Special Lunch talk on Jan. 10th, 2019

Radial resolved galaxy disks models based on semi-analytic models of galaxy formation

Speaker: 孟晓磊（清华大学）/ Xiaolei Meng (Tsinghua University)

Venue: Gewu 4410

Time: 12:30 PM, Thursday, 10th January, 2018

Abstract:

The ultraviolet (UV) upturn phenomenon in elliptical galaxies has attracted much attention as it violates the common understanding that early type galaxies are mostly comprised of old stars with little UV radiation. Although there have been several recent samples of UV-upturn detections at low redshift (z<0.5), the analysis at high z is still lacking. In this work, we try to address this by measuring UV-upturn elliptical galaxies at 0.9<z<2.5 in 6 cluster fields, using the ultra deep broad-band photometry given by the Hubble Frontier Fields project. Ancillary data sets are also taken into account, such as the CLASH data, the Ultra-deep Ks-band Imaging of the HFF (KIFF project), etc. These data span 14-20 filters and cover far UV to H band for the target redshift range, offering more accurate photometric redshift estimation and SED fitting. Meanwhile, the spectroscopic data acquired by the Grism Lens-amplified Survey from Space (GLASS) and Multi Unit Spectroscopic Explorer (MUSE) observations are also included in the analysis for deriving spectroscopy redshift and excluding star-forming galaxies mistaken for passive ones. We obtained the distribution of UV-upturn elliptical galaxies over redshift and compared our observational results with the theoretical predictions given by the binary star model explaining the origin and evolution of this phenomenon. Especially we found that there exists a few UV-upturn elliptical galaxies at z>2 which hard to be explained by the binary star model on its own. More importantly, we managed to explore the distribution of specific UV-upturn radiative zone with galaxy radius in our sample.

Doodle: https://doodle.com/poll/qcn36rkxyfh2ridd