Ultraviolet Galaxy Counts from Space Telescope Imaging Spectrograph Observations of the Hubble Deep Fields
Ultraviolet Galaxy Counts from Space Telescope Imaging Spectrograph Observations of the Hubble Deep Fields
复制标题
哈勃深场太空望远镜成像摄谱仪观测中的紫外线星系计数
DOI：
10.1086/312930
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
H. Ferguson
中科院分区：
文献类型：
--
作者：
J. Gardner;T. Brown;H. Ferguson
我们给出了近紫外（NUV; 2365 Å）和远紫外（FUV; 1595 Å）的星系计数，这些星系计数来自太空望远镜成像光谱仪对哈勃深场北（HDF-N）、哈勃深场南（HDF-S）和HDF-N附近平行场的部分观测。所有三个场都有深（AB bbbb29）光学成像，我们通过在限制光学同质团内检测到的紫外线通量来确定星等。对检测到的物体的紫外光学颜色进行分析，结合对紫外图像的目视检查，表明在紫外图像中没有在光学中检测不到的可检测物体。我们根据HDF-N宽视场行星相机2 (WFPC2) V + I图像模拟的星系分布来确定我们的探测区域和完整性。星系计数达到NUVAB = 29和FUVAB = 30，比HDF-N WFPC2/F300W计数暗1等，比气球计数暗7等。我们整合了我们的测量结果，以呈现来自已分解物体的河外背景辐射。NUV星系计数显示，在NUVAB = 26.0左右开始出现变平或翻转，这既不是基于具有陡峭微弱斜率的局部光度函数的无演化模型所预测的，也不是由主要合并引起的星暴的半解析模型所预测的。FUV计数也显示出一个平缓的斜率。我们认为，平坦的斜坡可能是由恒星形成的短工作周期、小合并引发的额外星暴以及星暴发作之间延长的静止阶段造成的。
We present galaxy counts in the near-ultraviolet (NUV; 2365 Å) and far-ultraviolet (FUV; 1595 Å) obtained from Space Telescope Imaging Spectrograph observations of portions of the Hubble Deep Field-North (HDF-N), the Hubble Deep Field-South (HDF-S), and a parallel field near the HDF-N. All three fields have deep (AB > 29) optical imaging, and we determine magnitudes by taking the ultraviolet flux detected within the limiting optical isophote. An analysis of the UV-optical colors of detected objects, combined with a visual inspection of the UV images, indicates that there are no detectable objects in the UV images that are not also detected in the optical. We determine our detection area and completeness as a function of magnitude with a simulated distribution of galaxies based on the HDF-N Wide Field Planetary Camera 2 (WFPC2) V + I image. The galaxy counts reach to NUVAB = 29 and FUVAB = 30, which is 1 mag fainter than the HDF-N WFPC2/F300W counts and 7 mag fainter than balloon-based counts. We integrate our measurements in order to present the extragalactic background radiation coming from resolved objects. The NUV galaxy counts show a flattening or turnover beginning at about NUVAB = 26.0, which is not predicted either by no-evolution models based on a local luminosity function with a steep faint-end slope or by a semianalytic model in which starbursts are caused by major mergers. The FUV counts also show a flat slope. We argue that the flat slopes could be caused by a short duty cycle for star formation, additional starbursts triggered by minor mergers, and an extended quiescent phase between starburst episodes.