Galaxy morphology to I = 25 mag in the Hubble Deep Field
Galaxy morphology to I = 25 mag in the Hubble Deep Field
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DOI：
10.1093/mnras/279.3.l47
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发表时间：
1996-02
影响因子：
4.8
通讯作者：
R. Abraham;Nial R. Tanvir;B. Santiago;R. S. Ellis;K. Glazebrook;S. Bergh
中科院分区：
文献类型：
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作者：
R. Abraham;Nial R. Tanvir;B. Santiago;R. S. Ellis;K. Glazebrook;S. Bergh
利用基于星系中心浓度和不对称性测量的定量分类系统，研究了哈勃深场中21<；i<；25mag范围内星系的形态特征。哈勃深场中天体的类别分布强烈地偏向高度不对称的天体，相对于1<；22 MAG的HST Medium Deep Survey和一个人为红移的局部星系样本的分布。Glazebrook等人在I<；22MAG上报道的不规则/特殊/合并系统的数量急剧增加的计数-量级关系。持续到至少1=25 MAG。虽然这些特殊的系统在光学波长上主要是蓝色的，但有相当一部分也显示出红色的U-B颜色，这可能表明它们处于高红移。在Glazebrook等人的S星等极限之外，螺旋计数似乎比高归一化非演化预测的上升幅度更大，而椭圆/SO星系的螺旋计数仅略高于此类预测，并可能超过I‘24 MAG。这些结果与以前用HST研究暗星系形态的结果进行了比较，并简要讨论了可能的影响。哈勃深场中的大部分特殊/不规则/合并系统表明，到I’25 MAG时，传统的哈勃系统不再能充分描述高比例场星系的形态特征。
The morphological properties of galaxies in the range 21 < I < 25 mag in the Hubble Deep Field are investigated using a quantitative classification system based on measurements of the central concentration and asymmetry of galaxian light. The class distribution of objects in the Hubble Deep Field is strongly skewed towards highly asymmetric objects, relative to distributions from both the HST Medium Deep Survey at 1< 22 mag and an artificially redshifted sample of local galaxies. The steeply rising number count-magnitude relation for irregular/peculiar/merging systems at I < 22 mag reported by Glazebrook et al. continues to at least 1=25 mag. Although these peculiar systems are predominantly blue at optical wavelengths, a significant fraction also exhibit red U - B colours, which may indicate that they are at high redshift. Beyond Glazebrook et al.'s magnitude limit, the spiral counts appear to rise more steeply than high-normalization no-evolution predictions, whereas those of elliptical/SO galaxies only slightly exceed such predictions and may turn over beyond I '" 24 mag. These results are compared with those from previous investigations of faint galaxy morphology with HST, and the possible implications are briefly discussed. The large fraction of peculiar/irregular/merging systems in the Hubble Deep Field suggests that by I '" 25 mag the conventional Hubble system no longer provides an adequate description of the morphological characteristics of a high fraction of field galaxies.