Ph.D.

Now it is November 2008!
I start to plan all the way for my Ph.D. thesis
The general title will be accelerating universe:Theory and phenomenology.
In this work I should take a look and do my research in theoretical models generally Dark energy and modified gravity ones,and also use cosmological observations like Supernova, CMB,large scale structure,local tests of gravity to investigate the mystery of 70% of our universe.
I think that I should finish my work in September 2011!!!
It seems interesting time for me.
Go on...

Scintillation of light curves and Dark matter

In the last two weeks, in physics department of SUT, in our weekly cosmology seminars we have Frahang Habibi as a speaker. In this two sessions he describes for us a general view of his Ph.D thesis. Farhang is a joint Ph.D. student of sharif university and IAP in Paris.
He is working on dark matter detection in form of hydrogen molecule gas.

Now what is the story?
As we know 23% of our universe is composed of dark matter/means no electromagnetism interaction/but gravitationally is resemble to ordinary baryonic matter.
There are many many candidates for Dark matter starting from super symmetric particles to unseen baryonic matter.
Now what is Farhangs and Mark Moniez/his french side supervisor/ idea ?It is about a cloud of hydrogen molecule distrubeted in clusters which are not radiating because of there internal structure of hydrogen molucule ,but can be a candidate of unseen matter.
In this thesis they introduce a type of a test in order to detect them.
If there is a cloud of hydrogen molecules, they can effect optically on the light coming from stars beyond it.This cloud can scatter and diffract the light coming.So if in an experiment / observation/we can see an effect of scintillation in the light curves of the stars., it shows that there is something there that cause the amplification of light and maybe if the characteristics of our observation seems to our models match, it could be a cloud of hydrogen.

This is the good part of the story.But the bitterly hard part remains,the simulation of this effect and then observation of a known cluster and after that data reduction in order to find the best candidate stars which their light curves shows the effect of scintillation is Farhangs hard task.

6+1 lesson from f(R)-gravity

Last Monday 3 of November a nice talk-article was appeared in arXiv with the title of:

6+1 lessons from f(R) gravity with the arxiv address arXiv:0810.5594

In this article Thomas P. Sotiriou a postdoc in Meryland, describe the 7 lessons that we learn from studing the straightforward form of modification of gravity.

Thomas P. Sotiriou received his Ph.D. in SISSA in September 2007 under supervision of Stefano Liberati and John Miller with the title of Modified Actions for Gravity: Theory and Phenomenology with the address of arXiv:0710.4438 .

He is the great expert of modified gravity.Tracking his articles in recent years help me lot even in preparing my Master thesis.

Homepage of Thomas Sotiriou

http://terpconnect.umd.edu/~sotiriou/mysite/About_Me.html