Search for Missing Baryons Through Scintillation

, Ph.D. Dissertation Sharif University of Technology Habibi, Farhang (Author) ; Moniez, Marc (Supervisor) ; Rahvar, Sohrab (Supervisor)

Abstract

Aims: Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected at a longer time scale when the light of remote stars crosses an interstellar molecular cloud, but it has never been observed at optical wavelength. In a favorable case, the light of a background star can be subject to stochastic fluctuations on the order of a few percent at a characteristic time scale of a few minutes. Our ultimate aim is to discover or exclude these scintillation effects to estimate the contribution of molecular hydrogen to the Galactic baryonic hidden mass. This feasibility study is a pathfinder toward an observational strategy to search for scintillation, probing...

Searching for galactic hidden gas through interstellar scintillation: the OSER project

, Article Proceedings of Science, 18 August 2008 through 22 August 2008, Stockholm ; 2008 ; 18248039 (ISSN) Moniez, M ; Ansari, R ; Habibi, F ; Sharif University of Technology

2008

Abstract

Considering the results of baryonic compact massive objects searches through microlensing [1], cool molecular hydrogen (H2 - He) clouds should now be seriously considered as a possible major component of the Galactic hidden matter. It has been suggested that a hierarchical structure of cold H 2 could fill the Galactic thick disk [8] or halo [3], providing a solution for the Galactic hidden matter problem. This gas should form transparent "clumpuscules" of ∼ 10 AU size, with a column density of 1024-25cm-2, and a surface filling factor smaller than 1%. The OSER project (Optical Scintillation by Extraterrestrial Refractors) is proposed to search for scintillation of extra-galactic sources...

Understanding EROS2 observations toward the spiral arms within a classical Galactic model framework

, Article Astronomy and Astrophysics ; Volume 604 , 2017 ; 00046361 (ISSN) Moniez, M ; Sajadian, S ; Karami, M ; Rahvar, S ; Ansari, R ; Sharif University of Technology

EDP Sciences 2017

Abstract

Aims. EROS (Expérience de Recherche d'Objets Sombres) has searched for microlensing toward four directions in the Galactic plane away from the Galactic center. The interpretation of the catalog optical depth is complicated by the spread of the source distance distribution. We compare the EROS microlensing observations with Galactic models (including the Besançon model), tuned to fit the EROS source catalogs, and take into account all observational data such as the microlensing optical depth, the Einstein crossing durations, and the color and magnitude distributions of the catalogued stars. Methods. We simulated EROS-like source catalogs using the HIgh-Precision PARallax COllecting Satellite...

Search for turbulent gas through interstellar scintillation

, Article Proceedings of the International Astronomical Union ; Volume 7, Issue S285 , 2011 , Pages 376-378 ; 17439213 (ISSN) ; 9781107019850 (ISBN) Moniez, M ; Ansari, R ; Habibi, F ; Rahvar, S ; Griffin R. E ; Hanisch R. J ; Seaman R. L ; Sharif University of Technology

2011

Abstract

Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected when the light of remote stars crosses a Galactic - disk or halo - refractive medium such as a molecular cloud. We present the promising results of a test performed with the ESO-NTT, and consider its potential

Calculation of Interfacial Tension in Water-Methane System at High Pressures Using Molecular Simulation

, M.Sc. Thesis Sharif University of Technology Salami, Hossein (Author) ; Ghotbi, Cyrus (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Robert, Marc (Supervisor)

Abstract

Interfacial tension has wide application in surface engineering and specially oil and gas industry. One has to do work to transfer a molecule from bulk to the surface of a fluid. The amount of this work is proportional to Interfacial tension.Molecular simulation is a fundumental approach for calculating the thermophisycal properties of matter such asInterfacial tension.In this thesis we have investigated the effect of pressure and temperature on surface tension of pure water and interfacial tension of Water-Methane system. The TIP4P potential model was used for Water molecules and OPLS for Methane molecules. In the first part, Water heat capacity and Methane density were calculated for...

Investigation the Optimum Condition for Gas Injection into the Oil Reservoirs by Measuring the Interfacial Tension

, M.Sc. Thesis Sharif University of Technology Roham, Mohammad (Author) ; Ghotbi, Cyrus (Supervisor) ; Robert, Marc (Supervisor) ; Taghikhani, Vahid (Supervisor)

Abstract

Interfacial Tension (IFT) as a main parameter for gas flooding efficiency in oil reservoirs depends highly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this parameter at real reservoir condition for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs in crude oil-flue gas systems at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) of crude oil/flue gas and crude oil/N2 systems at different temperature levels are determined by applying vanishing interfacial tension (VIT) technique. Then, the effect of oil...