[seminar] Astro Journal Club on 21 October

[Oskari Miettinen]

Dear all,

Our Astro Journal Club will be held on Wednesday at 3:00 pm (sharp) in the
seminar room F-201 of the Physics Department. This time we will discuss
about hot DOGs.

Presenter: Oskari Miettinen
Paper title: Four hot DOGs in the microwave
Authors: Frey, S., Paragi, Z., Gabanyi, K. E, and An, T.

Summary:
Hot dust-obscured galaxies (hot DOGs) are a rare class of hyperluminous
infrared galaxies identified with the Wide-field Infrared Survey Explorer
(WISE) satellite. The majority of them is at high redshifts (z~2-3), at
the peak epoch of star formation in the Universe. Infrared, optical,
radio, and X-ray data suggest that hot DOGs contain heavily obscured,
extremely luminous active galactic nuclei (AGN). This class may represent
a short phase in the life of the galaxies, signifying the transition from
starburst- to AGN-dominated phases. Hot DOGs are typically radio-quiet,
but some of them show mJy-level emission in the radio (microwave) band. We
observed four hot DOGs using the technique of very long baseline
interferometry (VLBI). The 1.7-GHz observations with the European VLBI
Network (EVN) revealed weak radio features in all sources. The radio is
free from dust obscuration and, at such high redshifts, VLBI is sensitive
only to compact structures that are characteristic of AGN activity. In two
cases (WISE J0757+5113, WISE J1603+2745), the flux density of the
VLBI-detected components is much smaller than the total flux density,
suggesting that ~70-90 per cent of the radio emission, while still
dominated by AGN, originates from angular scales larger than probed by the
EVN. The source WISE J1146+4129 appears a candidate compact symmetric
object, and WISE J1814+3412 shows a 5.1-kpc double structure, reminiscent
of hot spots in a medium-sized symmetric object. Our observations support
that AGN residing in hot DOGs may be genuine young radio sources where
starburst and AGN activities coexist.

Link to the paper: http://adsabs.harvard.edu/abs/2015arXiv151004179F

Hope to see you all on Wednesday!

Just to remind you that our Skype ID is astrozg, and the presentation
repository is available at http://zgal.phy.hr/ajc/

Cheers,
Oskari