A.U. Sıddiki; "Warped Disks in Galactic Nuclei: From Nearby AGN to the Galactic Center", Oct. 21, 10:40, FASS G056
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  • A.U. Sıddiki; "Warped Disks in Galactic Nuclei: From Nearby AGN to the Galactic Center", Oct. 21, 10:40, FASS G056

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 Faculty of Engineering and Natural Sciences
SEMINAR ANNOUNCEMENT

 

Warped Disks in Galactic Nuclei: From Nearby AGN to the Galactic Center
Ayşe Ulubay Sıddıki, Max Planck Institute for Extraterrestrial Physics

 

Many galactic nuclei, including our own, harbor supermassive black holes (SMBHs) which are surrounded by disks of gas and/or stars. Under certain circumstances, these disks may deviate from planar geomery, and become warped. In the case of gaseous disks, this modification to the shape of the disk might have consequences on the classification of AGN, and for stellar disks it might provide clues on the paradox of young stars in the very vicinity of a SMBH.

 

In this talk, I will discuss the effects of self-gravity on the dynamics of such warped disks. I will first introduce the theoretical framework, and then propose a new formation scenario for the mutually inclined disks of young stars observed at the Galactic Center.

 

October 21, 10:40, FASS G056

 

Inferring the Transport Properties of Edge-States Formed at  Quantum Hall based Aharonov-Bohm  Interferometers  Theoretically


Dr. Afif Sıddıki, Muğla University

 

Recent low-temperature transport experiments, utilizes the quantum Hall based interferometers to investigate the quantum nature of particles. Particularly, the Aharonov-Bohm (AB) interference experiments became a paradigm [1,2], which infers the AB phases of both the electrons and the quasi- particles. The single particle edge-state picture is used to describe transport, meanwhile electrostatics is enriched by interactions and both are used to explain the observed AB oscillations [2]. However, the actual spatial distribution of the edge-states is still under debate for real samples, since handling the full electrostatics is a formidable task, although, several powerful techniques are used [3]. By full electrostatics we mean both handing the crystal growth parameters and the "edge" definition of the interferometer, /i.e/. gate, etched or trench-gated.

 

In this talk, I provide a semi-analytical scheme to model AB interferometers induced on a two dimensional electron gas (2DEG) by solving the 3D Poisson for the given hetero-structure [4]. Our
calculation scheme also takes into account the lithographically defined surface patterns to obtain the electron and potential distributions under quantized Hall conditions [5]. The distinct part of our
calculation is that we can handle both gate and etching defined geometries. Our findings show that the etching defined samples provide a sharper potential profile than that of gate defined [6]. In addition we can define the structure with trench gating, which is the case for the experiments, and show that the formation of the edge-states is strongly influenced.

 

[1] F. E. Camino, W. Zhou, and V. J. Goldman, Phys. Rev. Lett. *95*, 246802 (2005).
[2] F. E. Camino, W. Zhou, and V. J. Goldman, Phys. Rev. Lett. *98*, 076805 (2007).
[3] S. Ihnatsenka and I. V. Zozoulenko, Phys. Rev. B *76*, 045338 (2007).
[4] A. Weichselbaum and S. E. Ulloa, Phys. Rev E *68*, 056707 (2003).
[5] S. Arslan, E. Cicek, D. Eksi, S. Aktas, A. Weichselbaum, and A. Siddiki, Phys. Rev. B *78*, 125423 (2008).
[6] A. Siddiki and F. Marquardt, Phys. Rev. B, *75*, 045325 (2007).

 

October 21, 11:40, FASS G049