Seminar 1: Data Analysis of Gaia and OGLE projects and determination properties of gravitational microlensing

Saeed Mazhab

Department of Physics, Sharif University of Technology

Seminar 2: Detecting primordial Black Holes with the help of 21-cm cosmology

Sajad Tabasi

Department of Physics, Sharif University of Technology

Abstract 1: In this project, we intend to examine the data related to gravitational microlens observed in the OGLE project and compare them with the data related to the GAIA project. Based on the comparison of the data recorded in both projects, we estimate the exact coordinates of the gravitational microlens and by comparing the light curves and matching the existing catalogs, according to the parallax, we can calculate the distance, mass and specific motion of the observed gravitational microlenses. In this process, we can determine how many different masses the observed microlens is due to, and among the investigated cases, objects with very high masses are considered black holes. Finally, by repeating this process and collecting enough data, the general result can be statistically analyzed. A similar research has been conducted in the past years by Dr. Sohrab Rahvar and Amirhossein Dehghani, and the results of this research can be used in the statistical analysis stage.

 

Abstract 2: Over time, the temperature of the intergalactic medium is highly sensitive to the physical mechanisms within it. Thus, any physical phenomenon can increase or decrease the temperature. Since primordial black holes can accrete and pull in the surrounding gas and cause them to radiate, if they are abundant enough, they will have the ability to seriously affect the temperature of the intergalactic medium. In this seminar, I will first show plots of the linear power spectrum by considering primordial black holes as dark matter and then its effect on the temperature of the intergalactic medium. In addition, I will explain how much the temperature of the medium increases for different masses of these black holes and for what masses the whole dark matter can be considered as primordial black holes. Finally, I will elaborate on a more realistic model and consider the nonlinear power spectrum, and in this regime, we can measure the effect of primordial black holes on the power spectrum. It is so important to see whether our radio observatories can detect such a power spectrum or if we should wait for the future!

یکشنبه 14 اسفند 1401، ساعت 17:30

Sunday 5 March 2023 – 17:30 Tehran Time

Hybrid Seminar

آمفی تئاتر دانشکده فیزیک-تالار جنابPhysics Department – Amphitheater- Jenab Hall/

https://vc.sharif.edu/ch/cosmology

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