今天是   收藏本站 | 联系我们 | 上海天文台 | English
首页 研究领域 研究团组 科研人员 学术活动 工作机会 内部信息
  每周简讯
 
2014/12/1-2014/12/5

12/1-12/5

SHAO Astrophysics Colloquia

The Ages, Metallicities and Element Abundance Ratios of Massive Quenched galaxies at z~1.6  

Speaker: Nobuo Arimoto, Subaru Telescope (NAOJ)

Time: Monday, 3:00pm, December 1

Location: Lecture Hall, 3rd floor 

  

Abstract: We investigate the stellar population properties of a sample of 24 massive quenched galaxies at 1.25 < z < 2.09 identified in the COSMOS field with our Subaru/MOIRCS near-infrared spectroscopic observations. Tracing the stellar population properties as close to their major formation epoch as possible, we try to put constraints on the star formation history, post-quenching evolution, and possible progenitor star-forming populations for such massive quenched galaxies. By using a set of Lick absorption line indices on a rest-frame optical composite spectrum, the average age, metallicity [Z/H], and alpha-to-iron abundance ratio [alpha/Fe] are derived as log(age/Gyr) = 0.18 ± 0.05, [Z/H] = 0.08 ± 0.08, and [alpha/Fe] = 0.36 ± 0.09, respectively. Pure passive evolution to z = 0 brings the <z> = 1.6 quenched galaxies to the parameters in excellent agreement with local counterparts at similar stellar velocity dispersions, which qualifies them as progenitors of local massive early-type galaxies. Redshift evolution of stellar population ages in quenched galaxies combined with the low redshift measurement from the literature suggests a formation redshift of z ~ 2.5 around which the bulk of stars in these galaxies have been formed. The measured [alpha/Fe] value indicates a star formation time scale of < 350 Myr, which can be translated into a specific star formation rate of ~3 Gyr -1 prior to the quenching. Based on these findings, we discuss possible progenitor star-forming galaxies at z ~ 2.5 and find normal star-forming galaxies, i.e, those on the star-forming main sequence, followed by quenching event invoked by some internal mechanisms as likely precursors of quenched galaxies at <z> = 1.6 presented here.

  

Seminar talk

Title: Mid-Infrared Selected Dust-Rich Quasars: Recovering the Extended Quasar Population 

Speaker: Y. Sophia Dai Caltech-IPAC 

Time: Tuesday,2:00pm, Dec 2 

Location: the big conference room

 

Abstract: Quasars are shining beacons in the universe that enlightens us of the path to galaxy formation and evolution. However, there is no consensus on the physics of how quasars and their host galaxies interact. The statistical properties of quasars are therefore of critical values to our understanding of how the universe evolves to its present form, and what physical processes were involved in the active galaxy evolution stage. While many quasar samples to date underlines the point-source nature of unobscured quasars, we select an isotropic quasar sample, a 'dust-rich' population, based on Spitzer MIPS flux and MMT spectroscopy. I will present the results of the study, including the recovery of a significant subgroup of extended objects, the implications on quasar-host connections, as well as ongoing efforts to study the obscuration via absorption features 

  

Group meetings and additional talks

SHAO SDSS-IV meeting
Location: Middle conference room, 3rd floor
Time: Tuesday, Dec 2
13:20 - 14:20 Characterising Ionised Gas Outflows in SDSS Quasars (Ramya) 

14:30 - 14:40  MaNGA email update (Ting Xiao) 

14:40 - 15:30  P-MaNGA: Full spectral fitting and stellar population maps from prototype observations (Lin Lin) 

15:40 - 16:15  Exploring the kinematic Properties of [OIII]5007 in AGN Hosts Using MaNGA Data (Weizhe Liu) 

  

Observational High Energy Astrophysics Group Seminar 

Location: 1401; Contact: Zhen Yan <zyan@shao.ac.cn>

Title: Keck II spectroscopy of mHz quasi-periodic oscillations in Hercules X-1(Lin Jie)

The slim-disk state of the ultraluminous X-ray source in M8( Wenda Zhang)

X-ray outbursts from a new transient in NGC 55(Zhang Hui)

Time: Monday, 10:30am,Dec 1 

  

Radio Astrophysics Group Seminar

Location: 1617; Contact: Guangrui Yao < gryao@shao.ac.cn> 

Title: Water Megamasers and their application in astrophysical measurements 

Speaker: Feng Gao

Time: Tuesday, 11:30am, Dec 2 

 

Black hole accretion and high energy group

Location: 1608; Contact: Qixiang Yang < qxyang@shao.ac.cn>

Title: High accretion rates in magnetised Keplerian discs  mediated by a Parker instability driven dynamo

Speaker: Defu Bu

Time: Friday, 10:00am, Dec 5

附件下载
©2008-2013 中国科学院上海天文台 版权所有
地址:上海市南丹路80号 邮编:200030 邮件:shao@shao.ac.cn