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arXiv 1701.03471astro-ph.GAastro-ph.CO
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z ~ 0.6以来致密静止星系的丰度

The abundance of compact quiescent galaxies since z ~ 0.6

Aldée Charbonnier, Marc Huertas-Company, Thiago S. Gonçalves, Karín Menéndez-Delmestre, Kevin Bundy, Emmanuel Galliano, Bruno Moraes, Martín Makler, Maria E. S.… 展开作者

Aldée Charbonnier, Marc Huertas-Company, Thiago S. Gonçalves, Karín Menéndez-Delmestre, Kevin Bundy, Emmanuel Galliano, Bruno Moraes, Martín Makler, Maria E. S. Pereira, Thomas Erben, Hendrik Hildebrandt, Huan-Yuan Shan, Gabriel B. Caminha, Marco Grossi, Laurie Riguccini

摘要:

我们开始量化中等红移的静止大质量致密星系的数密度。我们使用CFHT赤道SDSS Stripe 82(CS 82)调查(约170平方英尺)基于i波段成像确定结构参数。度),利用约0.6“的精细中值视野。我们选择了红移范围为0.2&lt;z 10的致密大质量(M &gt; 5 × 10^10 M_sun)星系<0.6. The large volume sampled allows to decrease the effect of cosmic variance that has hampered the calculation of the number density for this enigmatic population in many previous studies. We undertake an exhaustive analysis in an effort to untangle the various findings inherent to the diverse definition of compactness present in the literature. We find that the absolute number of compact galaxies is very dependent on the adopted definition and can change up to a factor of >。我们系统地测量了在相同的红移比以前报道的更小的领域与HST成像,这是更多的宇宙方差的影响的一个因素~5更多的紧凑。这意味着数密度从z ~ 1.5到z ~ 0.2的降低可能仅为约2-5倍,显著小于先前报道的。这支持祖细胞偏倚作为大小演变的主要贡献者。这种温和的下降与最近数值模拟的预测大致相符。只有最极端的致密星系,即Reff &lt;1.5 x(M/10^11 M_sun)^0.75和M &gt; 10^10.7 M_sun的星系,其数量似乎减少了约20倍,因此可能经历了明显的大小演化。

英文摘要:

We set out to quantify the number density of quiescent massive compact galaxies at intermediate redshifts. We determine structural parameters based on i-band imaging using the CFHT equatorial SDSS Stripe 82 (CS82) survey (~170 sq. degrees) taking advantage of an exquisite median seeing of ~0.6''. We select compact massive (M > 5x10^10 M_sun) galaxies within the redshift range of 0.2<z<0.6. The large volume sampled allows to decrease the effect of cosmic variance that has hampered the calculation of the number density for this enigmatic population in many previous studies. We undertake an exhaustive analysis in an effort to untangle the various findings inherent to the diverse definition of compactness present in the literature. We find that the absolute number of compact galaxies is very dependent on the adopted definition and can change up to a factor of >10. We systematically measure a factor of ~5 more compacts at the same redshift than what was previously reported on smaller fields with HST imaging, which are more affected by cosmic variance. This means that the decrease in number density from z ~ 1.5 to z ~ 0.2 might be only of a factor of ~2-5, significantly smaller than what previously reported. This supports progenitor bias as the main contributor to the size evolution. This milder decrease is roughly compatible with the predictions from recent numerical simulations. Only the most extreme compact galaxies, with Reff < 1.5x( M/10^11 M_sun)^0.75 and M > 10^10.7 M_sun, appear to drop in number by a factor of ~20 and hence likely experience a noticeable size evolution.

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