نوشته شده توسط , ۱۱ شهریور ۱۳۹۶

سمینار ۱ : Cosmology with Sunyaev–Zel’dovich effect 

فاطمه رحیم منفرد (دانشکده فیزیک دانشگاه صنعتی شریف )

سمینار ۲ : The impact of near stellar flybys on the habitability of planets

بهزاد بجنوردی (دانشکده فیزیک دانشگاه صنعتی شریف )

 

Abstract of Seminar ۱: Observations of cosmic microwave background (CMB) and large scale structure show that standard model of cosmology LCDM  is consistent with observational data‎. ‎The standard model is defined by cold dark matter‎, ‎cosmological constant and also Gaussian initial conditions which are almost scale-invariant‎, ‎adiabatic and isotropic‎. ‎‎While this model is consistent with observational data‎, ‎there exist a couple of problems namely the problems of dark energy‎, ‎dark matter‎, ‎missing baryon and the physics of early universe‎. ‎One of the most recent methods to analyze cosmological models which is tightly associated with structure formation is the use of galaxy clusters distribution function and the effect of such structures on CMB photons‎. ‎Sunyaev-Zel’dovich effect (SZ) which is the effect of free hot electrons of galaxy clusters on CMB photons consists of two different physics i.e‎. ‎the thermal and the kinetic SZ effects‎. ‎It can provide valuable information about the amount of baryons in a cluster‎, ‎the mass of a galaxy cluster and its bulk velocity. In this thesis we will investigate the kinetic SZ effect and its correlation with other important characteristics of the velocity of the cluster to determine the ratio of baryonic matter to dark matter in a galaxy cluster‎. ‎Then we will investigate the thermal SZ effect to study the mass distribution of structures and its correlation to standard model and the possible deviation from it‎. ‎At the end we will study the two-point auto-correlation of this effect and the cross-correlation of this effect with other characteristics of the distribution of matter in cosmological models‎.

Abstract of Seminar 2:  With discovery of each exoplanet in habitable zone around a star, where we have the right properties of the star and the planet for supporting life at the present time, we expect to find life. But life is not born in a day; if our search is for advanced or intelligent type of life, there must be enough time for it to evolve and it takes billions of years. If the planet is ripped off of its life-supporting properties in midst of its evolution by a hazard, advanced species will not be born. My work is on the near stellar flyby hazard. I examine earth-like planets in different environments (spiral arms, galactic center, star clusters, elliptical galaxies and collisional galaxies) to calculate the chances for the planet to stay in the habitable zone in different periods of time needed for life to evolve to advanced stages of life.

 In this talk I will introduce the works done in this area and discuss the different outcomes of stellar flybys and how much is their chance in long periods of time in different environments. I will also show how it affects the chances of finding life in different regions of our galaxy and other galaxies.

 

یکشنبه ۱۲ شهریور ماه ۱۳۹۶، ساعت ۱۰:۰۰

دانشکده فیزیک، طبقه اول، کلاس فیزیک ۳

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