[seminar] Astro Journal Club on 18 November

[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 a faint quasar seen at the end of the reionization era.

Presenter: Mladen Novak
Paper title: Discovery of a Faint Quasar at z ~ 6 and Implications for
Cosmic Reionization
Authors: Kim, Y., Im, M., Jeon, Y., et al.

Summary:
Recent studies suggest that faint active galactic nuclei may be
responsible for the reionization of the universe. Confirmation of this
scenario requires spectroscopic identification of faint quasars (M1450 >
-24 mag) at z > 6, but only a very small number of such quasars have been
spectroscopically identified so far. Here, we report the discovery of a
faint quasar IMS J220417.92+011144.8 at z ~ 6 in a 12.5 deg2 region of the
SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the
quasar shows a sharp break at ~8443 angstroms with emission lines
redshifted to z = 5.944 +/- 0.002 and rest-frame ultraviolet continuum
magnitude M1450 = -23.59 +/- 0.10 AB mag. The discovery of IMS
J220417.92+011144.8 is consistent with the expected number of quasars at z
~ 6 estimated from quasar luminosity functions based on previous
observations of spectroscopically identified low-luminosity quasars. This
suggests that the number of M1450 ~ -23 mag quasars at z ~ 6 may not be
high enough to fully account for the reionization of the universe. In
addition, our study demonstrates that faint quasars in the early universe
can be identified effectively with a moderately wide and deep
near-infrared survey such as the IMS.

Link to the paper:
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1511.01585

Hope to see you all on Wednesday!

Note: The 25 November and 2 December slots are already taken, but the
remaining December slots are still free if you are interested in
presenting a paper.

Cheers,
Oskari