On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedback
On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedback
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DOI：
10.1093/mnras/sty1651
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发表时间：
2018-06
影响因子：
4.8
通讯作者：
J. Bermejo-Climent;G. Battaglia;C. Gallart;A. Di Cintio-A.-Di Cintio-2125284323;C. Brook;L. Cicuéndez;M. Monelli;R. Leaman;L. Mayer;J. Peñarrubia;J. Read
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作者：
J. Bermejo-Climent;G. Battaglia;C. Gallart;A. Di Cintio-A.-Di Cintio-2125284323;C. Brook;L. Cicuéndez;M. Monelli;R. Leaman;L. Mayer;J. Peñarrubia;J. Read
根据星星形成历史（SFH），本星系群矮星系可以大致分为两类：一类是在z = 2之前形成大部分恒星的星系（快），另一类是具有更长SFH的星系（慢）。最精确的SFH通常来自深但空间扩展不太大的光度数据;当存在年龄梯度时，这可能会改变年老恒星与年轻恒星的比例。在这里，我们纠正这种影响，并推导出质量的恒星z = 2的样本16个本群矮星系。我们探讨了快矮星和慢矮星之间的早期差异，并评估了超新星（SNe）对矮星的重子和暗物质（DM）成分的内部反馈的影响。快矮星在早期聚集了更多的恒星质量，并且在半光半径内比慢矮星有更多的DM。通过实施，慢矮星不能失去他们的气体z = 2，我们限制SN反馈的气体和DM的最大耦合效率为10%.We发现，内部反馈似乎不足以淬灭SFH的快速矮星的气体剥夺，特别是对于较暗的系统。尽管如此，SN反馈可以相对容易地使DM晕密度分布成核，以非常低的效率在z = 2的快矮星中产生半光半径大小的核。在“经典”的银河系卫星中，我们预测最小的核心应该在天龙座和小熊座，而雕塑家和天炉座应该拥有最大的核心。
According to star formation histories (SFHs), Local Group dwarf galaxies can be broadly classified in two types: those forming most of their stars before z = 2 (fast) and those with more extended SFHs (slow). The most precise SFHs are usually derived from deep but not very spatially extended photometric data; this might alter the ratio of old to young stars when age gradients are present. Here, we correct for this effect and derive the mass formed in stars by z = 2 for a sample of 16 Local Group dwarf galaxies. We explore early differences between fast and slow dwarfs, and evaluate the impact of internal feedback by supernovae (SNe) on the baryonic and dark matter (DM) component of the dwarfs. Fast dwarfs assembled more stellar mass at early times and have larger amounts of DM within the half-light radius than slow dwarfs. By imposing that slow dwarfs cannot have lost their gas by z = 2, we constrain the maximum coupling efficiency of SN feedback to the gas and to the DM to be 10 per cent. We find that internal feedback alone appears insufficient to quench the SFH of fast dwarfs by gas deprivation, in particular for the fainter systems. Nonetheless, SN feedback can core the DM halo density profiles relatively easily, producing cores of the sizes of the half-light radius in fast dwarfs by z = 2 with very low efficiencies. Amongst the `classical' Milky Way satellites, we predict that the smallest cores should be found in Draco and Ursa Minor, while Sculptor and Fornax should host the largest ones.