我們發展出了一套基於測光系統的方法，用來分離出一種相對低質量但活躍於恆星誕生的星系在紅移$\le$1.5的天區範圍內。我們將此方法運用在英國紅外望遠鏡(United Kingdom InfraRed Telescope, UKIRT)的紅外深度觀測(UKIDSS-Ultra Deep Survey)，加法夏望遠鏡(Canada-France-Hawaii Telescope, CFHT)的勘測(Legacy Survey)以及宇宙學演化觀測(COSMOlogical evolution Survey, COSMOS)中的多波段探測資料(Ultra Visible and Infrared Survey Telescope for Astronomy- UltraVISTA)。

我們也結合了各個多波段探測的光譜觀測資料，得到了這類型星系的細微特徵。這類型的星系具有相對低的恆星質量 (stellar mass, M$_{*}$$\sim$10$^{9}$M$_{\bigodot}$)，低金屬豐度 (metallicity, 12+log(O/H)$\sim$8.0)；但擁有高的絕對恆星誕生率(specific star formation rate, SSFR$\sim$10$^{-9}$M$_{\bigodot}$yr$^{-1}$/M$_{\bigodot}$)。

這類型的星系也相似於靠近我們的藍色致密矮星系(Blue Compact Dwarfs, BCDs)，在紅移$\sim$0.8的低元素豐度但是具有強恆星誕生的星系(luminous metal-poor star forming galaxies)以及為在高紅移的萊曼$\alpha$發射體 (Ly$\alpha$ Emitters, LAEs)。

We have recently developed a method based on broad-band photometry to isolate a sample of galaxies with relatively low stellar mass but extremely active star-formation at redshift up to z$\sim$1.5. We extend our method to select those galaxies from several deep photometry archive datasets which are the UKIRT infrared deep sky survey - Ultra Deep Survey (UKIDSS-UDS), Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) and COSMOS-UltraVISTA survey.

The spectroscopic data for each of the catalogs give us a good chance to look at the properties of our samples. These galaxies have low stellar mass (M$_{*}$$\sim$10$^{9}$M$_{\bigodot}$) and low metallicity (12+log(O/H)$\sim$8.0); however, they display high star formation rate per stellar mass (SSFR$\sim$10$^{-9}$M$_{\bigodot}$yr$^{-1}$/M$_{\bigodot}$). Interaction-induced infall of gas could be consistent with these galaxies that high specific star formation rates. These galxies may allow to study in great detail processes, such as starburst activity and chemical enrichment, which are common in the early universe.

The properties of low metallicity for these galaxies are similar with Blue Compact Dwarfs (BCDs) in the local Universe, luminous metal-poor star forming galaxies at intermediate redshifts at z$\sim$0.8 and Ly$\alpha$ Emitters (LAEs) at high redshifts. We will discuss more details about our photometic selection and the properties of these young galaxies.

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