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 "
(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
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
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,