发表机构
Faculty of Engineering, Hokkai-Gakuen University（北海道学园大学工学部）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究红移z~2大质量尘埃形成恒星星系的核球形成，结合JWST、NIRCam及ALMA数据，通过多波段成像和SED拟合等方法，发现多数星系核球已形成并将演化，部分仍处于核球形成压缩阶段，捕捉到核球形成多阶段情况。
AI 中文摘要
我们通过结合詹姆斯·韦布空间望远镜（JWST）中红外成像仪（MIRI）F770W图像、近红外相机（NIRCam）的八个波段图像以及阿塔卡马大型毫米/亚毫米波阵列（ALMA）870微米数据，研究了16个红移z~2的大质量尘埃形成恒星星系中的核球形成。在红移中值z = 2.18时，F770W波段探测静止帧2.4微米光，接近静止帧K波段，且追踪恒星质量分布时受尘埃消光影响小。F770W测量的有效半径与870微米尘埃发射的相符，中值比为0.95，通常比F444W中的小23%。因此，静止帧K波段成像对于测量恒星质量的真实范围至关重要。在16个星系的堆叠图像中，870微米和F770W轮廓在8千秒差距内紧密一致，F770W堆叠的核球加盘分解给出核球与总光度比为0.50。用CIGALE对径向区间的SED进行拟合，发现消光从中心的Av = 2.6星等降至r≥7千秒差距处的1.5星等，而特定恒星形成率轮廓是平坦的。在这些星系中，核球已形成，整个系统在约10亿年内向紧凑的宁静星系演化。相比之下，在两个星系中，870微米发射比F770W光紧凑3至6倍，这表明它们仍处于核球形成的压缩阶段。我们的样本可能捕捉到了大质量星系核球形成的几个阶段。
英文摘要
We study bulge formation in 16 massive dusty star-forming galaxies at z~2 by combining JWST MIRI F770W imaging, NIRCam imaging in eight bands, and ALMA 870 micron data. At the median redshift of z=2.18, the F770W band probes the rest-frame 2.4 micron light, close to the rest-frame K band, and traces the stellar mass distribution with much less dust attenuation than the NIRCam bands. The effective radii measured in F770W agree with those of the 870 micron dust emission, with a median ratio of 0.95, and are typically 23% smaller than those in F444W. The rest-frame K-band imaging is therefore essential to measure the true extent of the stellar mass, which is as compact as the dusty star-forming regions. In stacks of the 16 galaxies at a matched resolution, the 870 micron and F770W profiles agree closely out to 8 kpc, and a bulge plus disk decomposition of the F770W stack gives a bulge-to-total ratio of 0.50. Fitting the SEDs in radial bins with CIGALE, we find that the attenuation decreases from A_V = 3.7 mag at the center to 1.9 mag at r >~ 7 kpc, while the specific star formation rate profile is flat. In most of the galaxies, the bulge is already in place inside the dusty core. In two galaxies, by contrast, the 870 micron emission is 3 to 6 times more compact than the F770W light, which suggests that they are still in the bulge-building compaction phase. Our sample may thus catch massive galaxies in several phases of bulge formation.
CommentsAccepted for publication in ApJ. See Figure 4 for the key result that the stacked F770W and ALMA 870 micron profiles agree closely out to 8 kpc
