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arXiv 2102.02241astro-ph.GA
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斯巴鲁HSC中大质量中央星系低表面亮度外围的性质和起源

The nature and origins of the low surface brightness outskirts of massive, central galaxies in Subaru HSC

Thomas M. Jackson, Anna Pasquali, Francesco La Barbera, Surhud More, Eva K. Grebel

摘要:

我们探索118个低红移、大质量的中央星系的恒星质量密度和颜色分布,这些星系在6 Gyr前聚集了90%的恒星质量,找到了小合并活动的证据,这些活动预计是静止星系尺寸增长背后的驱动力。我们使用成像数据的$g, r, i, z, y$波段的斯巴鲁超级Suprime-Cam调查和执行SED拟合构建空间分辨的径向配置文件的颜色和恒星质量的表面密度。我们的视觉形态分类显示,我们的样品的$\sim 42$百分比显示潮汐特征,类似于以前的研究,其余样品的$\sim 43$百分比显示弥漫的恒星晕,只有$\sim 14$百分比显示没有功能,下降到一个有限的$μ_{r\mathrm{-band}}$ $\sim$ 28 mag arcsec $^{-2}$。我们发现我们的样品堆叠的颜色配置文件之间的协议,从以前的研究和预期的平滑,下降的恒星质量表面密度分布在中心区域(< 3 R $_{\mathrm{e}}$)。然而,我们也看到了一个扁平的轮廓($Σ_* \sim 10^{7.5}$ M $_\odot$千秒差距$^{-2}$)在郊区(高达10 R $_{\mathrm{e}}$),这是我们的方法,专门针对潮汐/吸积功能。我们发现类似水平的潮汐特征和行为的恒星质量表面密度分布在一个年轻的比较样本,但缺乏扩散晕。我们还应用叠加技术,类似于以前的研究,发现这样的程序冲洗潮汐功能,从而产生平滑下降的配置文件。外围的恒星物质平均贡献了$\sim 10^{10}$ M $_\odot$或恒星总质量的百分之几,并与类似恒星质量的SDSS卫星具有相似的颜色。

英文摘要:

We explore the stellar mass density and colour profiles of 118 low redshift, massive, central galaxies, selected to have assembled 90 percent of their stellar mass 6 Gyr ago, finding evidence of the minor merger activity expected to be the driver behind the size growth of quiescent galaxies. We use imaging data in the $g, r, i, z, y$ bands from the Subaru Hyper Suprime-Cam survey and perform SED fitting to construct spatially well-resolved radial profiles in colour and stellar mass surface density. Our visual morphological classification reveals that $\sim 42$ percent of our sample displays tidal features, similar to previous studies, $\sim 43$ percent of the remaining sample display a diffuse stellar halo and only $\sim 14$ percent display no features, down to a limiting $μ_{r\mathrm{-band}}$ $\sim$ 28 mag arcsec$^{-2}$. We find good agreement between the stacked colour profiles of our sample to those derived from previous studies and an expected smooth, declining stellar mass surface density profile in the central regions (< 3 R$_{\mathrm{e}}$). However, we also see a flattening of the profile ($Σ_* \sim 10^{7.5}$ M$_\odot$ kpc$^{-2}$) in the outskirts (up to 10 R$_{\mathrm{e}}$), which is revealed by our method of specifically targeting tidal/accretion features. We find similar levels of tidal features and behaviour in the stellar mass surface density profiles in a younger comparison sample, however a lack of diffuse haloes. We also apply stacking techniques, similar to those in previous studies, finding such procedures wash out tidal features and thereby produces smooth declining profiles. The stellar material in the outskirts contributes on average $\sim 10^{10}$ M$_\odot$ or a few percent of the total stellar mass and has similar colours to SDSS satellites of similar stellar mass.

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