[seminar] Astro Journal Club on May 10th

[Lana Ceraj]

Dear all, 

Astro Journal club continues this Wednesday at 3 p.m. (sharp) in the seminar room F-201 of the Physics Department. 

Presenter: Eleni Vardoulaki, dr. sc.

Title of talk: FR-type radio sources in COSMOS

Abstract: 
Modern radio interferometric surveys, due to improved receiver and correlator capabilities provide higher sensitivity and higher resolution data than past radio surveys, thus revealing a huge variety of radio structures down to uJy levels. Here we present an analysis on the radio structure of 350 radio sources from the VLA-COSMOS 3GHz Large Project (JVLA-COSMOS; Smolcic et al. 2017), reaching a resolution of 0.75’’ with sensitivity of ~2.3uJy/beam. These objects were selected on the basis of their extended radio structure and were placed, by visual inspection, in radio classes that follow the FR-type classification of Fanaroff & Riley (1974); approximately half of them are associated with active galactic nuclei (AGN).  The purpose of this project is to compare the radio structure of radio AGN to their energetics (e.g. accretion properties) and environment (e.g. X-ray groups in COSMOS, George et al. 2010), and relate these to the different observed FR radio structures to understand the physical mechanisms behind the FRI/FRII dichotomy. We report the discovery of low radio power (log(L3GHz/W/Hz/sr)~22), small scale (~30 kpc) classical-double radio sources (FRII) at redshifts z ~ 1, which we are able to resolve due to the unprecedented resolution of 0.75 arcsec (FWHM) of JVLA-COSMOS. Furthermore, our results agree with the scenario that FRII sources are in-falling: at redshifts z > 1 FRIIs can be located at the outskirts of the associated X-ray group, but at low redshifts they sit at the centre of the potential well. Finally, we present preliminary results on an automatic (semi-supervised) machine-learning method to classify radio sources with complex radio structures, and discuss the necessity for automatic methods in identifying and classifying radio sources in large, current and future, radio surveys.
 
If you have recently read interesting astrophysics paper you would like to present, please contact me via e-mail: lceraj at phy.hr <mailto:lceraj at phy.hr>

See you on Wednesday.

Cheers,
Lana

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