سمینار این هفته را خانم دکتر صدیقه سجادیان از دانشکده فیزیک دانشگاه شریف ارائه  خواهند کرد. عنوان و چکیدهٔ سمینار ایشان به شرح زیر است:

آشکارسازی و مشخصه‌یابی دیسک‌ها از طریق رصد قطبش‌سنجی از رویدادهای ریزهمگرایی گرانشی 

Detecting and characterizing circumstellar disks through polarimetry observations of microlensing events

Abstract: Circumstellar disks around the Galactic bulge stars are un-resolvable from their host stars and make a net polarization signal due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this project is to determine what extra information about these disks can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot disks which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. Although the polarimetric efficiency for detecting this kind of disks is similar to the photometric observation, but polarimetry observations can help to constraint the disk geometrical parameters e.g. the disk inner radius and the lens trajectory with respect to the disk semimajor axis. On the other hand, the time scale of polarimetric curves of these microlensing events generally increases while their photometric time scale does not change. Monte Carlo simulations also show that almost 4 optically-thin disks around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10 years monitoring of 150 million objects toward the Galactic bulge.

این سمینار در روز یکشنبه ۲۴ آبان ماه ۱۳۹۴، ساعت ۱۵ در کلاس فیزیک ۴  در طبقهٔ  اول دانشکدهٔ فیزیک برگزار خواهد شد.