سمینار امروز را خانم فاطمه باقری از دانشکده فیزیک دانشگاه شریف و آقای امیر ملازاده از دانشکده فیزیک دانشگاه خوارزمی ارائه  خواهند کرد. عنوان و چکیدهٔ سمینار ایشان به شرح زیر است:

Seminar 1: Too Big To Fail?

Seminar 2:  Degeneracy between bias and Dark energy equation of state, is weak lensing a solution?

Seminar 1- Abstract:   Over and over again, new observations come in that match the predictions of ΛCDM. But there are still a few anomalies that bug us, especially on relatively small (galaxy-sized) scales. One such anomaly is the “too big to fail” problem. In this talk, first, I will explain what this problem exactly is and then I will briefly review some solutions have been found to explain it so far.

Seminar 2-Abstract:  The nature and the properties of Dark Energy are among the most significant unsolved problems in physics. We now know that Dark Energy accounts for about 70% of the energy density of the Universe and is causing the cosmic expansion to accelerate. But there exist only very few observational windows into the properties of this phenomenon. Measurements of the Integrated Sachs-Wolfe effect (ISW) provide a powerful method to probe Dark Energy, as this effect is sensitive to the time evolution of the gravitational potential sourced by Large Scale Structure. One interesting feature of several of the previous studies is that the cross correlation signal lies above the predicted value in the standard cosmological model (in which the Dark Energy is a Cosmological Constant). We could show a dark energy with redshift dependent equation of state ( w_0 + w_a*(1/(1+z)) ) is a good fit to data, but if we change our assumption about a “constant bias” and use a redshift dependent bias LambdaCDM is still a good fit too! Here is the question: Redshift dependent bias or varying with time equation of state. We think weak lensing can break this degeneracy!

این سمینار امروز یکشنبه ۱۱ بهمن ماه ۱۳۹۴، ساعت ۱۵ در اتاق ۵۱۷  در طبقه پنجم دانشکدهٔ فیزیک برگزار خواهد شد.