Properties of $zsim3-6$ Lyman Break Galaxies. II. Impact of nebular emission at high redshift

Дата и время публикации : 2012-07-16T13:04:48Z

Авторы публикации и институты :
S. de Barros
D. Schaerer
D. P. Stark

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 33 pages, 30 figures, 5 tables, extended version addressing referee comments, conclusions unchanged, accepted for publication in A&A
Первичная категория: astro-ph.CO

Все категории : astro-ph.CO

Краткий обзор статьи: We present a homogeneous, detailed analysis of the spectral energy distribution (SED) of $sim$ 1700 LBGs from the GOODS-MUSIC catalog with deep multi-wavelength photometry from $U$ band to 8 $mu$m, to determine stellar mass, age, dust attenuation and star formation rate. Using our SED fitting tool, which takes into account nebular emission, we explore a wide parameter space. We also explore a set of different star formation histories. Nebular emission is found to significantly affect the determination of the physical parameters for the majority of $z sim $ 3–6 LBGs. We identify two populations of galaxies by determining the importance of the contribution of emission lines to broad-band fluxes. We find that $sim65$% of LBGs show detectable signs of emission lines, whereas $sim35$% show weak or no emission lines. This distribution is found over the entire redshift range. We interpret these groups as actively star forming and more quiescent LBGs respectively. We find that to reproduce some colors affected by strong emission lines, it is necessary to considerer SED fits with very young ages ($<50$ Myr). Other arguments favoring episodic star formation and relatively short star formation timescales are also discussed. Taking into account nebular emission generally leads, for a given SFH, to a younger age, lower stellar mass, higher dust attenuation, and higher star formation rate, although with increased uncertainties. We find a trend of increasing dust attenuation with galaxy mass, and a large scatter in the SFR-$M_{star}$ relation. Our analysis yields a trend of increasing specific star formation rate with redshift, as predicted by recent galaxy evolution models. The physical parameters of approximately two thirds of high redshift galaxies are significantly modified when nebular emission is taken into account. [abridged]

Category: Physics