Large Scale Structure: Our last chance to discover the hidden scenario of Early Universe
محمد انصاری (دانشکده فیزیک دانشگاه صنعتی شریف)
Abstract: The inflationary models solve several problems of cosmology, such as horizon problem and the flatness of the Universe. But however there are lots of inflationary models which Cosmic Microwave Background (CMB) can’t rule out them now. Non-Gaussianity and tensor perturbation are two complementary probes for inflationary models. This is because the inflationary models have different predictions for these two observables, however they are not detected yet. The deviation of the scale invariance of the primordial power spectrum is another opportunity which is detected by CMB data but with low statistical significance. In this presentation I will talk about the last opportunity and justify how Large Scale Structure will help us to rule out more inflationary models or the inflation scenario itself (through some idea about clock signal models which is developed recently).
Korea Astronomy and Space Science Institute, South Korea
Abstract: Strong gravitational lensing systems contain a wealth of information that can be used to estimate the expansion history of the universe. The light rays from different images of a source quasar experience different gravitational potentials and optical paths which result a time delay in the associated light curves. A reliable estimation of the time delay has crucial role in the process of expansion history estimation. In this talk we describe our proposed algorithm for time delay estimation which shows outstanding results in the Time Delay Challenge (TDC). This algorithm consists of the smoothing and cross-correlation methodologies as well as a quick way for error estimation. In continue we explain the modified version of this algorithm which recently we have developed. In this version we introduce a new time delay estimator which includes weighted cross-correlation and some other changes in the procedure of estimation. The modified algorithm shows more precise results on TDC simulated data. At the end we discuss the estimation of time delay related to the light curves of the lensed quasar SDSS J1001+5027 system and compare our results with the time delays obtained by different group of researchers for the same system.
We will have a Stellar Light Curve Analysis Workshop next week. Tuesday – Wednesday and Thursday 7- 8 – 9 day (27-28-29 December) from 8:00 to 16:00in Physics Department of Sharif University of Technology.
Instructors: Dr. Sedighe Sadjadian (SUT) and Dr. Farhang Habibi (LAL-IN2P3/CNRS).
In order to participate to this workshop you have to attend the preliminary session which will be held Sunday 5 day – 25 December @ 15:00 in Partovi Hall – Physics Department of SUT.
In order to participate to the workshop you have to send your email address to Miss Liaghi with email address: fatemehliaghi95-AT-gmail.com.
Preliminary knowledge of Astronomy and Computer skills (Linux , Python or/and C++ ) is desirable.
The workshop has no registration fee and accordingly the lunch and breaks are not supported.
Primordial Black Holes Formation from Particle Production during Inflation
انسیه عرفانی (دانشگاه تحصیلات تکمیلی علوم پایه زنجان)
Abstract: In this talk I will explain the possibility of primordial black holes (PBH) formation from particle production during inflation. We consider the scalar and the gauge quanta production in inflation models, where in the latter case, we focus in two sectors: inflaton coupled i) directly and ii) gravitationally to a U(1) gauge field. We do not assume any specific potential for the inflaton field. Hence, in the gauge production case, in a model independent way we show that the non-production of DM PBHs puts stronger upper bound on the particle production parameter. Our analysis show that this bound is more stringent than the bounds from the bispectrum and the tensor-to-scalar ratio derived by gauge production in these models. In the scenario where the inflaton field coupled to a scalar field, we put an upper bound on the amplitude of the generated scalar power spectrum by non-production of PBHs. As a by-product we also show that the required scalar power spectrum for PBHs formation is lower when the density perturbations are non-Gaussian in comparison to the Gaussian density perturbations.
From Supernovae, to Hypernovae to Binary Driven Hypernovae
Remo Ruffini
ICRANet, Pescara, Italy
Department of Physics and ICRA, University of Rome “La Sapienza”, Italy
Abstract: Our concept of Induced Gravitational Collapse (IGC paradigm) from an incipient Supernova into a companion Neutron Star, has unlocked the understanding of seven different families of GRBs, indicating the path for the formation of Black Holes in the Universe. An authentic laboratory of relativistic astrophysics has been unveiled in which new paradigms have been introduced in order to advance in the knowledge of the most energetic, distant and complex systems of our Universe. A novel paradigm of the Cosmic Matrix has been introduced which parallel, in a relativistic cosmic level, the concepts of an S Matrix introduced by Feynman, Wheeler and Heisenberg in the quantum world of microphysics. Here the “in” states are represented by a Neutron Star and a Supernova, the “out” states, generated, in less than a second, by a new Neutron Star and a Black Hole. This novel field of research needs very powerful technological observations in all wavelength ranging from Radio, to Optical, to X and Gamma radiation all the way to ultra-high-energy cosmic rays.
Power spectrum and halos number density in spherical collapse model
طیبه نادری (دانشکده فیزیک دانشگاه صنعتی شریف)
Abstract: We will consider what is perhaps the simplest model for the formation of non-linear (gravitationally bound) structures. Imagine that, we have a spherical region with density higher than the density of the background (which is equal to the critical density). According to general relativity, the evolution of this spherical overdensity will be independent of the background evolution, so that it will evolve exactly like a sub-universe with density higher than the critical density.
علیرضا طالبیان اشکذری (دانشکده فیزیک دانشگاه تهران)
Abstract: We study the evolution of the “non-perturbative” metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized “Separate Universe” approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the δM formalism for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so-called δN formula for the superhorizon dynamics of the curvature perturbations. Likewise its ancestor, δN formalism, this new method can substantially reduce the amount of calculations related to the evolution of the tensor modes.
