[Emeriti-faculty] Department of Physics and Astronomy Events for Week of February 1, 2010 through February 5, 2010

[Gayle Grant <gayle grant tufts edu>]

Events for this week:

Monday
February 1, 2010
Physics Graduate Students’ JOURNAL CLUB
Tracy McAskill
“Protons and Generalized Parton distributions”
Monday, February 1, 2010
Robinson Hall 250, 5:00 pm
(undergraduate students, faculty and anyone interested are also invited: 
food served at 4:30 pm in Knipp Library)


Friday, February 5, 2010
Noon
Robinson 251
Informal lunch (Pizza) with Dr. Ezequiel Treister
Graduate and Undergraduate Students should attend.

3:00 pm
Friday, February 5, 2010
Nelson Auditorium, Anderson Hall
TUFTS UNIVERSITY
Special Physics and Astronomy Colloquium
“Heavily Obscured Supermassive Black Holes”
Ezequiel Treister
University of Hawaii
Abstract:
We constrain the number density and evolution of heavily-obscured Active 
Galactic Nuclei (AGN). In the local Universe we use the wide area 
surveys from the Swift and INTEGRAL satellites, while for high redshifts 
we explore candidate selections based on a combination of X-ray and 
mid-IR parameters. To find obscured AGN at high redshifts, z~2, we study 
the properties of a sample of objects selected based on their very high 
mid-IR to optical flux ratios. We present significant evidence 
supporting the AGN nature of a large fraction of these sources, 
including a strong stacked X-ray signal. Using this sample we measured 
the space density of heavily-obscured AGN at z~2, finding a strong 
evolution in the number of high-luminosity sources from z=1.5 to 2.5. 
Such strong evolution was not predicted by any existing AGN luminosity 
function, but can be accurately explained by a simple prescription in 
which every new quasar is generated by a major merger of two gas-rich 
massive galaxies, which is originally heavily obscured and after ~100 
Myrs removes most of the surrounding gas and dust to reveal an 
unobscured quasar.

Nelson Auditorium
Refreshments served in Robinson Hall, Room 251 at 2:30 pm