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The Subaru Seminar is
usually held in Room 104 of the Hilo Base Facility, adjacent
to the main lobby. Everyone is welcome to attend. If you are
interested in giving a seminar, please contact Subaru seminar organizers
(Tadayuki Kodama, Naoyuki Tamura, Tomonori Usuda)
by email : sseminar_at_subaru.naoj.org (please change"_at_" to @).
April 11, Wednesday, at 11:00 am
" New Results on the Properties of z=0.5-2.2 Emission-line Galaxies: Dust
Attenuation, Stellar Population, and the H-alph LFs "
Chun Ly
(Space Telescope Science Institute, USA)
Since the star formation rate (SFR) density of galaxies is an order of
magnitude higher at high redshift than in the local universe, emission-line
galaxies are prominent at earlier cosmic time, and thus are useful
probes of the evolution of galaxies. Current techniques to identify
the emission-line galaxy population include grism surveys, slit
spectroscopy,
and narrow-band imaging. I will focus on the properties of emission-line
galaxies selected through narrow-band imaging, drawing on two different
surveys, the Subaru Deep Field (SDF) and the NewH-alpha Surveys.
First, I will discuss results on the dust attenuation of 400 H-alpha
selected galaxies at z=0.4 and z=0.5 from the SDF. I will present the
highest redshift Balmer decrement measurements for 60 individual galaxies,
revealing a correlation of dust attenuation with stellar mass and H-alpha
luminosity. I will also show that the dust attenuation corrections derived
from modeling the rest-frame 1000 Angstrom to 1.6 microns SEDs, which
are correlated with the individual Balmer measurements, are reliable.
With reliable constraints, we determine that two-thirds of star formation
is obscured at z~0.5.
Second, I will then use our unique samples of z~1.5--1.6 [OII] emitting
galaxies identified in the SDF to study the stellar population of high-z
galaxies selected through narrow-band imaging. The [OII]-selected population
spans a diverse population of star-forming galaxies with typical stellar
ages of 300 Myrs and stellar masses of 3 X 10^9 Msun. We have also compared
our sample against common techniques (i.e., "BX/BM" and BzK) to select
high-z galaxies, and find that the narrow-band selection simultaneously
spans
both populations. This strongly indicates that selection biases present
in the narrow-band samples are minimal compared to popular color selections.
Finally, I will describe the NewH-alpha Survey, which uses near-infrared
narrow-band imaging from NOAO/CTIO's NEWFIRM and Magellan's FourStar
to extend the H-alpha luminosity functions (LFs) to z=0.81 and z=2.2.
These LFs are the most reliably constrained with (1) significant
spectroscopic confirmation for the lower redshift sample, and (2)
the use of a second narrow-band filter to detect [OII] emission for
>80% of our z=2.2 H-alpha emitters, thus providing a highly confirmed
z=2.2 sample. With these LFs, I will discuss constraints on the
faint-end slope of the H-alpha LF and the H-alpha SFR densities
at these redshifts.
Seminars are also held at JAC,
CFHT,
and IfA.
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