[seminar] Astro Journal Club on 17 Dec

[Oskari Miettinen]

Dear all,

Our Astro Journal Club will be held again on Wednesday at 10:15 in the
seminar room F-201 of the Physics Department. This time we will discuss
about the recent ALMA observations towards the high-redshift sub
millimetre galaxy AzTEC3.

Presenter: Neven Tomicic
Paper title: ALMA Imaging of Gas and Dust in a Galaxy Protocluster at
Redshift 5.3: [C II] Emission in "Typical" Galaxies and Dusty Starbursts
about 1 Billion Years after the Big Bang
Authors: Riechers, D. A., Carilli, C. L., Capak, P. L., et al.

Abstract:
We report interferometric imaging of [C II](2 P 3/2-2 P 1/2) and OH(2Pi1/2
J = 3/2-1/2) emission toward the center of the galaxy protocluster
associated with the z = 5.3 submillimeter galaxy (SMG) AzTEC-3, using the
Atacama Large (sub)Millimeter Array (ALMA). We detect strong [C II], OH,
and rest-frame 157.7 micron continuum emission toward the SMG. The [C
II](2 P 3/2-2 P 1/2) emission is distributed over a scale of 3.9 kpc,
implying a dynamical mass of 9.7e10 Msun, and a star formation rate (SFR)
surface density of SigmaSFR = 530 Msun yr-1 kpc-2. This suggests that
AzTEC-3 forms stars at SigmaSFR approaching the Eddington limit for
radiation pressure supported disks. We find that the OH emission is
slightly blueshifted relative to the [C II] line, which may indicate a
molecular outflow associated with the peak phase of the starburst. We also
detect and dynamically resolve [C II](2 P 3/2-2 P 1/2) emission over a
scale of 7.5 kpc toward a triplet of Lyman-break galaxies with moderate
UV-based SFRs in the protocluster at about 95 kpc projected distance from
the SMG. These galaxies are not detected in the continuum, suggesting
far-infrared SFRs of <18-54 Msun yr-1, consistent with a UV-based estimate
of 22 Msun yr-1. The spectral energy distribution of these galaxies is
inconsistent with nearby spiral and starburst galaxies, but resembles
those of dwarf galaxies. This is consistent with expectations for young
starbursts without significant older stellar populations. This suggests
that these galaxies are significantly metal-enriched, but not heavily
dust-obscured, "normal" star-forming galaxies at z > 5, showing that ALMA
can detect the interstellar medium in "typical" galaxies in the very early
universe.

Link to the paper: http://adsabs.harvard.edu/abs/2014ApJ...796...84R

Hope to see you all on Wednesday!

Best regards,
Oskari Miettinen