Subaru Seminars



This Month






Site Map

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 : (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.

Copyright (c) 1999-2000 Subaru Telescope, NAOJ. All rights reserved.