High frequency peakers. I. The bright sample.pdf

High frequency peakers. I. The bright sample.pdf

  1. 1、本文档共19页,可阅读全部内容。
  2. 2、原创力文档(book118)网站文档一经付费(服务费),不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
  3. 3、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。如您付费,意味着您自己接受本站规则且自行承担风险,本站不退款、不进行额外附加服务;查看《如何避免下载的几个坑》。如果您已付费下载过本站文档,您可以点击 这里二次下载
  4. 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“版权申诉”(推荐),也可以打举报电话:400-050-0827(电话支持时间:9:00-18:30)。
查看更多
High frequency peakers. I. The bright sample

a r X i v : a s t r o - p h / 0 0 1 2 4 2 8 v 1 2 0 D e c 2 0 0 0 AA manuscript no. (will be inserted by hand later) Your thesaurus codes are: 03 11.01.2 13.18.1 11.17.3 ASTRONOMY AND ASTROPHYSICS High Frequency Peakers: I. The Bright Sample D. Dallacasa1,2, C. Stanghellini3, M. Centonza1,2, and R. Fanti4,2 1 Dipartimento di Astronomia, Via Ranzani 1, I-40127 Bologna, Italy 2 Istituto di Radioastronomia - CNR, Via Gobetti 101, I-40129 Bologna, Italy. 3 Istituto di Radioastronomia - C. P. 169, I-96017 Noto (SR), Italy 4 Dipartimento di Fisica, Via Irnerio n. 46, I-40126 Bologna, Italy. Received 11 July 2000; accepted 9 October 2000 Abstract. Here we present a sample of sources with con- vex radio spectra peaking at frequencies above a few GHz. We call these radio sources High Frequency Peakers (HFPs). This sample extends to higher turnover frequen- cies than the samples of Compact Steep Spectrum (CSS) and GHz Peaked Spectrum (GPS) radio sources. HFPs are rare due to the strong bias against them caused by their turnover occurring at frequencies about one order of magnitude higher than in CSS-GPS samples. The sample has been selected by a comparison between the Green Bank survey (87GB) at 4.9 GHz and the NRAO VLA Sky Survey (NVSS) at 1.4 GHz. Then the candidates have been observed with the VLA at 1.365, 1.665, 4.535, 4.985, 8.085, 8.485, 14.96 and 22.46 GHz in order to de- rive a simultaneous radio spectrum, and remove variable sources from the sample. The final list of genuine HFP sources consists of 55 objects with flux density exceeding 300 mJy at 4.9 GHz at the time of the 87GB observa- tion. Optical identifications are available for 29 of them; 24 are high redshift quasars, 3 are galaxies (one of them has indeed broad lines in the optical spectrum) and 2 are BL Lac objects. The remaining sources are mostly empty fields (17) on the digitised POSS or have uncertain classi- fication (9). Key words: Galaxies: active – Radio Continuum: Galax- ies – Quasars: Genera

文档评论(0)

l215322 + 关注
实名认证
内容提供者

该用户很懒,什么也没介绍

1亿VIP精品文档

相关文档