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arXiv 2107.05030astro-ph.GA
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SDSS-IV MaNGA星系中心恒星星族的研究:具有异常年轻和大质量恒星的子样本的识别

A study of the central stellar populations of galaxies in SDSS-IV MaNGA: identification of a sub-sample with unusually young and massive stars

Guinevere Kauffmann

摘要:

本文描述了一个搜索的星系中心,明确的迹象不寻常的恒星星族的初始质量函数平坦比Salpeter在高恒星质量。在668个恒星质量在10^10- 10^11 M_sol范围内的正面星系样本中,我确定了15个具有年轻到中等年龄中心恒星星族的星系,这些星系的内部区域具有不寻常的恒星星族梯度。在这些星系中,4000埃的破裂要么是平坦的,要么向星系中心上升,这表明中心区域拥有演化的恒星,但H $α$等效宽度在中心区域也急剧上升。这些星系中心的电离参数[OIII]/[OII]通常很低,表明电离源是恒星而不是活动星系核。沃尔夫-拉叶特特征是年轻热恒星的特征,经常在光谱中发现,并且这些特征在较小的银河系中心半径处也逐渐变强。这些异常值进行比较,以控制样本的星系类似的质量与年轻的内部恒星星族,但在Halpha的梯度等效宽度和4000埃的突破遵循彼此更密切。异常值更频繁地表现出中心沃尔夫-拉叶红凸过度,它们具有更高的中心恒星和电离气体金属丰度,并且它们也更频繁地在20厘米无线电波长处被检测到。我强调一个离群点,那里的电离气体显然受到强烈的扰动,要么被大质量恒星爆炸成超新星,要么被物质落入黑洞的能量注入。

英文摘要:

This paper describes a search for galaxy centers with clear indications of unusual stellar populations with an initial mass function flatter than Salpeter at high stellar masses. Out of a sample of 668 face-on galaxies with stellar masses in the range 10^10- 10^11 M_sol, I identify 15 galaxies with young to intermediate age central stellar populations with unusual stellar population gradients in the inner regions of the galaxy. In these galaxies, the 4000 Angstrom break is either flat or rising towards the center of the galaxy, indicating that the central regions host evolved stars, but the H$α$ equivalent width also rises steeply in the central regions. The ionization parameter [OIII]/[OII] is typically low in these galactic centers, indicating that ionizing sources are stellar rather than AGN. Wolf Rayet features characteristic of hot young stars are often found in the spectra and these also get progressively stronger at smaller galactocentric radii. These outliers are compared to a control sample of galaxies of similar mass with young inner stellar populations, but where the gradients in Halpha equivalent width and 4000 Angstrom break follow each other more closely. The outliers exhibit central Wolf Rayet red bump excesses much more frequently, they have higher central stellar and ionized gas metallicities, and they are also more frequently detected at 20 cm radio wavelengths. I highlight one outlier where the ionized gas is clearly being strongly perturbed and blown out either by massive stars after they explode as supernovae, or by energy injection from matter falling onto a black hole.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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