Monday Seminar for the year 2009

The talks are shown in order of increasing time.

 

 

 

 

Date

 

 

Speaker

Topic

12

Jan

 

Xun Shi

Nulling of 3-point Intrinsic-Shear Alignment

26

Jan

 

Elena Cenacchi

Full Stokes Polarimetry with the Effelsberg Radio telescope

9

Feb

 

Seungkyung Oh

Dynamical Ejections of Massive Stars from Young Star Clusters

23

Feb

 

Carnival Monday

 

9

Mar

 

Chin-Shin Chang

15 GHz VLBI detection of the HST-1 feature in the M87 jet

23

Mar

 

Felipe Navarrete

The Stacking technique in the MAMBO field

6

Apr

 

Laura Gómez González

Physical and Chemical Properties of Infrared Dark Cloud Clumps

20

Apr

 

Xinzhong Er

Mass reconstruction by gravitational lensing

4

May

 

No Seminar

 

18

May

 

Devaky Kunneriath

mm/NIR emission from Sgr A*

1

Jun

 

Whit Monday

 

15

Jun

 

Gabriele Surcis

The magnetic field during the high-mass protostellar phase. The case of W75N

29

Jun

 

Das Koyel

Conversion from linear to circular polarization and Stokes Parameters in FPGA

13

Jul

 

Summer Break

 

27

Jul

 

Summer Break

 

10

Aug

 

Rusen Lu

High resolution inter-day VLBI monitoring of Sagittarius A*

24

Aug

 

Frank Schinzel

Long-term kinematics of the parsec-scale jet in 3C 345

31

Aug

*

Mar Mezcua

Black Hole Masses and Luminosities in X-shaped radio sources

7

Sep

 

Filomena Volino

Global VLBI observations of the gravitational lens MG0414: constraints for mass reconstruction

21

Sep

 

Kirill Sokolovskyi

Constraining the magnetic field in blazar jets by multifrequency VLBI observations

5

Oct

 

Arturo Gomez

Molecular Outflows in star-forming regions

19

Oct

 

Ioannis Nestoras

Cm to Sub-mm monitoring of gamma-ray blazars in the #Fermi-GST era. The F-Gamma Project

chair: A. Gomez

Abstract:

The blazars, being the most dramatic manifestations of of the activity sustained by a supermassive black hole in galactic nuclei, show several exotic characteristics such as intense variability at almost all energy bands, highly super-luminal apparent motions, high brightness temperatures. Most of these characteristics are attributed to very small angles between the line-of-sight and the jet axis. The Fermi-GST (previously GLAST) is a space mission studying the cosmos in the gamma-ray energy band. Large Area Telescope (LAT) on-board Fermi-GST has area, angular resolution and field-of-view superior to that of its predecessors between 20 MeV and 300 GeV. However, only when combined with other energy bands the outcome of studies is maximized provided the broad-band character of the blazar emission. The Fermi-GST AGN Multi-frequency Monitoring Alliance known as F-GAMMA project is a program for the monthly monitoring of the spectra of ~60 Fermi-GST blazars from cm to sub-mm bands as well as optical and IR. The Effelsberg 100 m telescope is pivoting the program together with the 30m IRAM telescope as well as the APEX 12 m antenna covering roughly from 2 GHz up to 350 GHz with precision of a few percent. Here we present first results including light curves, spectra and variability properties, including a first comparison with their gamma-ray properties as observed recently by Fermi-GST.

2

Nov

 

Esteban Morales

Triggered Star Formation in the IR Bubble G10.31-00.15

chair: I. Nestoras

Abstract:

In the last years, many new young embedded stars clusters have been discovered in the IR (mainly using 2MASS). In this project, our aim is to study the molecular environment of them, searching for physical associations in submm continuum emission (ATLASGAL, survey at 870 microns with APEX-LABOCA), which traces the cold dust, and observing a subsample of objects in CO isotopes to probe the dynamical evolution and kinematics of the cluster’s surrounding molecular gas. Since young star clusters represent an ideal scenario to study the interaction of recently formed massive stars with the surrounding interstellar medium, we have identified in many objects of our sample the potential presence of triggered formation, as shown by clear ring structures

seen in the mid-IR (the so called "IR bubbles") and nicely correlated with ATLASGAL emission. After giving a general description of our project, I will focus in the source G10.31-00.15 and show how the velocity field of the CO emission is consistent with an expanding gas shell, using uniquely geometrical arguments.

16

Nov

 

Jasmin Vural

Revealing the inner disk structure of the T Tauri star S CrA N with infrared interferometry

chair: E. Morales

Abstract:

We probed the circumstellar disk of the T Tauri star S CrA N with spectro-interferometry using VLTI/AMBER and VLTI/MIDI. We applied a temperature gradient model to both visibility and SED and found an almost face-on disk consisting of two components as best match to the

data. The outer component is a disk which extends from approximately 0.65 AU to 25 AU. The inner component has a radius of approximately 0.15 AU. Our finding is consistent with the existence of a puffed-up inner rim which is located at the dust sublimation radius.

30

Nov

 

Mohammad Zamaninasab

Near Infrared Flares of Sagittarius A*: Importance of Near Infrared Polarimetry

chair: J. Vural

Abstract:

We used a sample of NIR flares of Sgr A* observed in the polarimetry mode to study the nature of the observed quasi-periodic oscillations. Using the z-transformed discrete correlation function algorithm, we found a significant correlation between changes in the measured polarimetric data and total flux densities. This provides evidence that the variations probably do not originate from random changes in the accretion parameters. In order to constrain the physical properties of the emitting region we employed a relativistic disk model with an azimuthal over-density of relativistic electrons. A combination of a synchrotron mechanism and relativistic amplifications allows us to fit the real observed data, and make predictions about astrometric parameters of the accretion disk around Sgr A*. The modelled light curves show the same close to zero time-lag correlation between the flux and polarimetric data as has been deduced from observations. The model enables us to constrain the expected direction of the collimated outflow from Sgr A*. The effects of gravitational shearing, fast synchrotron cooling of the components and confusion from a variable torus have been taken into account. Simulated centroids of NIR images lead us to the conclusion that any clear observation of position wander of the centre of NIR images with future infrared interferometers will strongly prove the existence of orbiting hot spots in the vicinity of our Galactic super-massive black hole.

14

Dec

 

Evangelia Tremou

Low Luminosity Quasi Stellar Objects

chair: M. Zamaninasab

Abstract:

I am going to present a preliminary analysis of a volume-limited sample of nearby galaxies hosting low-luminosity quasi-stellar objects (LLQSOs). The sample has been drawn from the Hamburg/ESO QSO survey (Wisotzki+2000), which has a well-defined flux limit of B_J<17.3. Our only selection criterion for the QSOs was their small cosmological distance: only objects with a redshift z<0.060 were chosen. This redshift was selected to ensure the presence of the CO (2-0) band head in the near-infrared (NIR) K -band. With this criterion we end up with a sample of 99 LLQSOs, with absolute visible magnitudes just below the classical Seyfert / QSO demarcation. Specifically, an optical spectroscopic study of the sample has been carrying out in order to characterize the excitation degree of the sample and distinguish between possible LINER and Seyfert activity. The aim of the present project is the characterization of the LLQSOs of the sample. I have been carrying out an optical spectroscopic study of the sample, and compare the results with those of studies in different bands.

 
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