Modeling the Cirrus Clouds



Abstract:



The cirrus clouds are mainly diffuse or translucent clouds, with typically

a very low visual extinction. But such clouds may have dense molecular cores.

These cores could be precursors to star formation and are very good candidates

to study early phases of stellar evolution. Despite of the apparent simplicity of

these regions, the observations of the dense gas tracers contradict with the

models and hence suggesting a gap in our understanding of these regions.

Polaris Flare is a high latitude cirrus cloud, with several star-less cores. A

translucent molecular cloud MCLD 123.5+24.9 is one of the denser regions of

the Polaris cirrus complex, located in the direction near the celestial North Pole.

I am going to discuss the models of this region using Cloudy with the help of

CO transition line observations and recent Herschel observations from the

continuum dust emission.

Quasar Spectral Energy Distributions and the Effects of Intervening Clouds



Abstract:



The nature of the Broad Line Region (BLR) of Active Galactic Nuclei (AGN) is an area of

vigorous debate. The geometry of the BLR clouds is also uncertain. I will first present

the current model of AGNs and BLR. Then I will review recent work on the X-ray time

variability of Mrk 766, a Seyfert 1 galaxy.  I will then introduce a new geometry for

the BLR clouds. This new geometry, which we call the intervening BLR clouds model,

has BLR clouds along our line of sight. These intervening clouds generate a depression

at ~900Å to ~1200Å. Observations of Mrk 766 and other AGNs suggest that intervening

clouds may exist in most AGNs. The real SED of the AGNs in that wavelength range may

be higher than we now suppose due to the depression made by intervening clouds.

Magnetic fields in the High Velocity Clouds



Abstract:

The high velocity clouds (HVCs) that cover the sky around the Milky Way are now

widely believed to be low-metallicity gas that is being accreted by the Galaxy,

fueling star formation and stabilizing the Galactic disk. There is a fundamental

question about what holds the clouds together as coherent entities. One possible

mechanism for stabilizing a cloud is its magnetic field.  Indeed, the interaction of a falling

cloud with the galactic halo depends keenly on the strength and orientation of the

magnetic field. Smith's Cloud is one of those falling clouds that is on its way to

interact with the galactic plane. I'll talk about its current observational result while

trying to remove the possible instrumental effects.

Manipulating surface properties with purpose: from ferroelectric dipoles to plasmonic resonances

From Bose-metals of frustrated spins and bosons to non-Fermi-liquids of electrons

Topological Phases in One Dimension