A wide-area GMRT 610-MHz survey of ELAIS N1 field
A wide-area GMRT 610-MHz survey of ELAIS N1 field
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ELAIS N1 领域的广域 GMRT 610 MHz 勘测
DOI：
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发表时间：
2020
期刊：
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通讯作者：
E. Ocran
中科院分区：
文献类型：
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作者：
C. Ishwara;C. Ishwara;A. Taylor;A. Taylor;D. Green;J. Stil;Mattia Vaccari;Mattia Vaccari;E. Ocran
在本文中，我们提出了一个广域610兆赫调查的ELAIS，N1场与GMRT，覆盖面积为12.8 deg$^2$，分辨率为6 arcsec和均方根噪声为$sim 40$mu$Jy波束$^{-1}$。这相当于频谱指数为$-0.75$时1.4 GHz处的$sim 20$ $mu$Jy波束$^{-1}$ rms噪声。调查的主要目标是研究在$<$ GHz频率下的亚毫焦耳通量密度下的极化天空。此外，一系列其他科学目标，如调查的性质，低频$mu$Jy源人口和无线电喷流的排列。在这一地区共发现了6,400个放射源，其中绝大多数是致密的。由GMRT在610 MHz和VLA FIRST在1.4GHz联合检测的样品具有的中值光谱指数为-0.85 pm 0.05$，中值610 MHz通量密度为4.5 mJ y。该区域具有丰富的辅助数据，可用于表征检测到的源。多波长交叉匹配导致光学/红外对应物的无线电源的90%，与一个显着的分数至少有光度红移。由于这次调查的灵敏度比以前的调查有所提高，我们已经发现了六个巨大的射电源（GRS），其中三个在z sim 1$或更高。这意味着GRS的人口可能比迄今为止已知的更丰富和更常见，如果这是真的，这对光度函数和射电源的演变有影响。我们还确定了几个候选的扩展遗迹来源。
In this paper we present a wide-area 610 MHz survey of the ELAIS,N1 field with the GMRT, covering an area of 12.8 deg$^2$ at a resolution of 6 arcsec and with an rms noise of $sim 40$ $mu$Jy beam$^{-1}$. This is equivalent to $sim 20$ $mu$Jy beam$^{-1}$ rms noise at 1.4 GHz for a spectral index of $-0.75$. The primary goal of the survey was to study the polarised sky at sub-mJy flux densities at $<$ GHz frequencies. In addition, a range of other science goals, such as investigations in to the nature of the low-frequency $mu$Jy source populations and alignments of radio jets. A total of 6,400 sources were found in this region, the vast majority of them compact. The sample jointly detected by GMRT at 610 MHz and by VLA FIRST at 1.4,GHz has a median spectral index of $-0.85 pm 0.05$ and a median 610 MHz flux density of 4.5 mJy. This region has a wealth of ancillary data which is useful to characterize the detected sources. The multi-wavelength cross matching resulted optical/IR counterparts to $sim 90$ per~cent of the radio sources, with a significant fraction having at least photometric redshift. Due to the improved sensitivity of this survey over preceding ones, we have discovered six giant radio sources (GRS), with three of them at $z sim 1$ or higher. This implies that the population of GRS may be more abundant and common than known to date and if true this has implications for the luminosity function and the evolution of radio sources. We have also identified several candidate extended relic sources.