INAF - Astronomical Observatory of Padova

INAF - Astronomical Observatory of Padova is one of the main structures of the National Institute of Astrophysics (INAF). The main activity of the Observatory is to perform scientific research in various  fields of Astrophysics. The Observatory also contributes to  advanced education, assists in the dissemination of knowledge and implements project of education and outreach of Astronomy.

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INAF - Osservatorio Astronomico di Padova


Seminario Dr. Tadayuki (Taddy) Kodama
15.07.2019 - 15.07.2019
Aula L. Rosino - Dipartimento di Fisica ed Astrono - Padova



Lunedi 15 Luglio 2019, h. 11:30 

 Aula L. Rosino Dipartimento di Fisica e Astronomia

Tadayuki (Taddy) Kodama 

Astronomical Institute, Tohoku University

Panoramic views of galaxy cluster formation and evolution



Our Mahalo-Subaru project, a systematic narrow-band line emitter survey, has mapped out star formation activities in and around galaxy clusters over the cosmic times and revealed the inside-out quenching of star formation activities from cluster cores to the surrounding regions as time progresses.
  In the dense cores of a cluster at the cosmic noon (z=2.5), we see an enhancement of star forming activities, which are likely driven by ample gas that is supplied by massive gas inflow through the filamentary structures. It is consistent with strong Lya line attenuations with respect to the Ha emission lines as indicated by dual narrow-band imaging (Lya and Ha), and also with higher molecular gas mass fraction as observed by ALMA.
  Together with the results on X-ray clusters at similar redshifts in the literature where they find a deficit of gas while star formation efficiency tends to be higher in the cluster cores, we argue that the gas accretion mode may be changed from the cold accretion mode accompanied by high star formation activity, to the hot mode where gas cooling and thus accretion to galaxies become inefficient, resulting in the quenching of the cluster cores.
  Furthermore, I will introduce our on-going, large, panoramic distant cluster program using Hyper Suprime-Cam (HSC) on Subaru, called HSC^2. We take a hybrid method in finding distant clusters; one is the conventional red sequence technique based on multi-photometry data, and the other is the narrow-band line emitter imaging survey. This way we can not only trace old, passively evolving galaxies, but also younger
star-forming galaxies, and thus the sampling bias of clusters is largely mitigated. Based on this unique sample, we track down the history of mass assembly and star formation in and around clusters all the way from the cosmic noon (z~1.7) down to z~0.4.


Aula L. Rosino - Dipartimento di Fisica ed Astrono
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