Monday Seminar for the year 2017

The presentations are shown in order of increasing time.

2-Jan-2017

 

 

9-Jan-2017

 

 

16-Jan-2017

 

Monthly Discussion Room 002

23-Jan-2017

 

Natalya Porayko (2)

chair: Ann Kathrin Baczko

Measuring RM variations with LOFAR: ISM vs ionosphere

Magnetic fields play a crucial role in the magneto-hydrodynamic (MHD) heating of the interstellar medium (ISM) and the density fragmentation of cold molecular clouds, thus regulating the process of star formation. They are also known to be important in particle ray acceleration, which can provide the pressure to drive galactic outflows. However, many important characteristics of the magnetic fields, such as their origin and evolution, strength and structure, and their influence on Galactic dynamics remain unknown. Using the data from highly polarized pulsars observed with German LOFAR stations, we will investigate long-term Rotation Measure (RM) variations. Our goal is to update our knowledge about the small-scale turbulent structure of the magnetic fields and the electron density in the ISM of our Galaxy. These variations arise as the pulsar moves along the tangent plane and, thus, the pulsar beam intersects different parts of the ISM. Besides being sensitive to the ISM effects due to LOFAR low-frequency range, our data are also susceptible to ionospheric effects that are undesirable for our investigation. Using long pulsars' observations we can carefully investigate accuracy of the GPS ionospheric maps and independently estimate parameters of the noise, generated by imperfect ionospheric modeling. After careful subtraction of ionospheric contribution the residual RM data is expected to show the presence of red noise, whose parameters will depend on the regime of ISM turbulence.

30-Jan-2017

 

 Won Ju Kim (3)

chair: N. Porayko

Millimeter hydrogen radio recombination lines from HII regions in molecular clumps

I would like to mainly present millimeter hydrogen radio recombination line surveys with IRAM and Mopra telescopes,
and then shortly to show preliminary results from submillimeter hydrogen RRL surveys with APEX telescope.

We carried out millimeter radio recombination lines (mm-RRLs, 39 ≤ n ≤ 65 and ∆n = 1, 2, 3, and 4) surveys using the IRAM 30m and MOPRA 22m telescopes toward 976 compact dust clumps of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) survey.
The (sub)millimeter RRLs can be used to derive physical propoerties of HII regions and to provide velocity information of ionized gas.
Therefore, these mm-RRLs surveys aim at searching for embedded HII regions in the dust clumps and studying the characteristics of the HII regions. The targeted dust clumps were an unbiased sample without any specific criteria and half of the sample were also selected to be mid infrared dark to cover very young clumps.
We detected mm-RRLs toward 178 HII regions; 178 Hnα, 65 Hnβ, 23 Hnγ, and 22 Hnδ mm-RRLs were detected. It is the largest sample of mm-RRLs to date. All sources were searched subsequently for radio continuum source and mid infrared source counterparts. There are eight clumps having potential HII regions based on only mm-RRL detections. Nine clumps have broad RRL features (FWHM > 40 km/s). Such broad recombination line objects (BRLOs) imply the existence of significant turbulent motions. Except for detecting the BRLOs, we also found an evidence that the dynamics of the mm-RRLs are related to turbulent motions in the parental molecular clouds to compare to their H13CO+(1-0) FWHM linewidths with detection (a mean linewidth of 4.18 km/s) and non-detection (a mean linewidth of 3.08 km/s) of mm-RRLs.
We present a significant correlation (correlation coefficient, 0.72 and slope, 0.86) between integrated fluxes of mm-RRL and 6 cm continuum
emission. The good correlation shows that the mm-RRLs trace the radio continuum sources detected by high-resolution observations. By calculating the electron densities we find the mm-RRL emission is associated with HII regions with electron density < 10^5 cm^-3 and HII region diameter > 0.03 pc.

 

 

 

6-Feb-2017

 

Monthly Discussion

13-Feb-2017

 

 Henning Hilmarsson (1) & Vivien Thiel (2)

20-Feb-2017

 

 Andrew Cameron (3)

chair: V. Thiel

The Most Relativistic Binary Pulsar, and other news from the HTRU-S LowLat Pulsar Survey

Pulsars, rapidly-rotating highly-magnetised neutron stars, can serve as fantastic natural laboratories for testing theories of gravity when discovered as part of binary systems. The most prominent example of such a binary has been the Double Pulsar, PSR J0737-3039A/B, which has been used to test General Relativity to within uncertainties of just 0.05%. The HTRU-South Low Latitude pulsar survey represents the most sensitive blind pulsar survey taken of the southern Galactic plane to date, and has resulted in the discovery of 104 additional pulsars thus far. With long integration times and a custom acceleration search pipeline, one of the primary aims of this survey has been to discover new relativistic binary pulsars which may be able to produce even stronger tests of gravity theories. Here I will present our binary pulsar searching strategy and report on the discovery highlight of the survey, a new relativistic binary pulsar. With a short orbital period of 4.4 hours and an eccentricity of 0.606, this double neutron star system represents the most relativistic binary pulsar discovered in our Galaxy to date, and has potential to exceed the tests set down and by the Double Pulsar and place new limits on gravitational theories such as General Relativity.

27-Feb-2017

 

Rosenmontag

 

 

 

6-Mar-2017

 

Monthly Discussion

13-Mar-2017

 

 Marilyn Cruces (1) & Yuxin Lin (1)

20-Mar-2017

 

 Michal Zajacek (3) Kevin Harrison (1)

27-Mar-2017

 

 Michael Mattern (3) & Mélisse Bonfond (2)

 

 

 

3-April-2017

 

Monthly Discussion

10-April-2017

 

 Fateme Kamali (3) & Madhuri Gaidwad (1)

17-April-2017

 

Easter Monday

24-April-2017

 

 Anna Mikler (3) & Chaoli Zhang (1)

 

 

 

1-May-2017

 

May Holiday

8-May-2017

 

Monthly Discussion

15-May-2017

 

Jackie Ma (2) & Weiwei Chen (1)

22-May-2017

 

 Efthalia Traianou (1)

29-May-2017

 

 Jae-Young Kim (2) & Elaheh Hosseini (2)

 

 

 

5-June-2017

 

Pfingstmontag

12-June-2017

 

Monthly Discussion

19-June-2017

 

 

26-June-2017

 

 

 

 

 

3-Jul-2017

 

Monthly Discussion

10-Jul-2017

 

 

17-Jul-2017

 

 

24-Jul-2017

 

 Marzieh Parsa (3)

31-Jul-2017

 

 Jens Erler (3)

 

 

 

7-Aug-2017

 

Monthly Discussion

14-Aug-2017

 

  Joey Martinez (3)

21-Aug-2017

 

28-Aug-2017

 

Henning Hilmarsson (2)

 

 

4-Sept-2017

 

Monthly Discussion

11-Sept-2017

 

 

18-Sept-2017

 

 Maja Kierdof (3)

25-Sept-2017

 

 

 

 

 

2-Oct-2017

 

Monthly Discussion

9-Oct-2017

 

 

16-Oct-2017

 

 

23-Oct-2017

 

30-Oct-2017

 

 Sandra Unruh (3)

 

 

 

6-Nov-2017

 

Monthly Discussion

13-Nov-2017

 

 

20-Nov-2017

 

 

27-Nov-2017

 

 

 

 

 

4-Dec-2017

 

Monthly Discussion

11-Dec-2017

 

 

18-Dec-2017

 

 

25-Dec-2017

 

Christmas

 
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