科学院“百人计划”入选者9人。
  研究室与国内外的天文研究机构有着密切的合作关系,与中国科技大学联合成立了“中国科学院星系和宇宙学重点实验室”,与厦门大学成立了天体物理联合中心。研究室还参与了多项国际、国内天文项目和观测计划,如LAMOST、HXMT、SDSS-IV、TMT、LSST、FAST等。
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