The mass–metallicity relation of tidal dwarf galaxies

The mass–metallicity relation of tidal dwarf galaxies
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潮汐矮星系的质量-金属丰度关系

DOI：
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发表时间：
2015
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通讯作者：
S. Ploeckinger
S. Ploeckinger
中科院分区：
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文献类型：
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作者：
S. Recchi;P. Kroupa;S. Ploeckinger;S. Ploeckinger

文献摘要

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矮星系通常遵循质量-金属丰度（MZ）关系，质量越大的天体保留的重元素比例越大。年轻的潮汐矮星系（TDGs），诞生于富气体星系相互作用产生的潮汐尾，被认为不遵循MZ关系，因为它们继承了更大质量的母星系的金属丰度。我们提出的化学演化模型，以调查如果TDGs，形成在非常高的红移，那里的母星系的金属丰度是非常低的，可以产生所观察到的MZ关系。假设在密度较高的高红移宇宙中，星系间的相互作用更为频繁，TDG可能对矮星系的数量有重要贡献。通过对TDG化学演化模型的研究，首次获得了依赖于星星形成速率和气体金属丰度的恒星初始质量函数（IMF），并应用星系积分IMF（IGIMF）理论对TDG的演化过程进行了描述。由于TDGs形成的相互作用星系的潮汐碎片，预富集的气体，一个潜在的预先存在的恒星人口，下降，和质量依赖的外流被认为是。年轻的TDG的模型，创建在强预富集潮汐臂与预先存在的恒星人口可以解释观测到的TDG的丰度比测量。TDG的相同化学演化模型，形成了最初金属丰度非常低的气体，自然建立了观察到的MZ关系。因此，模拟的古代TDGs的化学成分与观测到的卫星星系的MZ关系是一致的。
Dwarf galaxies generally follow a mass-metallicity (MZ) relation, where more massive objects retain a larger fraction of heavy elements. Young tidal dwarf galaxies (TDGs), born in the tidal tails produced by interacting gas-rich galaxies, have been thought to not follow the MZ relation, because they inherit the metallicity of the more massive parent galaxies. We present chemical evolution models to investigate if TDGs that formed at very high redshifts, where the metallicity of their parent galaxy was very low, can produce the observed MZ relation. Assuming that galaxy interactions were more frequent in the denser high-redshift universe, TDGs could constitute an important contribution to the dwarf galaxy population. The survey of chemical evolution models of TDGs presented here captures for the first time an initial mass function (IMF) of stars that is dependent on both the star formation rate and the gas metallicity via the integrated galactic IMF (IGIMF) theory. As TDGs form in the tidal debris of interacting galaxies, the pre-enrichment of the gas, an underlying pre-existing stellar population, infall, and mass dependent outflows are considered. The models of young TDGs that are created in strongly pre-enriched tidal arms with a pre-existing stellar population can explain the measured abundance ratios of observed TDGs. The same chemical evolution models for TDGs, that form out of gas with initially very low metallicity, naturally build up the observed MZ relation. The modelled chemical composition of ancient TDGs is therefore consistent with the observed MZ relation of satellite galaxies.