PRIMUS：在紧密星系对中增强的特定恒星形成率
PRIMUS: Enhanced Specific Star Formation Rates In Close Galaxy Pairs
摘要：
星系之间的潮汐相互作用可以触发恒星形成，这有助于宇宙的全球恒星形成率密度，并且可能是蓝色恒星形成星系在宇宙时间内转变为红色静止星系的一个因素。我们研究了棱镜多天体巡天（PRIMUS）中孤立的紧密星系对中潮汐触发的恒星形成，PRIMUS是一个低色散棱镜红移巡天，测量了~ 120，000个到z ~ 1的红移超过9.1度^[2]的星系。我们选择了一个孤立星系对中的星系样本，这些星系的红移为0.25 < z < 0.75，在300 h^-1 kpc的投影距离内没有其他天体，dz/（1+z）= 0.01，并将它们与孤立星系的对照样本进行比较，以检验它们的静止坐标系FUV-r和NUV-r颜色的系统差异，作为相对特定SFR的替代。我们发现，r_p < 50 h^-1 kpc对的星系比对照星系平均具有更蓝的尘埃校正UV-r颜色，在FUV-r中为-0.134 +/- 0.045星等，在NUV-r中为-0.075 +/- 0.038星等，对应于SSFR增加约15-20%。这表明由于潮汐相互作用，SSFR增强。我们还发现，对于r_p < 30 h^-1 kpc的配对星系子集，这种相对增强更大，其平均色偏移在FUV-r中为-0.193 +/- 0.065星等，在NUV-r中为-0.159 +/- 0.048星等，对应于SSFR增加约25-30%。我们测试了在整个样本红移范围内潮汐触发恒星形成增强的演化，并发现了SSFR增强从0.25 < z < 0.5到0.5 < z < 0.75的边缘证据。这表明，在低密度环境中由潮汐相互作用引发的增强的恒星形成的变化并不是在这个红移范围内全球恒星形成率密度下降的原因。
英文摘要：
Tidal interactions between galaxies can trigger star formation, which contributes to the global star formation rate density of the universe and could be a factor in the transformation of blue, star-forming galaxies to red, quiescent galaxies over cosmic time. We investigate tidally-triggered star formation in isolated close galaxy pairs drawn from the Prism Multi-Object Survey (PRIMUS), a low-dispersion prism redshift survey that has measured ~120,000 robust galaxy redshifts over 9.1 deg^2 out to z ~ 1. We select a sample of galaxies in isolated galaxy pairs at redshifts 0.25 < z < 0.75, with no other objects within a projected separation of 300 h^-1 kpc and dz/(1+z) = 0.01, and compare them to a control sample of isolated galaxies to test for systematic differences in their rest-frame FUV-r and NUV-r colors as a proxy for relative specific SFR. We find that galaxies in r_p < 50 h^-1 kpc pairs have bluer dust-corrected UV-r colors on average than the control galaxies by -0.134 +/- 0.045 magnitudes in FUV-r and -0.075 +/- 0.038 magnitudes in NUV-r, corresponding to a ~15-20% increase in SSFR. This indicates an enhancement in SSFR due to tidal interactions. We also find that this relative enhancement is greater for a subset of r_p < 30 h^-1 kpc pair galaxies, for which the average colors offsets are -0.193 +/- 0.065 magnitudes in FUV-r and -0.159 +/- 0.048 magnitudes in NUV-r, corresponding to a ~25-30% increase in SSFR. We test for evolution in the enhancement of tidally-triggered star formation with redshift across our sample redshift range and find marginal evidence for a decrease in SSFR enhancement from 0.25 < z < 0.5 to 0.5 < z < 0.75. This indicates that a change in enhanced star formation triggered by tidal interactions in low density environments is not a contributor to the decline in the global star formation rate density across this redshift range.
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