[seminar] Astro Journal Club on 13 May

[Oskari Miettinen]

Dear all,

The Astro Journal Club will be held on Wednesday at 10:15 in the seminar
room F-201 of the Physics Department. This time we will discuss about the
very high-redshift Lyman break galaxy EGS-zs8-1.

Presenter: Nikola Baran
Paper title: A Spectroscopic Redshift Measurement for a Luminous Lyman
Break Galaxy at z=7.730 using Keck/MOSFIRE
Authors: Oesch, P. A., van Dokkum, P. G., Illingworth, G. D., et al.

Summary:
We present a spectroscopic redshift measurement of a very bright Lyman
break galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was
pre-selected photometrically in the EGS field as a robust z~8 candidate
with H=25.0 mag based on optical non-detections and a very red
Spitzer/IRAC [3.6]-[4.5] broad-band color driven by high equivalent width
[OIII]+Hbeta line emission. The Lyalpha line is reliably detected at 6.1
sigma and shows an asymmetric profile as expected for a galaxy embedded in
a relatively neutral inter-galactic medium near the Planck peak of cosmic
reionization. The line has a rest-frame equivalent width of EW0=21+-4 A
and is extended with V_FWHM=360+90-70 km/s. The source is perhaps the
brightest and most massive z~8 Lyman break galaxy in the full CANDELS and
BoRG/HIPPIES surveys, having assembled already 10^(9.9+-0.2) M_sol of
stars at only 650 Myr after the Big Bang. The spectroscopic redshift
measurement sets a new redshift record for galaxies. This enables reliable
constraints on the stellar mass, star-formation rate, formation epoch, as
well as combined [OIII]+Hbeta line equivalent widths. The redshift
confirms that the IRAC [4.5] photometry is very likely dominated by line
emission with EW0(OIII+Hbeta)= 720-150+180 A. This detection thus adds to
the evidence that extreme rest-frame optical emission lines are a
ubiquitous feature of early galaxies promising very efficient
spectroscopic follow-up in the future with infrared spectroscopy using
JWST and, later, ELTs.

Link to the paper: http://adsabs.harvard.edu/abs/2015arXiv150205399O

Hope to see you all on Wednesday!

Cheers,
Oskari