The VLBA CANDELS GOODS-North Survey. I - Survey Design, Processing, Data Products, and Source Counts
The VLBA CANDELS GOODS-North Survey. I - Survey Design, Processing, Data Products, and Source Counts
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VLBA CANDELS GOODS-North 调查。
DOI：
10.1093/mnras/stae253
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发表时间：
2024
影响因子：
4.8
通讯作者：
Deane R
中科院分区：
文献类型：
--
作者：
Deane R
在过去十年中，广域厘米波甚长基线干涉测量技术(VLBI)取得了重大进展，考虑到电磁频谱上主要设施的广域天气调查驱动战略，这一技术是及时的。虽然宽视场VLBI带来了重大的后处理挑战，可能会严重限制其潜在的科学产量，但千米级连接元件干涉仪球体的许多发展直接适用于解决这些问题。在这里，我们介绍了CANDELS Goods-North油田的深(11μJy BEAM−1)、准均匀灵敏度、连续宽视场(160arcmin2)1.6GHz VLBI测量的设计、处理、数据产品和震源计数。这是研究得最好的河外场之一，分辨率为毫角秒，因此非常适合作为我们的Tera像素VLBI图像的比较研究。导出的VLBI源计数与在COSMOS场中测量的源计数一致，COSMOS场大致追踪在Arc第二尺度射电调查中探测到的活动星系核人口。然而，在S1.4 GHz∼100-500μJy通量密度范围内有一个明显的平坦化，这表明紧凑微弱射电源的数量发生了转变，与15 GHz的过剩源计数定性一致，这被认为是未建模的射电核心数量。这一调查方法将有助于得出可靠的甚大比例源计数，并为今后的广场甚小比测扩大发现空间，包括采用平方公里阵列的甚大比例尺，其中将包括非洲大陆≳1000公里基线上的新的大视场天线。此外，它在设计监测和/或快速触发的VLBI瞬变程序时可能很有用。
The past decade has seen significant advances in wide-field cm-wave very long baseline interferometry (VLBI), which is timely given the wide-area, synoptic survey-driven strategy of major facilities across the electromagnetic spectrum. While wide-field VLBI poses significant post-processing challenges that can severely curtail its potential scientific yield, many developments in the km-scale connected-element interferometer sphere are directly applicable to addressing these. Here we present the design, processing, data products, and source counts from a deep (11μJy beam−1), quasi-uniform sensitivity, contiguous wide-field (160 arcmin2) 1.6 GHz VLBI survey of the CANDELS GOODS-North field. This is one of the best-studied extragalactic fields at milli-arcsecond resolution and, therefore, is well-suited as a comparative study for our Tera-pixel VLBI image. The derived VLBI source counts show consistency with those measured in the COSMOS field, which broadly traces the AGN population detected in arcsecond-scale radio surveys. However, there is a distinctive flattening in theS1.4GHz∼100–500μJy flux density range, which suggests a transition in the population of compact faint radio sources, qualitatively consistent with the excess source counts at 15 GHz that is argued to be an unmodelled population of radio cores. This survey approach will assist in deriving robust VLBI source counts and broadening the discovery space for future wide-field VLBI surveys, including VLBI with the Square Kilometre Array, which will include new large field-of-view antennas on the African continent at ≳1000 km baselines. In addition, it may be useful in the design of both monitoring and/or rapidly triggered VLBI transient programmes.