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تسجيل مستخدم جديدA Faint Flux-Limited Lyman Alpha Emitter Sample at $zsim0.3$
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We present a flux-limited sample of $zsim0.3$ Ly$alpha$ emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism spectroscopic data. The published GALEX $zsim0.3$ LAE sample is pre-selected from continuum-bright objects and thus is biased against high equivalent width (EW) LAEs. We remove this continuum pre-selection and compute the EW distribution and the luminosity function of the Ly$alpha$ emission line directly from our sample. We examine the evolution of these quantities from $zsim0.3$ to $2.2$ and find that the EW distribution shows little evidence for evolution over this redshift range. As shown by previous studies, the Ly$alpha$ luminosity density from star-forming galaxies declines rapidly with declining redshift. However, we find that the decline in Ly$alpha$ luminosity density from $z=2.2$ to $z=0.3$ may simply mirror the decline seen in the H$alpha$ luminosity density from $z=2.2$ to $z=0.4$, implying little change in the volumetric Ly$alpha$ escape fraction. Finally, we show that the observed Ly$alpha$ luminosity density from AGNs is comparable to the observed Ly$alpha$ luminosity density from star-forming galaxies at $z=0.3$. We suggest that this significant contribution from AGNs to the total observed Ly$alpha$ luminosity density persists out to $zsim2.2$.
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